ALL-HAZARDS MITIGATION PLAN HAZARD IDENTIFICATION Identification.pdf · ALL-HAZARDS MITIGATION PLAN HAZARD IDENTIFICATION The objectives of the Hazard Identification section are two-fold:

ALL-HAZARDS MITIGATION PLAN

HAZARD IDENTIFICATION

The objectives of the Hazard Identification section are two-fold:

1) Identify hazards that may affect the University of South Carolina

(USC) regional campuses, and

2) Provide a general description of these hazards including the

background and state-wide notable occurrences.

Since the USC regional campuses cover most of the state, a general description of state risk and

facts are found in this section. (The following section, Section 5: Hazard Analysis, describes specific

details on location, spatial extent, historical occurrences, and probably of future occurrence for

each campus.) All of the information presented herein is based on existing federal, state and local

sources as referenced throughout.

HAZARD SELECTION

South Carolina is vulnerable to a wide range of natural and human-caused hazards that threaten

life and property. Current FEMA regulations and interim guidance under the Disaster Mitigation Act

of 2000 (DMA 2000) require, at a minimum, an evaluation of a full range of natural hazards. This

plan draws on hazards found in the South Carolina State Hazard Mitigation Plan and those

suggested under FEMA planning guidance in order to identify a full range of hazards. These hazards

were then reviewed by the USC Committee to determine which were relevant to the USC

campuses.

University of South Carolina Floodplain Management and Hazard Mitigation Planning Committee

(FMHMPC) reviewed and identified a number of hazards that are to be addressed in the USC

Hazard Mitigation Plan. All of the hazards included underwent an extensive process that utilized

input from USC Committee members, research of past disaster declarations for in South Carolina,

historical hazard occurrences, and a review of the current South Carolina State Hazard Mitigation

Plan. USC opted to focus on natural hazards in this plan as man-made hazards are identified and

planned for in separate planning documents. Readily available online information from reputable

sources such as federal and state agencies was also evaluated to supplement information from

these key sources.

Table 4.1 lists the full range of natural hazards initially identified for inclusion in the plan and

provides a brief description for each. This table includes 24 individual hazards. Some of these

hazards are considered to be interrelated or cascading, but for preliminary hazard identification

purposes these individual hazards are broken out separately.

Next, Table 4.2 documents the evaluation process used for determining which of the initially

identified hazards are considered significant enough for further evaluation in the risk assessment.

Code of Federal Regulations (CFR) Requirement

44 CFR Part 201.6(c)(2)(i): The risk assessment shall include a description of the type, location and extent of all natural

hazards that can affect the jurisdiction. The plan shall include information on previous occurrences of hazard events and on

the probability of future hazard events.


University of South Carolina Disaster Resistant University Plan

4:2

For each hazard considered, the table indicates whether or not the hazard was identified as a

significant hazard to be further assessed, how this determination was made, and why this

determination was made. The table works to summarize not only those hazards that were

identified (and why) but also those that were not identified (and why not). Hazard events not

identified for inclusion at this time may be addressed during future evaluations and updates of the

risk assessment if deemed necessary by the USC DRU Planning Team during the plan update

process.

Table 4.1: Descriptions of the Full Range of Initially Identified Hazards

Hazard Description

ATMOSPHERIC HAZARDS

Avalanche A rapid fall or slide of a large mass of snow down a mountainside.

Drought A prolonged period of less than normal precipitation such that the lack

of water causes a serious hydrologic imbalance. Common effects of

drought include crop failure, water supply shortages, and fish and

wildlife mortality. High temperatures, high winds, and low humidity

can worsen drought conditions and also make areas more susceptible

to wildfire. Human demands and actions have the ability to hasten or

mitigate drought-related impacts on local communities.

Hailstorm Any storm that produces hailstones that fall to the ground; usually

used when the amount or size of the hail is considered significant.

Hail is formed when updrafts in thunderstorms carry raindrops into

parts of the atmosphere where the temperatures are below freezing.

Heat Wave A heat wave may occur when temperatures hover 10 degrees or more

above the average high temperature for the region and last for

several weeks. Humid or muggy conditions, which add to the

discomfort of high temperatures, occur when a “dome” of high

atmospheric pressure traps hazy, damp air near the ground.

Excessively dry and hot conditions can provoke dust storms and low

visibility. A heat wave combined with a drought can be very

dangerous and have severe economic consequences on a community.

Hurricane and

Tropical Storm

Hurricanes and tropical storms are classified as cyclones and defined

as any closed circulation developing around a low-pressure center in

which the winds rotate counter-clockwise in the Northern Hemisphere

(or clockwise in the Southern Hemisphere) and with a diameter

averaging 10 to 30 miles across. When maximum sustained winds

reach or exceed 39 miles per hour, the system is designated a tropical

storm, given a name, and is closely monitored by the National

Hurricane Center. When sustained winds reach or exceed 74 miles

per hour the storm is deemed a hurricane. The primary damaging

forces associated with these storms are high-level sustained winds,

heavy precipitation and tornadoes. Coastal areas are also vulnerable

to the additional forces of storm surge, wind-driven waves and tidal

flooding which can be more destructive than cyclone wind. The

majority of hurricanes and tropical storms form in the Atlantic Ocean,

Caribbean Sea and Gulf of Mexico during the official Atlantic hurricane

season, which extends from June through November.



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Lightning Lightning is a discharge of electrical energy resulting from the buildup

of positive and negative charges within a thunderstorm, creating a

“bolt” when the buildup of charges becomes strong enough. This

flash of light usually occurs within the clouds or between the clouds

and the ground. A bolt of lightning can reach temperatures

approaching 50,000 degrees Fahrenheit. Lightning rapidly heats the

sky as it flashes, but the surrounding air cools following the bolt. This

rapid heating and cooling of the surrounding air causes thunder. On

average, 73 people are killed each year by lightning strikes in the

United States.

Tornado A tornado is a violently rotating column of air that has contact with

the ground and is often visible as a funnel cloud. Its vortex rotates

cyclonically with wind speeds ranging from as low as 40 mph to as

high as 300 mph. Tornadoes are most often generated by

thunderstorm activity when cool, dry air intersects and overrides a

layer of warm, moist air forcing the warm air to rise rapidly. The

destruction caused by tornadoes ranges from light to catastrophic

depending on the intensity, size and duration of the storm.

Severe Thunderstorm Thunderstorms are caused by air masses of varying temperatures

meeting in the atmosphere. Rapidly rising warm moist air fuels the

formation of thunderstorms. Thunderstorms may occur singularly, in

lines, or in clusters. They can move through an area very quickly or

linger for several hours. Thunderstorms may result in hail, tornadoes,

or straight-line winds. Windstorms pose a threat to lives, property,

and vital utilities primarily due to the effects of flying debris and can

down trees and power lines.

Winter Storm and

Freeze

Winter storms may include snow, sleet, freezing rain, or a mix of

these wintry forms of precipitation. Blizzards, the most dangerous of

all winter storms, combine low temperatures, heavy snowfall, and

winds of at least 35 miles per hour, reducing visibility to only a few

yards. Ice storms occur when moisture falls and freezes immediately

upon impact on trees, power lines, communication towers, structures,

roads and other hard surfaces. Winter storms and ice storms can

down trees, cause widespread power outages, damage property, and

cause fatalities and injuries to human life.

HYDROLOGIC HAZARDS

Dam and Levee

Failure

Dam failure is the collapse, breach, or other failure of a dam structure

resulting in downstream flooding. In the event of a dam failure, the

energy of the water stored behind even a small dam is capable of

causing loss of life and severe property damage if development exists

downstream of the dam. Dam failure can result from natural events,

human-induced events, or a combination of the two. The most

common cause of dam failure is prolonged rainfall that produces

flooding. Failures due to other natural events such as hurricanes,

earthquakes or landslides are significant because there is generally

little or no advance warning.

Erosion Erosion is the gradual breakdown and movement of land due to both

physical and chemical processes of water, wind, and general

meteorological conditions. Natural, or geologic, erosion has occurred

since the Earth’s formation and continues at a very slow and uniform

rate each year.



4:4

Flood The accumulation of water within a water body which results in the

overflow of excess water onto adjacent lands, usually floodplains.

The floodplain is the land adjoining the channel of a river, stream

ocean, lake or other watercourse or water body that is susceptible to

flooding. Most floods fall into the following three categories: riverine

flooding, coastal flooding, or shallow flooding (where shallow flooding

refers to sheet flow, ponding and urban drainage).

Storm Surge A storm surge is a large dome of water often 50 to 100 miles wide

and rising anywhere from four to five feet in a Category 1 hurricane

up to more than 30 feet in a Category 5 storm. Storm surge heights

and associated waves are also dependent upon the shape of the

offshore continental shelf (narrow or wide) and the depth of the ocean

bottom (bathymetry). A narrow shelf, or one that drops steeply from

the shoreline and subsequently produces deep water close to the

shoreline, tends to produce a lower surge but higher and more

powerful storm waves. Storm surge arrives ahead of a storm’s actual

landfall and the more intense the hurricane is, the sooner the surge

arrives. Storm surge can be devastating to coastal regions, causing

severe beach erosion and property damage along the immediate

coast. Further, water rise caused by storm surge can be very rapid,

posing a serious threat to those who have not yet evacuated flood-

prone areas.

GEOLOGIC HAZARDS

Earthquake A sudden, rapid shaking of the Earth caused by the breaking and

shifting of rock beneath the surface. This movement forces the

gradual building and accumulation of energy. Eventually, strain

becomes so great that the energy is abruptly released, causing the

shaking at the earth’s surface which we know as an earthquake.

Roughly 90 percent of all earthquakes occur at the boundaries where

plates meet, although it is possible for earthquakes to occur entirely

within plates. Earthquakes can affect hundreds of thousands of

square miles; cause damage to property measured in the tens of

billions of dollars; result in loss of life and injury to hundreds of

thousands of persons; and disrupt the social and economic

functioning of the affected area.

Expansive Soils Soils that will exhibit some degree of volume change with variations

in moisture conditions. The most important properties affecting

degree of volume change in a soil are clay mineralogy and the

aqueous environment. Expansive soils will exhibit expansion caused

by the intake of water and, conversely, will exhibit contraction when

moisture is removed by drying. Generally speaking, they often

appear sticky when wet, and are characterized by surface cracks

when dry. Expansive soils become a problem when structures are

built upon them without taking proper design precautions into account

with regard to soil type. Cracking in walls and floors can be minor, or

can be severe enough for the home to be structurally unsafe.

Landslide The movements of a mass of rock, debris, or earth down a slope

when the force of gravity pulling down the slope exceeds the strength

of the earth materials that comprise to hold it in place. Slopes

greater than 10 degrees are more likely to slide, as are slopes where

the height from the top of the slope to its toe is greater than 40 feet.



4:5

Slopes are also more likely to fail if vegetative cover is low and/or soil

water content is high.

Land

Subsidence/Sinkholes

The gradual settling or sudden sinking of the Earth’s surface due to

the subsurface movement of earth materials. Causes of land

subsidence include groundwater pumpage, aquifer system

compaction, drainage of organic soils, underground mining,

hydrocompaction, natural compaction, sinkholes, and thawing

permafrost.

Tsunami A series of waves generated by an undersea disturbance such as an

earthquake. The speed of a tsunami traveling away from its source

can range from up to 500 miles per hour in deep water to

approximately 20 to 30 miles per hour in shallower areas near

coastlines. Tsunamis differ from regular ocean waves in that their

currents travel from the water surface all the way down to the sea

floor. Wave amplitudes in deep water are typically less than one

meter; they are often barely detectable to the human eye. However,

as they approach shore, they slow in shallower water, basically

causing the waves from behind to effectively “pile up”, and wave

heights to increase dramatically. As opposed to typical waves which

crash at the shoreline, tsunamis bring with them a continuously

flowing ‘wall of water’ with the potential to cause devastating damage

in coastal areas located immediately along the shore.

Volcano A mountain that opens downward to a reservoir of molten rock below

the surface of the earth. While most mountains are created by forces

pushing up the earth from below, volcanoes are different in that they

are built up over time by an accumulation of their own eruptive

products: lava, ash flows, and airborne ash and dust. Volcanoes

erupt when pressure from gases and the molten rock beneath

becomes strong enough to cause an explosion.

OTHER HAZARDS

Hazardous Materials

Incident

Hazardous material (HAZMAT) incidents can apply to fixed facilities as

well as mobile, transportation-related accidents in the air, by rail, on

the nation’s highways and on the water. HAZMAT incidents consist of

solid, liquid and/or gaseous contaminants that are released from fixed

or mobile containers, whether by accident or by design as with an

intentional terrorist attack. A HAZMAT incident can last hours to days,

while some chemicals can be corrosive or otherwise damaging over

longer periods of time. In addition to the primary release, explosions

and/or fires can result from a release, and contaminants can be

extended beyond the initial area by persons, vehicles, water, wind

and possibly wildlife as well.

Public Heath

Emergencies

Events such as a pandemic that affect a large number of the

population.

Terror Threat Terrorism is defined by FEMA as, “the use of force or violence against

persons or property in violation of the criminal laws of the United

States for purposes of intimidation, coercion, or ransom.” Terrorist

acts may include assassinations, kidnappings, hijackings, bomb scares

and bombings, cyber-attacks (computer-based), and the use of

chemical, biological, nuclear and radiological weapons.



4:6

Sea Level Rise According to NOAA, sea level rise is defined as a mean rise is sea

level. As the ocean warms, sea water expands and continental ice

sheets melt, thus inundating areas with sea water that were

previously above sea level.

Wildfire An uncontrolled fire burning in an area of vegetative fuels such as

grasslands, brush, or woodlands. Heavier fuels with high continuity,

steep slopes, high temperatures, low humidity, low rainfall, and high

winds all work to increase risk for people and property located within

wildfire hazard areas or along the urban/wildland interface. Wildfires

are part of the natural management of forest ecosystems, but most

are caused by human factors. Over 80 percent of forest fires are

started by negligent human behavior such as smoking in wooded

areas or improperly extinguishing campfires. The second most

common cause for wildfire is lightning.



4:7

Table 4.2: Documentation of the Hazard Evaluation Process

Natural

Hazards

Considered

Was this

hazard

identified as

significant

enough to be

addressed in

the plan?

(Yes or No)

How was this

determination

made?

Why was this determination

made?

ATMOSPHERIC HAZARDS

Avalanche NO Review of US

Forest Service

National

Avalanche

Center web site

Review of the SC

State Hazard

Mitigation Plan

There is no risk of avalanche

events in South Carolina. The

United States avalanche hazard is

limited to mountainous western

states including Alaska, as well as

some areas of low risk in New

England.

Avalanche hazard was not

considered in the South Carolina

State Hazard Mitigation Plan.

Drought YES Review of the SC

State Hazard

Mitigation Plan

Review of

Previous

Occurrences

from NCDC

Review of

information from

the SC

Climatology

Office

Droughts are evaluated in SC

State Hazard Mitigation Plan.

According to NCDC, there have

been 64 drought occurrences

between 1950 and 2010 in the

state of South Carolina. Most of

the USC DRU campuses have

experienced drought conditions.

The SC Climatology Office

reported maximum temperatures

for each county well over 100

degrees Fahrenheit throughout

the planning area.

Hailstorm YES Review of SC

State Hazard

Mitigation Plan

Review of FEMA’s

Multi-Hazard

Identification

and Risk

Assessment

Review of NOAA

NCDC Storm

Events Database

Hail events are discussed in the

state plan.

NCDC reports 4,221 hailstorm

events (0.75 inch sized hail to

2.75 inches) in South Carolina

between 1958 and March 2010.

Heat Wave YES Review of NOAA

NCDC Storm

Events Database

Review of the SC

State Hazard

Mitigation Plan

NCDC reported 24 extreme heat

events between 1950 and March

2010 in South Carolina.

The SC State Hazard Mitigation

Plan includes Extreme Heat as a

hazard.



4:8


Natural

Hazards

Considered

Was this

hazard

identified as

significant

enough to be

addressed in

the plan?

(Yes or No)

How was this

determination

made?


made?

Hurricane and

Tropical Storm

YES Review of SC

State Hazard

Mitigation Plan

Analysis of NOAA

historical tropical

cyclone tracks

and National

Hurricane Center

Website

Review of NOAA

NCDC Storm

Events Database

Review of

historical

presidential

disaster

declarations

FEMA Hazus-MH

storm return

periods

Hurricane and tropical storm

events are evaluated in the state

plan.

NCDC reported 42 Hurricane and

Tropical Storm events in the

state of South Carolina between

1950 and March 2010.

NOAA’s NHC historical records

indicate every USC DRU campus

has been affected by a hurricane

or tropical storm event.

Three out of eight disaster

declarations affecting the USC

DRU counties, five are directly

related to hurricane and tropical

storm events.

The 50-year return period peak

gust for hurricane and tropical

storm events is between 58 mph

(Upstate campus) and 101 mph

(Baruch).

Lightning YES Review of SC

State Hazard

Mitigation Plan

Review of FEMA’s

Multi-Hazard

Identification

and Risk

Assessment

Review of NOAA

NCDC Storm

Events Database,

NOAA lightning

statistics

Lightning events are discussed in

the state plan.

NCDC reported 391 lightning

events in South Carolina between

1950 and March 2010. These

events have resulted in a

recorded 23 deaths, 92 injuries

and several million in property

damage.

Tornado YES Review of SC

State Hazard

Mitigation Plan

Review of FEMA’s

Multi-Hazard

Identification

and Risk

Assessment

Tornado events are discussed in

the SC State Hazard Mitigation

Plan.

NCDC reported 924 tornado



events resulted in 56 reported

deaths, 1,303 injuries, and



4:9


Natural

Hazards

Considered

Was this

hazard

identified as

significant

enough to be

addressed in

the plan?

(Yes or No)

How was this

determination

made?


made?

Review of NOAA

NCDC Storm

Events Database

several million in property

damage.

Severe

Thunderstorm

YES Review of SC

State Hazard

Mitigation Plan

Review of FEMA’s

Multi-Hazard

Identification

and Risk

Assessment

Review of NOAA

NCDC Storm

Events Database

Thunderstorm events are

discussed in the SC State Hazard

Mitigation Plan.

NCDC reports 7,373

thunderstorm events in South

Carolina between 1950 and

March 2010. These events

resulted in several million in

property damages.

Winter Storm

and Freeze

YES Review of SC

State Hazard

Mitigation Plan

Review of FEMA’s

Multi-Hazard

Identification

and Risk

Assessment

Review of

historical

presidential

disaster

declarations.

Review of NOAA

NCDC Storm

Events Database

Winter Storms including snow

storms and ice storms are

evaluated in the state plan.

NCDC reported 226 snow and ice



events resulted in 2 reported

deaths, 24 injuries and several

million in damages.

Of the eight disaster declarations

affecting the USC DRU counties,

two were directly to winter storm

events.

HYDROLOGIC HAZARDS

Dam and Levee

Failure

NO Review of SC

State Hazard

Mitigation Plan

USC Committee

input

Dam Failure is discussed in the

state plan.

USC Committee were not aware

of any dams that would affect the

USC DRU campuses. Further, this

hazard was classified as a man-

made hazard though may be

triggered by a natural event.



4:10


Natural

Hazards

Considered

Was this

hazard

identified as

significant

enough to be

addressed in

the plan?

(Yes or No)

How was this

determination

made?


made?

Erosion YES Review of SC

State Hazard

Mitigation Plan

Review of FEMA’s

Multi-Hazard

Identification

and Risk

Assessment

Coastal erosion is discussed in

the state plan but only for coastal

areas (no discussion of riverine

erosion).

Flood YES Review of SC

State Hazard

Mitigation Plan

Review of

historical

disaster

declarations

Review of NOAA

NCDC Storm

Events Database

Review of FEMA

DFIRM flood data

The flood hazard is thoroughly

discussed in the state plan.

Two out of eight Presidential

Disaster Declarations were flood-

related.

NCDC reported 820 flood events

in South Carolina between 1950

and March 2010. These events in

total caused 8 reported deaths,

19 injuries, and over $1billion in

property damages (2010 dollars).

Not all campuses have digital

flood data available. A

preliminary visual assessment

indicates that flood may be an

issue on some campuses.

Storm Surge YES Review of SC

State Hazard

Mitigation Plan

Review of NOAA

NCDC Storm

Events Database

Storm surge is not discussed in

the state plan.

Six surge events were reported

for the state of South Carolina by

NCDC between 1950 and March

2010. Three of these affected

Georgetown County, a USC DRU

participating campus is located.

Given the coastal location of

some campuses, Storm Surge is

a significant hazard.

GEOLOGIC HAZARDS

Earthquake YES Review of SC

State Hazard

Mitigation Plan

USGS

Earthquake

Earthquake events are discussed

in the state plan.

Earthquakes have occurred in

and around the State of South

Carolina in the past. The state is



4:11


Natural

Hazards

Considered

Was this

hazard

identified as

significant

enough to be

addressed in

the plan?

(Yes or No)

How was this

determination

made?


made?

Hazards Program

web site

Review of the

National

Geophysical Data

Center

Review of FEMA’s

Multi-Hazard

Identification

and Risk

Assessment

affected by the Charleston and

the New Madrid (near Missouri)

Fault lines which have generated

a magnitude 8.0 earthquake in

the last 200 years.

Over 1,000 events are known to

have occurred in the state

according to the National

Geophysical Data Center (1886

to 1985). Sixty-seven of these

events affected a USC DRU

county. The greatest MMI

reported was an 8.

According to USGS seismic

hazard maps, the peak ground

acceleration (PGA) with a 10%

probability of exceedance in 50

years across the state of South

Carolina is at least 4%g and goes

to the maximum of 15%g. FEMA

recommends that earthquakes be

further evaluated for mitigation

purposes in areas with a PGA of

3%g or more.

Expansive Soils NO Review of SC

State Hazard

Mitigation Plan

Review of FEMA’s

Multi-Hazard

Identification

and Risk

Assessment

Review of USDA

Soil Conservation

Service’s Soil

Survey

Expansive soils are not identified

in the state plan.

According to FEMA and USDA

sources, a majority of the

planning areas have clays with

little to no swelling potential.

Landslide NO Review of SC

State Hazard

Mitigation Plan

Review of USGS

Landslide

Incidence and

Landslide events are discussed in

the state plan.

USGS landslide hazard maps

indicate “high susceptibility with

low to moderate incidence” in the

Upstate area of the state. A



4:12


Natural

Hazards

Considered

Was this

hazard

identified as

significant

enough to be

addressed in

the plan?

(Yes or No)

How was this

determination

made?


made?

Susceptibility

Hazard Map

Review of the

South Carolina

Geological

Survey (SCGS)

majority of the state received a

low incidence rating.

Information provided by SCGS

indicated that no major landslide

events have occurred in the state

(no loss of life or property

damage) and no recording

mechanisms are in place to

capture minor events.

Land

Subsidence/

Sinkholes

NO Review of SC

State Hazard

Mitigation Plan

The state plan indicates that

there are no known sinkhole

occurrences in the state.

Tsunami NO Review of SC

State Hazard

Mitigation Plan

Review of FEMA’s

Multi-Hazard

Identification

and Risk

Assessment

Review of FEMA

“How-to”

mitigation

planning

guidance

(Publication 386-

2,

“Understanding

Your Risks –

Identifying

Hazards and

Estimating

Losses).

Tsunamis are discussed in the

state plan.

No record exists of a catastrophic

Atlantic basin tsunami impacting

the mid-Atlantic coast of the

United States.

Tsunami inundation zone maps

are not available for communities

located along the U.S. East

Coast.

FEMA mitigation planning

guidance suggests that locations

along the U.S. East Coast have a

relatively low tsunami risk and

need not conduct a tsunami risk

assessment at this time.

Volcano NO Review of SC

State Hazard

Mitigation Plan

Review of USGS

Volcano Hazards

Program web site

There are no active volcanoes in

South Carolina.

No volcanoes are located

remotely near the state.



4:13


Natural

Hazards

Considered

Was this

hazard

identified as

significant

enough to be

addressed in

the plan?

(Yes or No)

How was this

determination

made?


made?

OTHER HAZARDS

Dam and Levee

Failure

NO Review of SC

State Hazard

Mitigation Plan

USC Committee

input

Dam Failure is evaluated for the

state.

No known dams are known to

affect the USC campuses.

Therefore, this hazard was

omitted.

Hazardous

Materials

Incident

NO USC Committee

input

The USC DRU plan only includes

natural hazards. Man-made

hazards are addressed in other

university planning documents.

Public Health

Emergency

NO Input from USC

DRU Committee





Sea Level Rise YES Review of the SC

State Hazard

Mitigation Plan

Input from USC

DRU Committee

Sea Level Rise is not discussed in

the state plan.

The USC DRU Committee would

like Sea Level included and data

exists to complete the analysis

and vulnerability assessment.

Terror Threat NO Input from USC

DRU Committee





Wildfire YES Review of SC

State Hazard

Mitigation Plan

Review of

Southern Wildfire

Risk Assessment

(SWRA) Data

Review of the SC

Division of Forest

Resources

website

Wildfires are discussed in the

state plan.

A preliminary review of SWRA

data indicates that is wildfire risk

on many of the USC campuses.

According to the North Carolina

Division of Forest Resources,

each USC DRU campus has had

historical wildfire events.

Wildfire hazard risks will increase

as low-density development

along the urban/wildland

interface increases.



4:14

The following hazards were identified for the USC DRU plan based on the information provided

above and are subsequently described below in Table 4.3:

Table 4.3: USC DRU HAZARDS ATMOSPHERIC HAZARDS GEOLOGIC HAZARDS

Drought Earthquake

Extreme Heat Landslide

Hail

Hurricane and Coastal Storm Wind OTHER HAZARDS

Lightning Sea Level Rise

Severe Thunderstorm Wildfire Tornado

Winter Storm and Freeze

HYDROLOGIC HAZARDS

Coastal Erosion

Flood

Storm Surge

The description of the following hazards provides an overview of each hazard and it’s affect on the

state. In the subsequent section, Section 5: Hazard Analysis, the impact of each hazard on each

regional campus location is addressed.

Background

A drought occurs when a prolonged period of less than normal precipitation results in a serious

hydrologic imbalance. Drought is a natural climatic condition caused by an extended period of

limited rainfall. High temperatures, high winds and low humidity can worsen drought conditions,

and can make areas more susceptible to wildfire. Human demands and actions can also hasten

drought-related impacts. Humans may also alleviate drought impacts by reduced water use.

Common effects of drought include crop failure, water supply shortages, and fish and wildlife

mortality.

Droughts are frequently classified as one of following four types: meteorological, agricultural,

hydrological or socio-economic. Meteorological droughts are typically defined by the level of

“dryness” when compared to an average, or normal amount of precipitation over a given period of

time. Agricultural droughts relate common characteristics of drought to their specific agricultural-

related impacts. Hydrological drought is directly related to the effect of precipitation shortfalls on

surface and groundwater supplies. Human factors, particularly changes in land use, can alter the

hydrologic characteristics of a basin. Socio-economic drought is the result of water shortages that

limit the ability to supply water-dependent products in the marketplace.

Figure 4.1 shows the Palmer Drought Severity Index (PDSI) Summary Map for the United States

from 1895 to 1995. PDSI drought classifications are based on observed drought conditions and

range from -0.5 (incipient dry spell) to -4.0 (extreme drought). As can be seen, the Eastern United

States has historically not seen as many significant long-term droughts as the Central and Western

regions of the country.



4:15

Figure 4.1: Palmer Drought Severity Index Summary Map for the U.S.

Source: National Drought Mitigation Center (data for 1895 to 1995)

Location and Spatial Extent

Drought typically impacts a large area that cannot be confined to any geographic boundaries.

However, some regions of the United States are more susceptible to drought conditions than

others. According to the Palmer Drought Severity Index (PDSI) Summary Map for the United

States, South Carolina is in a zone of less than 5 percent to 9.99 percent PDSI less than or equal to

-3 (-3 indicating severe drought conditions). This indicates that drought conditions are a relatively

low to moderate risk for South Carolina. It is assumed that the entire state is exposed to this

hazard and that the spatial extent of that impact is large. It is important to note that drought

conditions typically do not cause significant damage to the built environment. Drought effects are

most directly felt by agricultural sectors, but at times may also cause community-wide impacts as a

result of acute water shortages (regulatory use restrictions, drinking water supply and salt water

intrusion).

Historical Occurrences

The most recent recorded drought cycle in South Carolina was in 2009, which affected nine

counties. This event ended in December when most of the state received 150 percent to 300

percent of their normal rainfall amounts between November and December. As with any drought

event, the governor and the Department of Natural Resources urged water use restrictions.

Notable Drought Events in South Carolina



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February through November 1925: The drought of 1925 caused the state to experience rainfall

deficits reaching 18.23 inches. The growing season alone had a recorded 12.41-inch rain deficit.

Livestock water was scarce, deep wells went dry and hydroelectric power was non-existent.

January through December 1954: Total statewide precipitation for that year was a mere 32.96

inches, which set the current record for driest year ever recorded in the state. An excessively hot

summer only exacerbated its impact. According to National Weather Service reports, the crop yield

was only 10 percent of its 10-year average production rate.

May through August 1993: Many locations in South Carolina broke records during the 1993

drought. For example, in July of 1993, Greenville-Spartanburg Airport recorded the hottest and

driest month on record. Nine daily record high temperatures were also set at the Greenville-

Spartanburg Airport during July 1993. Only 0.75" of rain was recorded during July 1993 making it

the driest July on record since 0.80'" in July 1977. Similar records were set at locations around the

state. The drought and record heat cost the State a total of $2251 million crop losses, including

$63.9 million for corn, $55.1 million for vegetables and fruits, $47.2 million for tobacco, $31.7

million for cotton and $27.8 million for soybeans. The drought, which started at the height of the

crop growing season in May and June, devastated South Carolina pastures and hay production. The

total loss for livestock, hay and pasture was estimated at $34.7 million.

March through May, 1995: Below normal rainfall from March through May reduced the potential

wheat yield approximately 30 percent, causing an estimated $20 million in crop damages and

losses. Water use was restricted at a few locations in the southeastern part of state.

1998–2002. The drought resulted in significantly reduced streamflows across the state. The

hydrologic-drought impacted water supplies, irrigation capacity and many lake-related businesses,

including golf courses. In addition, the drought caused numerous agricultural problems. For

example, the drought significantly contributed to the southern pine beetle epidemic. Trees

weakened by drought are more susceptible to the tree-killing beetles, which significantly increased

wildfire vulnerability. Agricultural impacts range from limited water for livestock, reduced feed

crops, and lowered crop quality. In 1998 and 2002, a natural disaster was declared for most of

South Carolina’s 46 counties by the United States Department of Agriculture.

Recent Drought Activity

According to NCDC records, there were forty-six drought events in South Carolina since 2001. No

fatalities, injuries, property, or crop damage were associated with these mild to moderate drought

events.

Probability of Future Events It can be expected that future drought events will continue to affect the state. Probability will vary

by campus location; thus an analysis of each campus is performed. The specific probability for each

campus can be found in Section 5: Hazard Analysis.

1 Clemson University Cooperative Extension Service



4:17

Background Extreme heat is defined as temperatures that hover 10 degrees or more above the average high

temperature for the region and that last for an extended period of time. A heat wave may occur

when temperatures hover 10 degrees or more above the average high temperature for the region

and last for several weeks. Humid conditions may also add to the discomfort of high temperatures.

While extreme heat does not typically affect buildings, the impact to the population can have grave

effects. Health risks from extreme heat include heat cramps, heat fainting, heat exhaustion and

heat stroke. According to the National Weather Service (which compiles data from the National

Climatic Data Center), heat is the leading weather-related killer in the United States. During the

ten-year period between 2000 and 2009 heat events killed 162 people - more people than

lightning, tornado, flood, cold, winter storm, wind and hurricane hazards. However, most deaths

are attributed to prolonged heat waves in large cities that rarely experience hot weather. The

elderly and the ill are most at-risk, along with those who exercise outdoors in hot, humid weather.

Figure 4.2 uses air temperature and humidity to determine the heat index or apparent

temperature. Table 4.4 shows the dangers associated with different heat index temperatures.

Some populations, such as the elderly and young, are more susceptible to heat danger than other

segments of the population

Figure 4.2: Heat Index Chart

Source: NOAA

EXTREME HEAT



4:18

Table 4.4: Heat Disorders Associated with Heat Index Temperature

Heat Index Temperature (Fahrenheit)

Description of Risks

80°- 90° Fatigue possible with prolonged exposure and/or physical activity

90°- 105° Sunstroke, heat cramps, and heat exhaustion possible with prolonged exposure and/or physical activity

105°- 130° Sunstroke, heat cramps, and heat exhaustion likely, and heatstroke possible with prolonged exposure and/or physical activity

130° or higher Heatstroke or sunstroke is highly likely with continued exposure

Source: National Weather Service, NOAA

Location and Spatial Extent Extreme temperatures typically impact a large area that cannot be confined to any geographic

boundaries. Therefore, it is assumed that all of the USC campuses are uniformly exposed to this

hazard and that the spatial extent of impact would be large. It is important to note however, that

extreme temperatures typically do not cause significant damage to the built environment.

Historical Occurrences According to the National Weather Service, three heat-related fatalities occurred in South Carolina

between 2000 and 2009. Table 4.5 below shows the breakdown of fatalities by year.

Table 4.5: Heat-Related Deaths in South Carolina YEAR NUMBER OF DEATHS 2000 1

2001 0

2002 0

2003 0

2004 0

2005 0

2006 0

2007 1

2008 0

2009 1

TOTAL 3

Source: National Weather Service

Probability of Future Events It can be expected that future heat events will affect the state. Probability will vary by campus

location; thus an analysis of each campus is performed. The specific probability for each campus

can be found in Section 5: Hazard Analysis.



4:19

Background Hailstorms are a potentially damaging outgrowth of severe thunderstorms. Early in the

developmental stages of a hailstorm, ice crystals form within a low-pressure front due to the rapid

rising of warm air into the upper atmosphere and the subsequent cooling of the air mass. Frozen

droplets gradually accumulate on the ice crystals until they develop to a sufficient weight and fall

as precipitation. Hail typically takes the form of spheres or irregularly-shaped masses greater than

0.75 inches in diameter. The size of hailstones is a direct function of the size and severity of the

storm. High velocity updraft winds are required to keep hail in suspension in thunderclouds. The

strength of the updraft is a function of the intensity of heating at the Earth’s surface. Higher

temperature gradients relative to elevation above the surface result in increased suspension time

and hailstone size.

Table 4.6 below shows the typical damage associated with different sizes of hail.

Table 4.6: TORRO Hailstorm Intensity Scale

Intensity

Category

Typical

Hail

Diameter

(mm)*

Probable Kinetic

Energy, J-m2 Typical Damage Impacts

H0 Hard Hail 5 0-20 No damage

H1 Potentially

Damaging 5-15 >20

Slight general damage to plants, crops

H2 Significant 10-20 >100 Significant damage to fruit, crops, vegetation

H3 Severe 20-30 >300 Severe damage to fruit and crops, damage to glass

and plastic structures, paint and wood scored

H4 Severe 25-40 >500 Widespread glass damage, vehicle bodywork

damage

H5 Destructive 30-50 >800 Wholesale destruction of glass, damage to tiled

roofs, significant risk of injuries

H6 Destructive 40-60 Bodywork of grounded aircraft dented, brick

walls pitted

H7 Destructive 50-75 Severe roof damage, risk of serious injuries

H8 Destructive 60-90 (Severest recorded in the British Isles) Severe

damage to aircraft bodywork

H9 Super

Hailstorms 75-100

Extensive structural damage. Risk of severe or

even fatal injuries to persons caught in the open

H10 Super

Hailstorms >100

Extensive structural damage. Risk of severe or

even fatal injuries to persons caught in the open

Source: http://www.torro.org.uk/site/hscale.php

HAIL



4:20

Location and Spatial Extent Hailstorms frequently accompany thunderstorms, so their locations and spatial extents coincide.

Thunderstorms are atmospheric in nature and thus threaten the entire state of South Carolina.

Therefore, hail has the potential to impact the entire state as well.

Historical Occurrences According to the National Climatic Data Center, 4,221 recorded hail events have affected South

Carolina since 1950.2 Events specific to each campus location can be found in Section 5: Hazard

Analysis.

Notable South Carolina Hail Events

April 24, 1999: A super cell thunderstorm moved through Saluda County and produced hail, some

as large as baseballs, along its entire path. Homes, buildings, farm equipment, vehicles, and crops

were damaged. The thunderstorm, including the associated hail, caused damages across a three-

mile wide swath. Property damages were estimated to be $2 million, crop damages were estimated

to be $2 million, and two injuries were reported.

August 20, 1999: Severe thunderstorms developed across the Upstate, causing damaging

straight-line winds and hail. Dime to ping-pong ball size hail was reported from near Stumphouse

Mountain to Walhalla. Various reports of hail ranging from dime to quarter size were reported from

Oconee, Anderson, Laurens and Greenville counties. Golf ball to grapefruit-size hail was reported in

Greenville and Spartanburg counties. Roof damage, as well as damage to vehicles and windows,

was widely reported. Damage estimates, considered to be quite conservative, were approximately

$1 million.

May 25, 2000: A severe thunderstorm caused straight-line winds and dime size hail in Darlington,

as well as 2-inch hailstones to the south of the city. Property damage was estimated at $150,000.

The County Agricultural Service reported several areas of crop damage near Highway 401,

estimated at $10,000. In Florence, a severe thunderstorm caused large hail and wind gusts

estimated at over 80 mph. The largest hail size was estimated at over four inches in diameter,

causing extensive damage to roof and siding. Approximately 2,000 homes were damaged, with

repair costs exceeding 6 million dollars. The storm knocked out power to over 20,000 residences.

Two injuries were reported due to broken glass impacted by hail.

Probability of Future Events It can be expected that future hail events will continue to cause minor damages to property and

vehicles throughout the state. Probability will vary by campus location; thus an analysis of each

campus is performed. The specific probability for each campus can be found in Section 5: Hazard

Analysis.

2 These hail events are only inclusive of those reported by the National Climatic Data Center (NCDC). It is likely that additional hail events have affected the state of South Carolina. As additional local data becomes available, this hazard profile will be amended.



4:21

Background Hurricanes and tropical storms are classified as cyclones and defined as any closed circulation

developing around a low-pressure center in which the winds rotate counter-clockwise in the

Northern Hemisphere (or clockwise in the Southern Hemisphere) and whose diameter averages 10

to 30 miles across. A tropical cyclone refers to any such circulation that develops over tropical

waters. Tropical cyclones act as a “safety-valve,” limiting the continued build-up of heat and

energy in tropical regions by maintaining the atmospheric heat and moisture balance between the

tropics and the pole-ward latitudes. The primary damaging forces associated with these storms are

high-level sustained winds, heavy precipitation and tornadoes. Coastal areas are also vulnerable to

the additional forces of storm surge, wind-driven waves and tidal flooding which can be more

destructive than cyclone wind.

The key energy source for a tropical cyclone is the release of latent heat from the condensation of

warm water. Their formation requires a low-pressure disturbance, warm sea surface temperature,

rotational force from the spinning of the earth and the absence of wind shear in the lowest 50,000

feet of the atmosphere. The majority of hurricanes and tropical storms form in the Atlantic Ocean,

Caribbean Sea and Gulf of Mexico during the official Atlantic hurricane season, which encompasses

the months of June through November. The peak of the Atlantic hurricane season is in early to

mid-September and the average number of storms that reach hurricane intensity per year in this

basin is about six (6).

Figure 4.3 shows for any particular location what the chance is that a tropical storm or hurricane

will affect the area sometime during the Atlantic hurricane season. (Land is outlined in black,

showing Florida and the South Carolina coast in the top left quadrant.) This illustration was created

by the National Oceanic and Atmospheric Administration’s Hurricane Research Division using data

from 1944 to 1999 and counting hits when a storm or hurricane was within approximately 100

miles (165 km) of each location.

HURRICANE AND TROPICAL STORM



4:22

Figure 4.3: Empirical Probability of a Named Hurricane or Tropical Storm

Source: National Oceanic and Atmospheric Administration, Hurricane Research Division

As an early hurricane develops, barometric pressure (measured in millibars or inches) at its center

falls and winds increase. If the atmospheric and oceanic conditions are favorable, it can intensify

into a tropical depression. When maximum sustained winds reach or exceed 39 miles per hour, the

system is designated a tropical storm, given a name, and is closely monitored by the National

Hurricane Center in Miami, Florida. When sustained winds reach or exceed 74 miles per hour the

storm is deemed a hurricane. Hurricane intensity is further classified by the Saffir-Simpson Scale,

which rates hurricane intensity on a scale of 1 to 5, with 5 being the most intense. The Saffir-

Simpson Scale is shown in Table 4.7.

The Saffir-Simpson Scale categorizes hurricane intensity linearly based upon maximum sustained

winds, barometric pressure and storm surge potential, which are combined to estimate potential

damage. Categories 3, 4, and 5 are classified as “major” hurricanes, and while hurricanes within

this range comprise only 20 percent of total tropical cyclone landfalls, they account for over 70

Table 4.7: Saffir-Simpson Scale

CATEGORY MAXIMUM SUSTAINED WIND SPEED (MPH)

MINIMUM SURFACE PRESSURE (MILLIBARS)

STORM SURGE (FEET)

1 74–95 Greater than 980 3–5

2 96–110 979–965 6–8

3 111–130 964–945 9–12

4 131–155 944–920 13–18

5 155 + Less than 920 19+

Source: National Hurricane Center



4:23

percent of the damage in the United States. Table 4.8 describes the damage that could be

expected for each category of hurricane.

Damage during hurricanes may also result from spawned tornadoes, storm surge and inland

flooding associated with heavy rainfall that usually accompanies these storms.

Location and Spatial Extent South Carolina remains one of them most vulnerable states in the U.S. to hurricanes and tropical

storms. Fourteen hurricanes have made landfall along the South Carolina coast since 1900.

According to the National Hurricane Center HURDAT data, there were seventy (70) land falling

hurricanes or tropical storm in South Carolina between 1900 and 2009. Between 1984 and 2010,

the USC DRU counties received five presidential disaster declarations specifically for hurricanes and

tropical storms, out of eight total declarations. The last reported hurricane or tropical storm-related

presidential disaster declaration was in 2004. A major hurricane has not impacted the state in

several years.

According to Figure 4.1, the empirical probability of a tropical storm or hurricane affecting the state

of South Carolina is between 12 and 36 percent each hurricane season. As indicated in the figure,

coastal areas of South Carolina are a greater risk to hurricanes and tropical storms than the inland

areas. This estimated probability is fairly consistent with observed historical storm data provided by

NOAA’s National Hurricane Center and the South Carolina Office of Emergency Management.

Table 4.8: Hurricane Damage Classifications

STORM

CATEGORY

DAMAGE

LEVEL DESCRIPTION OF DAMAGES

PHOTO

EXAMPLE

1 MINIMAL No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Also, some coastal flooding and

minor pier damage.

2 MODERATE Some roofing material, door, and window damage. Considerable damage to vegetation, mobile homes, etc. Flooding damages piers and

small craft in unprotected moorings may break their moorings.

3 EXTENSIVE

Some structural damage to small residences and utility buildings, with a minor amount of curtain wall failures. Mobile homes are destroyed. Flooding near the coast destroys smaller structures, with larger

structures damaged by floating debris. Terrain may be flooded well inland.

4 EXTREME

More extensive curtain wall failures with some complete roof structure

failure on small residences. Major erosion of beach areas. Terrain may be flooded well inland.

5 CATASTROPHIC

Complete roof failure on many residences and industrial buildings. Some

complete building failures with small utility buildings blown over or

away. Flooding causes major damage to lower floors of all structures near the shoreline. Massive evacuation of residential areas may be required.

Sources: National Hurricane Center; Federal Emergency Management Agency



4:24

Historical Occurrences Information in this subsection was collected and adapted from National Hurricane Center, National

Climatic Data Center and National Weather Service historical records in addition to the South

Carolina Hazard Mitigation Plan, South Carolina Emergency Management, and local information.

Since 1850, 70 hurricane or tropical storm tracks have passed through South Carolina.3 This

includes: zero (0) Category 5 hurricanes; one (1) Category 4 hurricanes; four (4) Category 3

hurricanes; six (6) Category 2 hurricanes; seventeen (17) Category 1 hurricanes; and forty-two

(42) tropical storms. Tracks that affected each USC regional campus are highlighted in Section 5,

including the date of occurrence, maximum wind speed, and category based on the Saffir-Simpson

Scale.

Details of the most notable hurricane events in South Carolina history are presented below.

Notable Hurricane Events in South Carolina

Great Sea Island Storm of 1893 (August 27–28, 1893): One of the deadliest hurricanes to

strike the United States, this storm made landfall in Georgia at high tide bringing a tremendous

storm surge that created a “tidal wave” effect that swept over and submerged whole islands. The

storm’s north-northeast track through the South Carolina midlands brought winds of between 96

mph and 125 mph, with maximum winds of 125 mph in the Beaufort area and up to 120 mph in

Charleston. Major damages were reported as the storm moved north near Columbia and then

northeast through the remainder of the state, causing between 2,000 and 2,500 deaths, an

estimated $10 million in damages, and leaving 20,000 to 30,000 victims homeless.

Hurricane Hazel (October 15, 1954): Hazel made landfall in South Carolina as a Category 3

hurricane near Little River bringing tides of up to 16.9 feet. The storm caused 95 deaths in North

and South Carolina. Approximately $27 million in damages was reported. Hurricane Hazel is

considered one of the most severe storms to hit South Carolina to date.

Hurricane Gracie (September 29, 1959): Gracie, a Category 3 hurricane, made landfall at St.

Helena Island with winds of 140 mph, moving northwest before weakening to a tropical storm as it

passed through Columbia and turned north-northwest on a path into North Carolina. Beach tides

reached nearly six feet above normal. Several fatalities, as well as property damage, were reported

along the southern coastal area. Heavy crop damage occurred, and moderate to heavy flooding

was reported due to six to eight inches of rainfall.

Hurricane Hugo (September 21, 1989): Hugo, a Category 4 hurricane, made landfall at Isle of

Palms, South Carolina with sustained winds of 140 mph and wind gusts exceeding 160 mph. Hugo

is the costliest storm in South Carolina history, causing over $8 billion in damages to property and

crops in the United States and the first major hurricane to strike the state since Gracie in 1959.

Total damages, including those that occurred in Puerto Rico and the Caribbean, exceeded 10 billion

dollars. Hurricane Hugo resulted in 35 storm-related fatalities, twenty of which occurred in South

Carolina. Seven of the South Carolina fatalities occurred in mobile home parks northwest of

Charleston. The strongest winds passed over the Francis Marion National Forest between Bulls Bay

and the Santee River. The Forest Service estimated that timber losses exceeded $100 million.

While the most severe winds occurred to the northeast of Charleston, the city was hard hit.

Charleston City Hall and the fire station lost their roofs and over 4,000 historic properties were

damaged. Coastal storm surge reached 20 feet in some areas, making it the highest ever recorded

in the state. Folly Beach was among the most significantly impacted coastal communities.

3 These storm track statistics do not include tropical depressions or extra tropical storms. Though these related hazard events are less severe in intensity, they may indeed cause significant local impact in terms of rainfall and high winds.



4:25

Approximately 80 percent of the homes were destroyed. Sullivan’s Island and the Isle of Palms

were also severely damaged. Numerous homes were knocked off their foundations and boats in the

local marina were tossed into a 50 foot high pile of debris. Severe inland wind damage occurred as

winds gusting to 109 mph at Sumter were reported. The hurricane exited the state just north of

Rock Hill, causing significant damage in Charlotte, North Carolina. South Carolina received a

Presidential Disaster Declaration for this event.

Hurricane Fran (September 5, 1996): Although Hurricane Fran skirted the South Carolina coast

before making landfall at the entrance of the Cape Fear River in North Carolina, it triggered the

evacuation of 500,000 tourists in the coastal areas of both states, creating the largest peacetime

evacuation in U.S. history. Wind gusts of 60 mph were reported along the Horry County coast. In

Georgetown County, 57 mph winds in the City of Georgetown contributed to $150,000 in county

government infrastructure damage. Eleven evacuation shelters housed 5,400 people. One death

was attributed to the storm. In Horry County, agricultural losses of $19.8 million were reported,

with corn, tobacco and sweet potato crops hardest hit. Downed trees caused power outages

affecting about 60,000 customers. Horry County reported property losses totaling over $1 million,

including $448,000 at North Myrtle Beach, $341,000 at Myrtle Beach, $42,000 at Surfside Beach,

$46,000 at Garden City Beach, and $135,000 in unincorporated areas. South Carolina received a

Presidential Disaster Declaration for this event.

Hurricane Bonnie (August 26, 1998): The center of Hurricane Bonnie came within 70 miles of

the Horry County coast as the storm tracked north during the afternoon and early evening. Wind

reports were as high as 82 mph at the Cherry Grove pier and 76 mph at the Myrtle Beach Pavilion.

Reported rainfall was between two and four inches. Downed trees and power lines caused some

structural damages. Estimated property damages were reported to be $3.8 million and the State of

South Carolina received a federal disaster declaration.

Hurricane Floyd (September 15, 1999): Hurricane Floyd weakened to a Category 3 hurricane

as it approached the southeast Georgia and southern South Carolina coasts on the morning of

September 15. The storm skirted the coast, its center moving northeast about 60 miles offshore

late in the afternoon and early evening as it took a more north and northeast course toward North

Carolina. Sustained winds of tropical storm force were reported from Savannah, Georgia to

Charleston with wind gusting to hurricane force strength in the Charleston area. The highest

recorded sustained wind speed was 58 mph in downtown Charleston, with gusts reaching 85 mph.

Rainfall was heavy along coastal counties as 12 inches of rain fell in Georgetown County. A

reported 18 inches fell in eastern Horry County, causing major flooding along the Waccamaw River

in and around the City of Conway for a month. Waves were reported to be 15 feet at Cherry Grove

Pier, where damage was the greatest. Tides exceeded three feet above normal with a maximum

tidal height of 10.66 feet in the City of Charleston. Minor to moderate beach erosion occurred along

the South Carolina coast. Many businesses and homes suffered major damage, with thousands of

homes experiencing at least some minor damage in Charleston County, causing approximately

$10.5 million in damage. In Horry County, approximately 400 homes and numerous roads were

inundated for over one month following the storm. Beaufort County reported $750,000 damage

with Berkeley and Dorchester counties reporting $500,000 each. Over 1,000 trees were blown

down, knocking out power to over 200,000 customers across the southern coast. In Myrtle Beach,

the tree and sign damage was reported to reach approximately $250,000. In Williamsburg County,

total damage estimates due to the high winds and rain reached approximately $650,000. In

Florence County, high winds downed trees, caused power outages and resulted in $150,000 in

property damages. Total estimated property damages for the affected counties totaled

approximately $17 million. While Hurricane Floyd did not make landfall in South Carolina, it

resulted in the largest peacetime evacuation in the state’s history. It is estimated that between

500,000 and one million people evacuated the coast. South Carolina received a Presidential

Disaster Declaration for this event.



4:26

Recent Hurricane and Tropical Storm Activity

South Carolina has been affected by four hurricanes or tropical storms since 2001. These events

account for three injuries and $23.42 million in property damage for the state of South Carolina

(Hazards Research Lab, 2006). Only two of these systems caused serious damage to people and

property in South Carolina. Hurricane Charley hit Florida in August 2004 as a category four

hurricane, but weakened as it left Florida’s east coast. Taking a northerly track, Charley made a

second landfall near Cape Romain as a weak category one hurricane. Nearly 180,000 people

evacuated Horry County in advance of the storm. Charley brought down trees, damaged roofs, and

flooded coastal areas around the Grand Strand. More than 65,000 residents lost power and

insurance claims totaling $5 million along the grand strand were reported (NCDC Storm Data

Online, 2006).

Tropical Storm Gaston impacted Berkeley, Charleston, and Dorchester Counties on August 29,

2004, causing $16.6 million dollars in property damage in Charleston and Berkeley Counties (NCDC

Storm Data Online, 2006). Gaston came ashore near Bulls Bay with sustained 70 mph winds, which

knocked down numerous trees and large limbs. Major damage was reported to over 3000

structures and power loss to over 150,000 people. A storm surge of 4 to 4.5 feet caused localized

flooding.

Tropical Storm Frances passed through South Carolina in early September of 2004. The state

received a presidential disaster declaration for this event. Areas around Caesar’s Head and Rich

Mountain received over 12 inches of rain from the storm. According to the National Weather

Services, a reported 45 tornadoes in South Carolina were associated with this storm.

Tropical Storm Hannah made landfall on September 6, 2008, impacting Myrtle Beach and the

North Carolina-South Carolina border. Hannah brought substantial rain, strong winds, and storm

surge to South Carolina.

Probability of Future Events It can be expected that future hurricane and tropical storm events will affect the state. Probability

will vary by campus location; thus an analysis of each campus is performed. The specific

probability for each campus can be found in Section 5: Hazard Analysis.



4:27

Background Lightning is a discharge of electrical energy resulting from the buildup of positive and negative

charges within a thunderstorm, creating a “bolt” when the buildup of charges becomes strong

enough. This flash of light usually occurs within the clouds or between the clouds and the ground. A

bolt of lightning can reach temperatures approaching 50,000 degrees Fahrenheit. Lightning rapidly

heats the sky as it flashes but the surrounding air cools following the bolt. This rapid heating and

cooling of the surrounding air causes the thunder which often accompanies lightning strikes. While

most often affiliated with severe thunderstorms, lightning may also strike outside of heavy rain and

might occur as far as 10 miles away from any rainfall.

According to FEMA, lightning injures an average of 300 people and kills 80 people each year in the

United States. NOAA’s National Weather Service reported 42 deaths and 58 injuries from lightning

for the ten year average between 2000 and 2009. Of these, fourteen occurred in South Carolina

(Table 4.9). Direct lightning strikes also have the ability to cause significant damage to buildings,

critical facilities and infrastructure largely by igniting a fire. Lightning is also responsible for igniting

wildfires that can result in widespread damages to property.

Table 4.9: Lightning Deaths in South Carolina YEAR NUMBER OF DEATHS 2000 2

2001 1

2002 2

2003 0

2004 2

2005 1

2006 2

2007 2

2008 2

2009 0

TOTAL 14


Location and Spatial Extent Lightning occurs randomly, in very small geographic areas. Therefore it is impossible to predict

where it will strike. However, as indicated in Figure 4.4 below, lighting occurs more frequently

along the coast at 8-10 cloud-to-ground lightning occurrences (flashes per square miles per year).

This then diminishes as you move further inland, leveling off at 3 to 4 flashes per square mile per

year.

Figure 4.3 shows a lightning flash density map for the years 1997-2007 based upon data provided

by Vaisala’s U.S. National Lightning Detection Network (NLDN®).

LIGHTNING



4:28

Figure 4.4: Lightning Flash Density in the United States

Source: NOAA, HRD; Vaisala U.S. National Lightning Detection Network

Historical Occurrences According to the National Climatic Data Center, there have been a total of nine 391 lightning

events recorded in South Carolina since 1950.4

Notable Lightning Events in South Carolina

August 23, 1995: The First Recruit Training Battalion, stationed on Paris Island in Beaufort

County, had been ordered to seek shelter and were walking in platoon formation toward a covered

area when lightning struck, killing one soldier and injuring six others.

June 29, 1998: Three women were crossing a road in Murrells Inlet when they were struck by

lightning, hospitalizing two of them.

August 16, 1998: A couple was struck by lightning near 13th hole at Colonial Charters Golf

Course in Horry County. Although the woman was successfully revived, the man died from the

strike.

4 These lightning events are only inclusive of those reported by the National Climatic Data Center (NCDC). It is likely that additional lightning events have occurred in the state of South Carolina. As additional local data becomes available, this hazard profile will be amended.



4:29

August 27, 1999: Three people were hit by lightning while visiting the River Banks Zoo in

Richland County. The victims were taken to nearby hospitals and released the next day.

June 21, 2001: Lightning struck an apartment complex in Myrtle Beach, igniting a fire. Residents

in the building's 14 apartments were forced to relocate after a Horry County code enforcer deemed

the building uninhabitable. Damages were estimated at $20,000.

June 24, 2001: Lightning struck a transformer at a manufacturing plant in Cherokee County in the

Town of Gaffney, shutting it down for more than 24 hours. This forced shutdown resulted in

approximately 1,000 employees unable to work and caused $1 million in damages.

February 22, 2003: A home was struck by lightning that caused a fire resulting in $70,000 worth

of damage.

June 11, 2003: Lightning struck a home starting a fire that caused $55k in damage.

July 21, 2003: Lightning struck a home in Spring Valley at 411 Bridgecrest Drive and caused

$175,000 in damage.

August 14, 2005: Lightning caused a home fire at 204 Upland Trail that caused $300k worth of

damage.

June 12, 2006: Lightning struck a tree and ran through the ground into the home starting a fire in

the home in the Woodcreek Farms Subdivision.

June 11, 2009: Lightning struck a home and ignited a fire which destroyed it. The home was

located at 150 Rivendale Drive. Lightning struck a home at 38 Shoreline Drive and ignited a fire

which destroyed it.

July 26, 2010: WIS TV reported a home destroyed from a fire caused by lightning on Ripplerock

road.

June 28, 2011: A mid-afternoon thunderstorm produced lightning that struck an Oak tree at Allen

Benedict Court on Harden Street where 5 landscape and maintenance workers were sitting. One

worker was taken to the hospital with non-life threatening injuries. The others were treated and

released.

Probability of Future Occurrences It can be expected that future lightning events will continue to cause minor damages to property

and vehicles throughout the state. Probability will vary by campus location; thus an analysis of

each campus is performed. According to NOAA, South Carolina experienced an average of 2-16

lightning flashes per square kilometer per year between 1997 and 2007. Coastal areas generally

have a greater threat than inland areas. The specific probability for each campus can be found in

Section 5: Hazard Analysis.



4:30

Background According to the National Weather Service, more than 100,000 thunderstorms occur each year,

though only about 10 percent of these storms are classified as “severe.” A severe thunderstorm

occurs when the storm produces one of three elements: 1) Hail of three-quarters of an inch; 2)

Tornado; 3) Winds of at least 58 miles per hour.

Although thunderstorms generally affect a small area when they occur, they are very dangerous

because of their ability to generate tornadoes, hailstorms, strong winds, flash flooding and

damaging lightning. While thunderstorms can occur in all regions of the United States, they are

most common in the central and southern states because atmospheric conditions in those regions

are most ideal for generating these powerful storms.

Three conditions need to occur for a thunderstorm to form. First, it needs moisture to form clouds

and rain. Second, it needs unstable air, such as warm air that can rise rapidly (this often referred

to as the “engine” of the storm). Third, thunderstorms need lift, which comes in the form of cold or

warm fronts, sea breezes, mountains, or the sun’s heat. When these conditions occur

simultaneously, air masses of varying temperatures meet, and a thunderstorm is formed. These

storm events can occur singularly, in lines, or in clusters. Further, they can move through an area

very quickly or linger for several hours.

Figure 4.5 illustrates thunderstorm hazard severity based on the annual average number of days

with a thunderstorm event.

SEVERE THUNDERSTORMS

Figure 4.5: Average Number of Days with Thunderstorms

Source: NOAA



4:31

Straight-line Wind

Straight-line winds, which in extreme cases have the potential to cause wind gusts that exceed 100

miles per hour, are responsible for most thunderstorm wind damage. One type of straight-line

wind, the downburst, can cause damage equivalent to a strong tornado and can be extremely

dangerous to aviation.

Location and Spatial Extent Thunderstorm are atmospheric and thus occur almost anywhere. As can be seen in Figure 4.4

above, South Carolina is one of the more vulnerable states in the U.S. to thunderstorm events. A

majority of state experiences 60 days with a thunderstorm event, while the most northern part

experiences 50 days per year. In the southeast, thunderstorms typically occur in the afternoon,

especially in the summer months. As heat and moisture builds in the atmosphere throughout the

day, it needs a release for of the built-up energy resulting in a thunderstorm. Thunderstorms vary

tremendously in terms of size, location, intensity and duration but are considered frequent

occurrences throughout South Carolina, especially in coastal areas. It is assumed that all of the

USC campuses are exposed to severe thunderstorms.

Historical Occurrences According to the National Climatic Data Center, 7,373 thunderstorm wind events have been

reported in South Carolina since 1950. Specific historical events on each campus are described in

the proceeding section: Hazard Analysis.

Probability of Future Events It can be expected that future thunderstorm events will continue to cause minor damages to

property and vehicles throughout the state. Probability will vary by campus location; thus an

analysis of each campus is performed. The specific probability for each campus can be found in

Section 5: Hazard Analysis.



4:32

Background A tornado is a violent windstorm characterized by a twisting, funnel-shaped cloud extending to the

ground. Tornadoes are most often generated by thunderstorm activity (but sometimes result from

hurricanes and other tropical storms) when cool, dry air intersects and overrides a layer of warm,

moist air forcing the warm air to rise rapidly. The damage caused by a tornado is a result of the

high wind velocity and wind-blown debris, also accompanied by lightning or large hail. According to

the National Weather Service, tornado wind speeds normally range from 40 to more than 300 miles

per hour. The most violent tornadoes have rotating winds of 250 miles per hour or more and are

capable of causing extreme destruction and turning normally harmless objects into deadly missiles.

Each year, an average of over 800 tornadoes is reported nationwide, resulting in an average of 80

deaths and 1,500 injuries (NOAA, 2002). The National Weather Service reported an average from

2000 to 2010 of 63 deaths annually.

Tornadoes are more likely to occur during the months of March through June and can occur at any

time of day, but are likely to form in the late afternoon and early evening. Most tornadoes are a

few dozen yards wide and touch down briefly, but even small short-lived tornadoes can inflict

tremendous damage. Highly destructive tornadoes may carve out a path over a mile wide and

several miles long.

The destruction caused by tornadoes ranges from light to inconceivable depending on the intensity,

size and duration of the storm. Typically, tornadoes cause the greatest damage to structures of

light construction such as residential homes (particularly mobile homes). The Fujita-Pearson Scale

for Tornadoes was developed to measure tornado strength and associated damages and was used

prior to 2005 (Table 4.10). Tornado magnitudes that were determined in 2005 and later were

determined using the Enhanced Fujita Scale (Table 4.11)

TORNADOES

Table 4.10: Fujita-Pearson Scale for Tornadoes (Effective prior to 2005)

F-SCALE NUMBER

INTENSITY PHRASE

WIND SPEED (MPH)

TYPE OF DAMAGE DONE

F0 GALE 40–72 Some damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages to sign boards.

F1 MODERATE 73–112

The lower limit is the beginning of hurricane wind speed; peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the roads; attached garages may be destroyed.

F2 SIGNIFICANT 113–157

Considerable damage. Roofs torn off frame houses; mobile

homes demolished; boxcars pushed over; large trees snapped or uprooted; light object missiles generated.

F3 SEVERE 158–206 Roof and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted.

F4 DEVASTATING 207–260 Well-constructed houses leveled; structures with weak foundations blown off some distance; cars thrown and large

missiles generated.

F5 INCREDIBLE 261–318

Strong frame houses lifted off foundations and carried considerable distances to disintegrate; automobile sized missiles fly through the air in excess of 100 meters; trees debarked; steel re-enforced concrete structures badly damaged.



4:33

According to the NOAA Storm Prediction Center (SPC), the highest concentration of tornadoes in

the United States has been in Oklahoma, Texas, Kansas and Florida respectively. Although the

Great Plains region of the Central United States does favor the development of the largest and

most dangerous tornadoes (earning the designation of “tornado alley”), Figure 4.6 shows tornado

activity in the United States based on the number of recorded tornadoes per 1,000 square miles.

The tornadoes associated with tropical cyclones are most frequent in September and October when

the incidence of tropical storm systems is greatest. This type of tornado usually occurs around the

perimeter of the storm, and most often to the right and ahead of the storm path or the storm

F6 INCONCEIVABLE 319–379

These winds are very unlikely. The small area of damage they

might produce would probably not be recognizable along with the mess produced by F4 and F5 wind that would surround the F6

winds. Missiles, such as cars and refrigerators would do serious secondary damage that could not be directly identified as F6 damage. If this level is ever achieved, evidence for it might only be found in some manner of ground swirl pattern, for it may never be identifiable through engineering studies.

Source: The Tornado Project, 2002

Table 4.11: Fujita-Pearson Scale for Tornadoes (Effective 2005 and later)

EF-SCALE NUMBER

INTENSITY PHRASE

3 SECOND GUST (MPH)

TYPE OF DAMAGE DONE

F0 GALE 65–85 Some damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages to sign boards.

F1 MODERATE 86–110

The lower limit is the beginning of hurricane wind speed; peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the roads; attached garages may be destroyed.

F2 SIGNIFICANT 111–135

Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted; light object missiles

generated.

F3 SEVERE 136–165 Roof and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted.

F4 DEVASTATING 166–200 Well-constructed houses leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated.

F5 INCREDIBLE Over 200

Strong frame houses lifted off foundations and carried considerable distances to disintegrate; automobile sized missiles fly through the air in excess of 100 meters; trees debarked; steel re-enforced concrete structures badly damaged.




4:34

center as it comes ashore. These tornadoes commonly occur as part of large outbreaks and

generally move in an easterly direction.

Figure 4.6: Tornado Activity in the United States

Source: Federal Emergency Management Agency

Waterspouts

Waterspouts are weak tornadoes that form over warm water and are most common along the Gulf

Coast and southeastern states. Waterspouts occasionally move inland, becoming tornadoes that

can cause damage and injury. However, most waterspouts dissipate over the open water

threatening only marine and boating interests. Typically a waterspout is weak and short-lived, and

because they are so common, most go unreported unless they cause damage.

Location and Spatial Extent Tornadoes occur throughout the state of South Carolina. Tornadoes typically impact a relatively

small area; however, events are completely random and it is not possible to predict specific areas

that are more susceptible to tornado strikes over time. Therefore, it is assumed that all of South

Carolina, and thus all of the USC campuses, are exposed to this hazard.



4:35

Historical Occurrences The National Climatic Data Center reported 924 tornadoes in South Carolina between 1950 and

March 2010. During this time, it reported 56 deaths and 1,303 injuries as a result of the tornadoes.

The National Weather Service, three deaths have occurred in South Carolina between 2000 and

2009 (Table 4.12).

Table 4.12: Tornado Deaths in South Carolina YEAR NUMBER OF DEATHS 2000 1

2001 0

2002 0

2003 0

2004 1

2005 0

2006 0

2007 1

2008 0

2009 0

TOTAL 3


All campuses should be considered equally exposed to tornado events.

Probability of Future Events It can be expected that future tornado events will continue to cause minor damages to property

and vehicles throughout the state. Probability will vary by campus location; thus an analysis of

each campus is performed. The specific probability for each campus can be found in Section 5:

Hazard Analysis.



4:36

Background Severe winter storms may include snow, sleet, freezing rain, or a mix of these wintry forms of

precipitation. Blizzards, the most dangerous of all winter storms, combine low temperatures, heavy

snowfall, and winds of at least 35 miles per hour, reducing visibility to only a few yards. Ice storms

occur when moisture falls and freezes immediately upon impact on trees, power lines,

communication towers, structures, roads and other hard surfaces. Winter storms and ice storms

can down trees, cause widespread power outages, damage property, and cause fatalities and

injuries to human life.

A winter storm can range from a moderate snow over a period of a few hours to blizzard conditions

with blinding wind-driven snow that lasts for several days. Some winter storms may be large

enough to affect several States, while others may affect only a single community. Many winter

storms are accompanied by low temperatures and heavy and/or blowing snow, which can severely

impair visibility.

Winter storm events may include snow, sleet, freezing rain, or a mix of these wintry forms of

precipitation. Sleet is a raindrop that freezes into an ice pellet formation before reaching the

ground, where it usually bounces upon hitting the surface and does not stick to objects. However,

sleet can accumulate like snow and cause a hazard to motorists. Freezing rain is rain that falls to

the ground when the temperature is below freezing, forming a glaze of ice on roadways and other

surfaces. An ice storm occurs when freezing rain falls and freezes immediately upon impact. Even

small accumulations of ice can cause a significant hazard, especially on power lines, roads, and

trees.

A freeze event is weather marked by low temperatures below the freezing point (zero degrees

Celsius or thirty-two degrees Fahrenheit). Freeze events are particularly dangerous as they are the

second biggest killer among natural hazards (extreme heat being first). Further, agricultural

production can be seriously affected when temperatures remain below the freezing point for an

extended period of time, particularly in areas when vulnerable crops or livestock are located.

Location and Spatial Extent South Carolina’s climate varies across the state. The western portion of the state is more

susceptible to winter weather and often experiences winter weather during the winter months. The

eastern portion, however, is much less susceptible to winter weather, making these areas less

adept in dealing with such situations. Of the planning area counties, Spartanburg, Union, and

Lancaster Counties have the highest number of reported events and damage. When such events do

occur, regardless of the location, the effects will be felt over a widespread area. The effects of

extreme cold temperatures will be primarily limited to the elderly and homeless populations, with

occasionally minor, sporadic property damages.

Deep freezes occasionally occur in South Carolina. Typically, these events cause minimal impact

outside of agricultural losses and related economic industries (including commercial nurseries).

USC does not have any agricultural programs that would be affected by deep freeze events.

Historical Occurrences The National Climatic Data Center reported 232 winter storm events in South Carolina between

1950 and March 2010 which includes winter storm, snow, freezing rain, and sleet events. Sixty-one

of these events were reported in the planning area counties where USC DRU campuses reside.

WINTER STORM AND FREEZE



4:37

These events resulted in approximately $174,230,000 (2010 dollars) in damage. It should be noted

that since these are regional occurrences and reported as such, some double counting may occur.

Notable Winter Storm Events in South Carolina

February 8-11, 1973: A snowstorm of historic proportions impacted the state, leaving behind a

record 24 inches of snow in some areas. Snowdrifts of up to eight inches were recorded.

Approximately 30,000 motorists were stranded on the state’s highways—many rescued by

helicopter. Eight exposure-related fatalities were reported. Over 200 buildings, in addition to

thousands of awnings and carports, collapsed under the weight of the snow. Property and road

damages as well as the cost of snow removal and rescue operations were estimated to total

approximately $30 million.

March 13, 1993: This winter storm, which possessed an extremely low atmospheric pressure,

passed across South Carolina bringing damaging winds, recorded snowfalls of as much as 11.5 feet

in portions of the mountains, and snow flurries on the southeast tip of the coast. Preliminary

damage assessments at the time were estimated at over $22 million.

March 8, 1996: This event brought record low temperatures that caused a recorded $20 million

loss to the peach crop in the upper portion of the state.

January 22-29, 2000: Low pressure rapidly deepened near the Carolina coast, wrapping

abundant moisture back across the piedmont of the Carolinas. By the time snow ended,

accumulations ranged from 12 to 20 inches. Due to the heavy wet snow, numerous power outages

occurred and buildings collapsed. On January 29, a weakening low pressure system in the Ohio

River Valley, and a low pressure system along the Gulf Coast, coupled with arctic air across the

Carolinas, resulted in an icy mess throughout Upstate South Carolina. Precipitation, which briefly

began as a light mixture of sleet and snow, quickly turned to freezing rain, resulting in a glaze 1/4

to 1/2 inch thick on exposed surfaces. Power outages were common across the region, especially in

the Lower Piedmont from Abbeville to Greenwood. South Carolina requested $9.2 million in federal

disaster aid to remove snow and downed trees. A total of 38 counties received a Presidential

Disaster Declaration.

There have been four severe winter events in South Carolina since 2001. These winter storms

account for two fatalities, twenty-four injuries and $129.8 million in property damage (NCDC Storm

Data Online, 2006).

December 4, 2002: An ice storm causing $100 million in property damages affected a majority of

the counties in the state. Abbeville, Anderson, Cherokee, Chester, Greenville, Oconee, Pickens,

Greenwood, Laurens, Spartanburg, Union, and York Counties suffered most of the losses from this

event, which included ice accumulations up to 1½ inch in some areas. Hundreds of thousands of

homes were without power, many for as long as two weeks in some areas.

January 25-27, 2004: A severe winter storm affected all but five counties statewide with ice and

snow. Damages to property primarily in the Pee Dee region-- Darlington, Dillon, Florence, Marion,

Marlboro, and Williamsburg Counties—were estimated at over $26 million (NCDC Storm Data

Online, 2006). Major power outages occurred due to falling limbs and many homes were without

power for a week. This incident prompted the first disaster declaration in two years.

February 2004: A late winter mix affecting all of the Upstate counties and those in the northern

piedmont of the state caused one fatality and almost $2 million in property damages. Total snowfall

accumulation was up to 22 inches in some areas and caused one fatal vehicle accident in which

thousands of people became stranded on I-77.



4:38

December 2005: A winter storm producing ice and snow in the upstate counties of Abbeville,

Anderson, Cherokee, Chester, Greenville, Laurens, Oconee, Pickens, Spartanburg, Union, and York.

This event caused almost $1.5 million in property damage due to power outages and housing unit

damage from falling limbs and trees. There were four (indirect) fatalities associated with carbon

monoxide poisoning due to indoor generator use in Anderson. This winter storm resulted in a

Presidential disaster declaration.

Probability of Future Events It can be expected that future winter storm and freeze events will continue to cause minor

damages to property and vehicles throughout the state. Probability will vary by campus location;

thus an analysis of each campus is performed. The specific probability for each campus can be

found in Section 5: Hazard Analysis.



4:39

Background Erosion is the gradual breakdown and movement of land due to both physical and chemical

processes of water, wind, and general meteorological conditions. Natural, or geologic, erosion has

occurred since the Earth’s formation and continues at a very slow and uniform rate each year.

There are two types of soil erosion: wind erosion and water erosion. Wind erosion can cause

significant soil loss as winds blowing across sparsely vegetated or disturbed land can pick up and

carry soil particles through the air, thus displacing them. Water erosion can occur over land or in

streams and channels. Water erosion that takes place over land may result from raindrops, shallow

sheets of water flowing off the land, or shallow surface flow, which is concentrated in low spots.

Major storms such as hurricanes may cause significant coastal erosion by combining high winds

with heavy surf and storm surge.

An area’s potential for erosion is determined by four factors: soil characteristics, vegetative cover,

climate or rainfall, and topography. Soils composed of a large percentage of silt and fine sand are

most susceptible to erosion. As the clay and organic content of these soils increase, the potential

for erosion decreases. Well-drained and well-graded gravels and gravel-sand mixtures are the least

likely to erode. Coarse gravel soils are highly permeable and have a good capacity for absorption,

which can prevent or delay the amount of surface runoff. Vegetative cover can reduce erosion by

shielding the soil surface from falling rain, absorbing water from the soil, and slowing the velocity

of runoff. Runoff is also affected by the topography of the area including size, shape and slope. The

greater the slope length and gradient, the more potential an area has for erosion. Climate can

affect the amount of runoff, especially the frequency, intensity and duration of rainfall and storms.

When rainstorms are frequent, intense, or of long duration, erosion risks increase. Seasonal

changes in temperature and rainfall amounts define the period of highest erosion risk.

Death and injury are not associated with erosion; however, it can cause the destruction of buildings

and infrastructure and represents a major threat to the local economies of communities that rely

on the financial benefits of recreational areas such as rivers or beaches.

Location and Spatial Extent All of the coastal areas in South Carolina are susceptible to the coastal erosion hazard. These areas

are subject to repeated, episodic coastal erosion events that threaten public and private property.

However, some areas, such as Myrtle Beach, replenish the sand lost to coastal erosion through re-

nourishment projects, thus greatly reducing the effects.

Historical Occurrences The severity of coastal erosion is typically measured through a quantitative assessment of annual

shoreline change for a given beach cross-section of profile (feet or meters per year) over a long

period of time. Erosion rates vary as a function of shoreline type and are influenced primarily by

episodic events, but can be used in land use and hazard management to define areas of critical

concern. Unfortunately, there is no uniform erosion rate database or GIS data layer that defines

erosion rates or such areas of critical concern for the state’s shoreline. A review of the national

Climatic Data Center does not indicate any significant erosion events that would impact USC

campuses.

COASTAL EROSION



4:40

Probability of Future Events It can be expected that coastal erosion events will continue to occur along the coast. Probability

will vary by campus location; thus an analysis of each campus is performed. The specific




4:41

Background Flooding is the most frequent and costly natural hazard in the United States, a hazard that has

caused more than 10,000 deaths since 1900. Nearly 90 percent of presidential disaster

declarations result from natural events where flooding was a major component.

Floods are generally the result of excessive precipitation, and can be classified under two

categories: general floods, precipitation over a given river basin for a long period of time; and flash

floods, the product of heavy localized precipitation in a short time period over a given location. The

severity of a flooding event is determined by the following: a combination of stream and river basin

topography and physiography; precipitation and weather patterns; recent soil moisture conditions;

and the degree of vegetative clearing.

General floods are usually long-term events that may last for several days. The primary types of

general flooding include riverine, coastal and urban flooding. Riverine flooding is a function of

excessive precipitation levels and water runoff volumes within the watershed of a stream or river.

Coastal flooding is typically a result of storm surge, wind-driven waves and heavy rainfall produced

by hurricanes, tropical storms and other large coastal storms. Urban flooding occurs where

manmade development has obstructed the natural flow of water and decreased the ability of

natural groundcover to absorb and retain surface water runoff.

Most flash flooding is caused by slow-moving thunderstorms in a local area or by heavy rains

associated with hurricanes and tropical storms. However, flash flooding events may also occur from

a dam or levee failure within minutes or hours of heavy amounts of rainfall, or from a sudden

release of water held by a retention basin or other stormwater control facility. Although flash

flooding occurs most often along mountain streams, it is also common in urbanized areas where

much of the ground is covered by impervious surfaces. Flash flood waters move at very high

speeds—“walls” of water can reach heights of 10 to 20 feet. Flash flood waters and the

accompanying debris can uproot trees, roll boulders, destroy buildings, and obliterate bridges and

roads.

The periodic flooding of lands adjacent to rivers, streams and shorelines (land known as floodplain)

is a natural and inevitable occurrence that can be expected to take place based upon established

recurrence intervals. The recurrence interval of a flood is defined as the average time interval, in

years, expected between a flood event of a particular magnitude and an equal or larger flood. Flood

magnitude increases with increasing recurrence interval.

Floodplains are designated by the frequency of the flood that is large enough to cover them. For

example, the 10-year floodplain will be covered by the 10-year flood and the 100-year floodplain

by the 100-year flood. Flood frequencies such as the 100-year flood are determined by plotting a

graph of the size of all known floods for an area and determining how often floods of a particular

size occur. Another way of expressing the flood frequency is the chance of occurrence in a given

year, which is the percentage of the probability of flooding each year. For example, the 100-year

flood has a 1 percent chance of occurring in any given year. The 500-year flood has a 0.2 percent

chance of occurring in any given year.

Location and Spatial Extent Several areas throughout the state of South Carolina are subject to flooding. Location varies

substantially by campus and is discussed extensively in Section 5: Hazard Analysis using maps and

narrative. In addition to riverine flooding, areas closer to the coast general are very flat and close

FLOOD



4:42

to sea level. This results in extensive “ponding” due to the lack of elevation gradients to facilitate

adequate stormwater runoff. Further, its water supply lies just below the surface of the ground.

Regardless of the location, major rainfall events sometimes leave rainwater nowhere to drain,

causing flooding near rivers and canals as well as in urban areas due to poor percolation rates and

the low elevations (particularly in western parts of the county). Coastal flooding along the shoreline

is typically associated with tidal surge caused by land-falling tropical storms and hurricane events.

Historical Occurrences According to the National Climatic Data Center, there have been 777 reported flood events

throughout the State between 1950 and March 2010. Of these, 215 occurred in the planning area

counties where USC campuses reside. These events accounted for nearly $108 million (2010

dollars) in damages. Obviously this makes flooding a frequent and costly hazard for the state.

Of the flood events recorded, six events are considered notable based on the following criteria:

extent, number of deaths, and amount of property damage sustained. Prior to 1993, four particular

floods in the 20th century are remembered for causing numerous deaths, significant property

damage, and/or Presidential Disaster Declarations.

The following information highlights flood events that are detailed in the state hazard mitigation

plan.

June 6, 1903 (“The Great Pacolet Flood”): “The Great Pacolet Flood” of 1903 resulted in the

greatest loss of life from riverine flooding during the 20th century in the state. Sixty-five (65)

people drowned. According to a National Weather Service Monthly Weather Review report, the

water rose so rapidly that the land near the river was covered by 41 feet of water within 40

minutes. Homes, churches and businesses, including 7 cotton mills, 13 railroad bridges, and 17

farm houses were destroyed. 4,300 people were put out of work due to the flood. Railway traffic

was disrupted and the textile communities of Pacolet in Spartanburg County and Clinton in Laurens

County were devastated by this event. Flood damages were also reported along other streams in

the northwestern section of the state. Damages were estimated to be approximately $3,866,000.

August 26–30, 1908 (Riverine Flooding): This storm event formed in the Gulf of Mexico and

moved slowly northeastward across the state. This event is considered to be the most extensive

flood in South Carolina on record, as all the major rivers in the state exceeded flood stage by

between nine and 22 feet. Heavy damages to property and crops were reported.

September 21–24, 1928 (Riverine and Coastal Flooding): This flood event was caused by an

unnamed hurricane. Severe flooding was reported statewide, with rainfall totals ranging from 10 to

12 inches. Many bridges were destroyed, and roads and railways were impassable. Property losses

reached an estimated $4 to $6 million.

October 22, 1990 (Severe Storm Flooding): The worst riverine flooding in recent times

occurred in October 1990 as a result of rains from Tropical Storms Klaus and Marco. Eleven of the

state’s fifteen river basins exceeded flood stage. Within a 24-hour period, areas in Orangeburg,

Sumter, Kershaw, Lancaster, and Chesterfield counties experienced as much as 10-15 inches of

rain, which exceeded the 50-100 year events. This flood event resulted in a Presidential Disaster

Declaration (DR-881) for 13 counties in South Carolina, including Aiken, Calhoun, Cherokee,

Darlington, Edgefield, Florence, Kershaw, Lancaster, Lee, Orangeburg, Spartanburg, Sumter and

Union.

April 5, 1993 (Coastal Flooding): The northeast coastal beaches experienced a combination of

high spring tides and strong onshore winds on this date, causing considerable beach erosion and

coastal flooding. Many dune crossovers, walkways, and staircases were destroyed in the Myrtle-



4:43

Crescent Beach area in Horry County. North Myrtle Beach lost three to four feet of dunes. Property

damages, totaling $7,716,247 based on current cost estimates, were reported.

June 27, 1994 (Flash Flooding): Within a 24-hour period, heavy rain caused flash flooding in

portions of central South Carolina. Severe flash flooding in Lexington County flooded roadways and

culverts, and breached a millpond dam on Red Bank Creek that resulted in two additional

downstream dam failures. Approximately $7,330,363 in current estimated property damages

occurred, primarily along Red Bank Creek and Congaree Creek, as floodwaters washed trees and

other debris into sheds, homes, and vehicles. Two people were rescued when the car they were

riding in was swept off of Highway 6 near Red Bank Creek, shortly after the failure of Red Bank Mill

Dam.

October 3, 1994 (Coastal and Flash Flooding): Record-breaking rainstorms, with unofficially

recorded rainfall exceeding 13 inches within 24-hour period in Beaufort County, impacted the

South Carolina coast. A 24-hour rain total of 11.5 inches was recorded at Honey Horn Plantation,

located on northern Hilton Head Island. This rainfall event broke the official all-time rainfall record

at that location. There were also scattered areas of flash flooding in the county, followed by severe

coastal flooding. Heaviest flooding was reported on Hilton Head Island. Floodwaters covered many

streets, damaged more than 147 homes, six government buildings, 36 businesses and at least 45

cars. Approximately 37 roads washed out or were damaged. The area’s oyster beds were closed

from October 3 to October 24 due to effluent releases. Several Low Country sewage treatment

plants reported flooding problems and more than 3,012 consumers lost electrical power. Based on

current cost estimations, $1,466,073 in property damages was reported. In Colleton County,

$1,466,073 in property damages (based on current cost estimations) was reported when roads

flooded and numerous homes were damaged by the floodwaters. Rainfall amounts of four to eight

inches fell within a 24-hour period across much of Charleston County. Runoff from heavy rains,

high tides and strong winds caused significant flooding over much of the coastal areas of the

county, especially in the City of Charleston and over most of the nearby barrier islands. Buildings

and homes were damaged, sewers backed up, roads flooded, and cars were inundated by the

floodwaters. The county experienced $439,822 in property damages and $8,796 in crop damages,

based on current cost estimates. There was an additional $73,304 in property damages reported

due to flash flooding.

October 13, 1994 (Flash and Coastal Flooding): Bands of heavy precipitation produced four to

10 inches of rain along the South Carolina coast, causing varying degrees of flash flooding in 40

counties. Flash flooding caused $2,932,000 in property damages and $11,720 in crop damages,

based on current dollar estimations. The heaviest rainfall and the worst flooding occurred in

Charleston, southern Colleton County, Beaufort County and southern Jasper County. Numerous

roads were flooded and/or washed away. There was considerable flooding of homes and businesses

throughout the area. Beach erosion was also noted at several locations along the South Carolina

coast. Beaufort County was heavily impacted, reporting 218 homes/villas/apartments damaged or

destroyed. Fifteen businesses reported flood damage. Eight wastewater treatment plants and two

golf courses were heavily damaged. Moderate beach erosion was reported along the south coast,

with 200,000 cubic yards of sand lost on Hilton Head Island. Coastal flooding caused $36,651,824

in property damages and $73,260 in crop damages based on current dollar estimates.

August 24–31, 1995 (Flooding and Flash Flooding): Slow moving bands of heavy rain, formed

from remnants of Tropical Storm Jerry, began moving into South Carolina, dumping an initial three

to five inches of rain. As additional bands moved across the state, flash flooding developed in

various areas and roads became flooded and impassable. Approximately 11 inches fell within a 48-

hour period in Abbeville County, washing out bridges and closing roads. Flooding from the heavy

rains disrupted traffic on Hilton Head Island and St. Helena Island, covering roads and bridges and

flooding some homes. Already saturated ground produced flash flooding in some areas, as well as



4:44

flooding in areas where flash flooding had occurred earlier. As rivers and creeks continued to rise,

at least six bridges were destroyed in Laurens County, including the Highway 418 Bridge across the

Enoree River. Several small dams broke, including one in Union County where a wall of water

rushed across a road. Throughout much of eastside of Greenville, Greer, Taylors, and the western

side of Spartanburg, storm water totals of approximately 15 inches were reported. Two deaths

were reported in the Greenville-Spartanburg area and one death was reported in Gaffney. Flooding

along the Enoree River, Abner Creek, Brushy Creek, Gilder Creek, and Horseman Creek in the

eastern half of Greenville and the western side of Spartanburg County was the worst in recent

memory. The South Carolina Department of Transportation estimated between $4 and $5 million in

damages to roads and bridges. The current total cost estimates for the damages caused by this

extended flood event equal $18,717,472.

August 14–15, 1998 (Flash Flooding): A flash flood in Spartanburg County rapidly developed

following four to five inches of rainfall, which fell during a very short time period. The flash flooding

affected several creeks around the City of Spartanburg and moved southward to Roebuck, Walnut

Grove and Pauline. Most of the damages occurred along Timms Creek and Lawson Fork Creek.

Roads were washed out and several people had to be rescued from their homes. A country club

experienced severe damage and a restaurant was destroyed. Property damages of $3,145,092,

based on current cost estimates, were reported. For a second consecutive night, on August 15, a

flash flood occurred in Spartanburg County. The primary flooding occurred along Fairforest Creek

and affected the communities located on the west side of the city. An area motel was flooded,

requiring the evacuation of the residents. This second flood event caused additional property

damages of $629,018, based on current cost estimates.

Recent Flood Activity

Five flood events have occurred in the state since 2001 that are considered significant events

(causing more than $1 million in property or crop damage). The first event was the Greater

Greenville flood of March 20, 2003, which caused $1.3 million in property damage in Greenville

and over $1.0 million in Spartanburg. Heavy overnight rainfall produced flash flooding, and

continued moderate rainfall resulted in additional flooding along many creeks and streams in areas

of Greenville County. The flooding was quite significant in Berea, Taylors, and Mauldin. In Berea,

some residents had to be rescued via canoe from their homes (NCDC Storm Data Reports Online).

Another flood event caused by heavy rainfall occurred on September 7, 2004 in Oconee and

Greenville counties causing an estimated $2.6 million in property damage and $5 million in crop

damage. Widespread flooding of creeks and streams developed across the two counties. Numerous

roads were covered with water or washed out, and the sewer systems of several communities were

damaged.

Another large flash-flooding event hit Greenville on July 29, 2004 causing $3.5 million in property

damage. A nearly stationary thunderstorm produced 4 to 9 inches of rainfall in approximately 4

hours resulting in major flooding in areas from Berea to downtown Greenville. The Reedy River

crested at 19.2 feet in downtown Greenville, the second highest level on record (NCDC Storm Data

reports Online, 2006). Several businesses and homes along the river incurred major damage,

hundreds of vehicles were damaged or destroyed, and numerous roads and bridges were damaged

or washed out. At least 30 homes were condemned (NCDC Storm Data Reports, 2006).

A flash flood on July 7, 2005 in Greenville, Pickens, and Spartanburg Counties caused $1.8 million

in property damage as more than thirty homes were inundated by floodwaters. More than 100

people had to be rescued from various locations throughout these counties as floodwaters washed

out roadways and bridges across the three counties.



4:45

The most recent flood event occurred on August 10, 2005 and caused $1.5 million in property

damage when a pond overflowed into a new subdivision in Spartanburg County, affecting fifteen

new homes.

Probability of Future Events It can be expected that future flooding events will cause damage to property and vehicles

throughout the state. Probability will vary by campus location; thus an analysis of each campus is

performed. The specific probability for each campus can be found in Section 5: Hazard Analysis.



4:46

Background Storm surge occurs when the water level of a tidally influenced body of water increases above the

normal astronomical high tide, and are most common in conjunction with coastal storms with

massive low-pressure systems with cyclonic flows such as hurricanes, tropical storms and

nor’easters. The low barometric pressure associated with these storms cause the water surface to

rise, and storms making landfall during peak tides have surge heights and more extensive flood

inundation limits. Storm surges will inundate coastal floodplains by dune overwash, tidal elevation

rise in inland bays and harbors, and backwater flooding through coastal river mouths. The duration

of a storm is the most influential factor affecting the severity and impact of storm surges.

A storm surge is often described as a wave that has outrun its generating source and become a

long period swell. It is often recognized as a large dome of water that may be 50 to 100 miles

wide and generally rising anywhere from four to five feet in a Category 1 hurricane to over 20 feet

in a Category 5 storm. The storm surge arrives ahead of the storm center’s actual landfall and the

more intense the storm is, the sooner the surge arrives. Water rise can be very rapid, posing a

serious threat to those who have not yet evacuated flood-prone areas. The surge is always highest

in the right-front quadrant of the direction in which the storm is moving. As the storm approaches

shore, the greatest storm surge will be to the north of the low-pressure system or hurricane eye.

Such a surge of high water topped by waves driven by hurricane force winds can be devastating to

coastal regions, causing severe beach erosion and property damage along the immediate shoreline.

Storm surge heights and associated waves are dependent on not only the storm’s intensity but also

upon the shape of the offshore continental shelf (narrow or wide) and the depth of the ocean

bottom (bathymetry). A narrow shelf, or one that drops steeply from the shoreline and

subsequently produces deep water close to the shoreline, tends to produce a lower surge but

higher and more powerful storm waves. The storms that generate the largest coastal storm surges

can develop year-round, but they are most frequent from late summer to early spring.

Location and Spatial Extent Areas along coasts, bays, inlets, and lakes are at risk to storm surge. The USC campuses located in

coastal areas (Baruch and Beaufort) were analyzed for surge risk. Specific information on the

locations at risk can be found in Section 5: Hazard Analysis.

Historical Occurrences The National Climatic Data Center reported just 18 events for storm surge events in the state from

1995 to March 2010. Just one of these occurred in a planning area county (Aiken County), which

does not pertain to coastal storm surge. However, hurricane and tropical storm events result in

surge and it is known hazard in the state. Specific historical occurrences are detailed for coastal

campuses in Section 5: Hazard Analysis.

Probability of Future Events It can be expected that future coastal storm surge events will cause damage to property and

coastal erosion along coastal areas in the state. Probability will vary by location; therefore, an

analysis of each campus is performed and can be found in Section 5: Hazard Analysis.

STORM SURGE



4:47

Background An earthquake is movement or trembling of the ground produced by sudden displacement of rock

in the Earth's crust. Earthquakes result from crustal strain, volcanism, landslides or the collapse of

caverns. Earthquakes can affect hundreds of thousands of square miles, cause damage to property

measured in the tens of billions of dollars, result in loss of life and injury to hundreds of thousands

of persons; and disrupt the social and economic functioning of the affected area.

Most property damage and earthquake-related deaths are caused by the failure and collapse of

structures due to ground shaking. The level of damage depends upon the amplitude and duration

of the shaking, which are directly related to the earthquake size, distance from the fault, site and

regional geology. Other damaging earthquake effects include landslides, the down-slope movement

of soil and rock (mountain regions and along hillsides), and liquefaction, in which ground soil loses

the ability to resist shear and flows much like quick sand. In the case of liquefaction, anything

relying on the substrata for support can shift, tilt, rupture or collapse.

Most earthquakes are caused by the release of stresses accumulated as a result of the rupture of

rocks along opposing fault planes in the Earth’s outer crust. These fault planes are typically found

along borders of the Earth's 10 tectonic plates. The areas of greatest tectonic instability occur at

the perimeters of the slowly moving plates, as these locations are subjected to the greatest strains

from plates traveling in opposite directions and at different speeds. Deformation along plate

boundaries causes strain in the rock and the consequent buildup of stored energy. When the built-

up stress exceeds the rocks' strength, a rupture occurs. The rock on both sides of the fracture is

snapped, releasing the stored energy and producing seismic waves, generating an earthquake.

Earthquakes are measured in terms of their magnitude and intensity. Magnitude is measured using

the Richter Scale, an open-ended logarithmic scale that describes the energy release of an

earthquake through a measure of shock wave amplitude (Table 4.13). Each unit increase in

magnitude on the Richter Scale corresponds to a 10-fold increase in wave amplitude, or a 32-fold

increase in energy. Intensity is most commonly measured using the Modified Mercalli Intensity

(MMI) Scale based on direct and indirect measurements of seismic effects. The scale levels are

typically described using roman numerals, with a I corresponding to imperceptible (instrumental)

events, IV corresponding to moderate (felt by people awake), to XII for catastrophic (total

destruction). A detailed description of the Modified Mercalli Intensity Scale of earthquake intensity

and its correspondence to the Richter Scale is given in Table 4.14.

EARTHQUAKES



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Table 4.13: Richter Scale

RICHTER

MAGNITUDES EARTHQUAKE EFFECTS

< 3.5 Generally not felt, but recorded.

3.5 - 5.4 Often felt, but rarely causes damage.

5.4 - 6.0 At most slight damage to well-designed buildings. Can cause major damage to poorly constructed buildings over small regions.

6.1 - 6.9 Can be destructive in areas up to about 100 kilometers across where people live.

7.0 - 7.9 Major earthquake. Can cause serious damage over larger areas.

8 or > Great earthquake. Can cause serious damage in areas several hundred kilometers across.


Table 4.14: Modified Mercalli Intensity Scale for Earthquakes

SCALE INTENSITY DESCRIPTION OF EFFECTS

CORRESPONDING

RICHTER SCALE MAGNITUDE

I INSTRUMENTAL Detected only on seismographs.

II FEEBLE Some people feel it. < 4.2

III SLIGHT Felt by people resting; like a truck

rumbling by.

IV MODERATE Felt by people walking.

V SLIGHTLY STRONG

Sleepers awake; church bells ring. < 4.8

VI STRONG Trees sway; suspended objects swing, objects fall off shelves.

< 5.4

VII VERY STRONG Mild alarm; walls crack; plaster falls. < 6.1

VIII DESTRUCTIVE Moving cars uncontrollable; masonry fractures, poorly constructed buildings

damaged.

IX RUINOUS Some houses collapse; ground cracks; pipes break open.

< 6.9

X DISASTROUS Ground cracks profusely; many buildings destroyed; liquefaction and landslides

widespread.

< 7.3

XI VERY DISASTROUS

Most buildings and bridges collapse; roads, railways, pipes and cables destroyed; general triggering of other

hazards.

< 8.1

XII CATASTROPHIC Total destruction; trees fall; ground rises and falls in waves.

> 8.1




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Location and Spatial Extent The greatest earthquake threat in the United States is along tectonic plate boundaries and seismic

fault lines located in the central and western states; however, the East Coast does face moderate

risk to less frequent, less intense earthquake events. Figure 4.7 shows relative seismic risk for the

United States, which indicates that the state falls between 4 percent g and 24 percent g. (Percent

g refers to the percentage of gravity which is a measure of the forces caused by the earthquake

shaking.)

Figure 4.7: United States Earthquake Hazard Map

Source: United States Geological Survey



4:50

Figure 4.8 shows major historic earthquake epicenters (magnitude 3.0 or greater on the Richter

Scale) within the state.5

Figure 4.8: Seismic Hazard Map for South Carolina

Source: United States Geological Survey

5 Figure references earthquake magnitudes up to 6.9 on the Richter Scale based on information provided by the University of

South Carolina Seismic Network. Some other official records classify the 1886 Charleston earthquake as up to a 7.3

magnitude event instead of a 6.9 magnitude event. Date of occurrence is listed Universal Coordinated Time.



4:51

Figure 4.9 shows the fault lines in South Carolina.

Figure 4.9: Fault Lines in South Carolina

Source: http://www.dnr.sc.gov/geology/earthquake.htm6

Historical Occurrences The National Geophysical Data Center has 1,086

data records of earthquake activity in the State of

South Carolina from December 16, 1811 through

June 9, 1985. During this time period, the

Modified Mercalli Scale Intensity (given in Roman

Numeral values) of these events ranged from a II

up to an X in intensity. (To help put this scale into

perspective, the devastating Charleston

earthquake of 1886 was a X.) An earthquake with

a Modified Mercalli Scale Intensity (MMI) of VI or

greater is likely to cause structural damages,

injuries and possible deaths. Events that affected

each county where a USC campus is located are

described in the Section 5: Hazard Analysis.

According to the National Geophysical Data Center,

only one significant earthquake has occurred in

South Carolina - the Charleston Earthquake of

6 Maybin, A.H., Clendenin, C.W., Jr., Assisted by Daniels, D.L., 1998, Structural features map of South Carolina: South Carolina Geological Survey General Geologic Map Series, 1p.

Photo from the Earth Science Photographs - U.S.

Geological Survey Library. Joseph K. McGregor

and Carl Abston. U.S. Geological Survey Digital

Data Series DDS-21, 1995.



4:52

1886. During this event, Horry County experienced a magnitude of VI (Strong) on the Modified

Mercalli Intensity (MMI) Scale. There have been more than two hundred minimal earthquakes

reported in South Carolina since 2001, but none of these events caused any significant damage

and many were not even strong enough to be felt by people.

Charleston Earthquake

On August 31, 1886, an earthquake occurred in Charleston, South Carolina that is considered to be

one of the most damaging earthquakes to occur in the southeast United States. This earthquake

killed 60 people and left most structures in the Charleston area damaged or destroyed, resulting in

an estimated $23 million7 in damage. Although Charleston and the cities and towns nearby

suffered most of the damage, cities located as far away as Georgia and North Carolina were

affected. According to the U.S. Geological Survey (USGS), “The total area affected by this

earthquake covered more than five million square kilometers and included distant points such as

New York City, Boston and Milwaukee in the United States, and Havana, Cuba and Bermuda. All or

parts of 30 states and Ontario, Canada, felt the principal earthquake.”

Recent Earthquake Activity

There have been more than two hundred minimal earthquakes in South Carolina since 2001. None

of these events caused any significant damage and many were not even strong enough to be felt

by people. There have been no significant earthquakes during this time period. The counties that

have had the greatest number of earthquakes during this time period are Fairfield County and

Berkeley County with one hundred thirty-four and forty-one earthquakes respectively (South

Carolina Seismic Network, 2006).

Probability of Future Events It can be expected that future earthquake events will cause minor damage to property and vehicles

throughout the state. Probability will vary by campus location; thus an analysis of each campus is

performed. The specific probability for each campus can be found in Section 5: Hazard Analysis.

7 Other sources quote South Carolina damages for this event at $5.5 million.



4:53

Background Sea Level Rise is defined by NOAA as the mean rise in sea level. It is caused by two factors: 1) as

the ocean warms, sea water expands in volume; 2) continental ice shelves melt, increasing the

amount of water in the oceans. This leads to a greater area of land being inundated by sea water.

Rising sea level contributes to the loss of coastal wetlands (which provide protective buffers from

flood events), beach erosion, population and property in low areas, coastal habitats and species.

Further, flooding and hurricane events are more severe and affect a greater area.

Given that 600 million people live in an area that is less that 10 meters (33 feet) above sea level,

and the coastal population has doubled in the last 50 years, sea level rise is a formidable threat.

Location and Spatial Extent Sea level rise is occurring along coasts across the globe. However, it does not affect areas

uniformly and will be more severe in some places. Figure 4.10 shows a hypothetical situation of

sea level rise where the sea rises at 1.0, 2.0, 4.0 and 8.0 meters. This research comes from NOAA.

As can be seen, sea level rise affects the South Carolina coast in each scenario. In Section 5, maps

depict sea level rise scenarios along the coastal USC DRU campus counties.

SEA LEVEL RISE



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Figure 4.10: Sea Level Rise in the Southeastern United States

Source: http://www.www.gfdl.noaa.gov/~tk/climate_dynamics/climate_impact_webpage.html

Historical Occurrences Sea-level rise is a slow-onset hazard that has recently been realized. No historical occurrences

have been reported in the state.

Probability of Future Events There is still much debate regarding the probability of future occurrence of sea level rise.



4:55

Background A wildfire is any fire occurring in a wildland area (i.e. grassland, forest, brush land) except for fire

under prescription.8 Wildfires are part of the natural management of forest ecosystems, but may

also be caused by human factors. Over 80 percent of forest fires are started by negligent human

behavior such as smoking in wooded areas or improperly extinguishing campfires. The second most

common cause for wildfire is lightning.

There are three classes of wildland fires: surface fire, ground fire and crown fire. A surface fire is

the most common of these three classes and burns along the floor of a forest, moving slowly and

killing or damaging trees. A ground fire (muck fire) is usually started by lightning or human

carelessness and burns on or below the forest floor. Crown fires spread rapidly by wind and move

quickly by jumping along the tops of trees. Wildland fires are usually signaled by dense smoke that

fills the area for miles around.

State and local governments can impose fire safety regulations on home sites and developments to

help curb wildfire. Land treatment measures such as fire access roads, water storage, helipads,

safety zones, buffers, firebreaks, fuel breaks and fuel management can be designed as part of an

overall fire defense system to aid in fire control. Fuel management, prescribed burning and

cooperative land management planning can also be encouraged to reduce fire hazards.

Fire probability depends on local weather conditions, outdoor activities such as camping, debris

burning, and construction, and the degree of public cooperation with fire prevention measures.

Drought conditions and other natural hazards (such as tornadoes, hurricanes, etc.) increase the

probability of wildfires by producing fuel in both urban and rural settings. Forest damage from

hurricanes and tornadoes may also block interior access roads and fire breaks, pull down overhead

power lines, or damage pavement and underground utilities.

Many individual homes and cabins, subdivisions, resorts, recreational areas, organizational camps,

businesses and industries are located within high wildfire hazard areas. The increasing demand for

outdoor recreation places more people in wildlands during holidays, weekends and vacation

periods. Unfortunately, wildland residents and visitors are rarely educated or prepared for wildfire

events that can sweep through the brush and timber and destroy property within minutes.

Location and Spatial Extent Wildfires are a substantial threat in South Carolina. The South Carolina Forestry Commission

reports that it responds to over 3,000 fires annually. Essentially all areas are susceptible to

wildfire, though highly developed areas have a fairly low risk. Wildland and areas on the wildland-

urban fringe are at the greatest risk. Drought conditions can make a fire more likely in these locations and exacerbate the severity of the fire.

Future wildfires could pose interruptions to ongoing research efforts that draw in outside area for

laboratory experiments. Human respiratory health is another related concern with regard to

wildfires occurring nearby the USC campuses.

8 Prescription burning, or “controlled burn,” undertaken by land management agencies is the process of igniting fires under selected conditions, in accordance with strict parameters.

WILDFIRE



4:56

Historical Occurrences Data was provided from the South Carolina Forestry Commission. There are 13.6 million acres of

forestland in the State of which 12.2 is commercial forestland. The Forestry Commission responds

to more than 3,000 wildland fires each year which typically burn around 20,000 acres in all. Most

of these fires (98%) are caused by human activity such as debris burning, arson, and camp fires.

The Forestry Commission also provided specific data of fires and acres burned for the Counties

where a USC campus resides between 1946 and 2009, a 63 year period. Nearly 78,000 fires

burned a combined 700,375 acres for the subject counties. This averages to 1,251 fires annually

burning a combined average of approximately 11,117 acres. Specific events by county and that

impacting the campuses are reported in Section 5: Hazard Analysis.

Probability of Future Events It can be expected that future wildfire events will occur in the proximately of USC campuses and

cause minor damage to property and vehicles throughout the state. Probability will vary by campus

location; thus an analysis of each campus is performed. Several factors influence probability

including climate and surrounding groundcover. In most cases wildfires can be contained that

greatest externality will be the secondary effects of smoke and ash in the air. The specific


Documents

ALL-HAZARDS MITIGATION PLAN HAZARD IDENTIFICATION Identification.pdf · ALL-HAZARDS MITIGATION PLAN HAZARD IDENTIFICATION The objectives of the Hazard Identification section are two-fold: