NATURAL HAZARDS AND DISASTERS

Unit III – Chapter 4

WHAT ARE THEY?

Floods Earthquakes Hurricanes Tornadoes Volcanoes Tsunamis Avalanches

WHAT IS A NATURAL HAZARD?

Aspects of physical world that have potential to cause considerable harm to people

o a dormant volcano

WHAT IS A NATURAL DISASTER?

When a natural hazard is activated and reacts in such a way as humans and/or communities are destroyed

WHY ARE NATURAL DISASTERS TAKING A HEAVIER TOLL THESE DAYS?

Occur most often in heavily populated areas in southern hemisphere

Poorer countries with less solid infrastructure

More difficult for poorer countries (LCD and LLCD) to react quickly and compensate for loss

FACTORS USED TO C0MPARE NATURAL DISASTERS

Frequency How often a particular event is likely to occur

Duration How long an event will last

Extent How large an area or region will it effect widespread or restricted to a small area

Speed of onset How much warning will you get

Spatial dispersion Area affected by disaster – prediction of

where it will take place

Temporal spacing How hazards occur in time – hurricanes

occur in the same areas at the same time of year; while volcanoes are unpredictable

CLASSIFYING NATURAL DISASTERS

Loss of life Number of injuries Damage to property Intensity/strength of event

wind speed, Richter scale for earthquakes

Event causes other hazards – atmospheric, biologic and geologic

WHAT IS A GLOBAL HAZARD?

An event that affects people in many areas of the world

An event that has long term effects (for many years)

An event that causes permanent damage or serious contamination of the natural environment

TYPES OF NATURAL DISASTERS

Atmospheric Biological Geological

ATMOSPHERIC NATURAL DISASTERS

TYPES OF ATMOSPHERE HAZARDS/DISASTERS

Severe storm Cyclonic storm – hurricane, cyclone,

typhoon Tornado Flooding Drought Wildfire

CYCLONIC STORMS Connected with weather and climate changes normal weather patterns develop because of

differences in air masses Prevailing winds shift these air masses When two air masses collide a sharp boundary

called a front forms Rotating low pressure areas, or cells form along

storm front Depending on how different the air masses are

influences the types of storm that will develop

TROPICAL CYCLONES

Develop as the result of high temperatures and large amounts of water vapour

Develop over oceans and follow curved storm paths

Moved by prevailing winds and the Coriolis effect

Usually hit land where they cause significant destruction

THE HURRICANE

TORNADO formation of a tornado - Bing Video

HURRICANE VS TORNADO

Form over water Called hurricanes -

Atlantic; cyclones – Indian; typhoons – Pacific

Most destructive of all natural disasters

Follow curved storm paths and often end up over land

Cover extensive areas High winds, rain Extensive area so more

widespread damage

Form over land Called twisters, funnel

clouds Occur mostly in middle

latitudes with thunderstorms that are part of cyclonic storm forming on cold front

Narrow path High winds, rain Limited area so less

widespread damage

FLOODS AND FLOODING

High precipitation associated with a storm front

Rivers rise, overflow and flood adjoining lowland

Storms can cause “storm surge” which cause extensive lowland flooding

Storms can also cause mudslides

DROUGHT

Extended periods without rainfall Prolonged drought – crop failure, death i.e. Sahel area of sub-Saharan region of

Africa Desertification = productive dry land is

degraded to the point where it is no longer productive

WILDFIRE

Dry weather conditions, high winds, large forests are ideal conditions for wildfires

BIOLOGIC NATURAL HAZARDS AND DISASTERS

Millions of deaths attributed to infectious or parasitic diseases

MEASLES

Prior to 2000 – 1.2 million children died/year (textbook)

In 2008 - 164 000 measles deaths globally – nearly 450 deaths/day or 18 deaths/hour

Measles vaccination (up 72% from 2000) resulted in a 78% drop in measles deaths between 2000 and 2008 worldwide

LDCs and LLDCs – 95% of deaths

HIV

By the end of 2008 - 33.4 million people worldwide were living with HIV

2 million people died of AIDS-related illnesses.

Globally, less than 1 in 5 at risk of HIV has access to basic HIV prevention services.

Only 36% of people who needed HIV treatment had access to it by end of 2009

2010 report – significant progress is being made

HIV/AIDS progress report from 144 low- and middle-income countries in 2009: 15 countries, including Botswana, Guyana

and South Africa, were able to treat more than 80% of HIV-positive pregnant women

14 countries, including Brazil, Namibia and Ukraine, provided HIV treatment to more than 80% of HIV-positive children

8 countries, including Cambodia, Cuba and Rwanda, have achieved universal access to antiretroviral treatment (ART) for adults.

RIVER BLINDNESS

35 million people world-wide suffer from disease 140 million African people are at risk caused by a parasitical worm, onchocerca

volvulus. The worm larvae are spread by the black simulium

fly, which breeds in the high-oxygen water of fast-flowing rivers.

fly transmits disease when it bites people, making those who live or work near the rivers vulnerable.

Treatment - Mectizan®.

Ways to break the cycle of infection: reducing # of flies by spraying affected areas with

insecticide slowing fast-flowing rivers, making them unattractive

as breeding grounds reducing exposure to flies by using protective garments killing the adult worms by removing the worm 'nodules'

- difficult because infected villages are often very remote and poor, making accessible surgery difficult.

providing a yearly dose of the drug Mectizan® in affected areas.

Problems with medication Needs to be administered regularly and communally

GEOLOGIC HAZARDS AND DISTASTERS

EARTHQUAKES

Most violent and sudden Cause the highest # of deaths July 27, 1976 – Tangshan China – killed

255,000 + 665,000 injured Occur in areas of world defined by

tectonic plates Many run through highly populated

areas

AFTER EFFECTS

Collapsing buildings Breaks in communication and

transportation Electricity loss Fire Flooding Disease

MORE SEVERE EFFECTS IN LDCS AND LLDCS

High population density Substandard housing Lack relief resources

VOLCANOES

Cause fewer deaths than any other natural disaster

Slow – lots of warning Well known volcanoes – Mt. Vesuvius

(Pompeii), Mt. St. Helens (Washington State), Eyjafjallajökull (Iceland)

Hawaii has daily volcanic activity Iceland has harnessed geothermal energy

for heating and electricity generation

SLIDES AND AVALANCHES

Slide is rapid movement down a slope – rocks, soil or combination

Combination of geological factors + triggering event like heavy rain or earthquake or human effect – deforestation, clearcutting

Avalanches – rapid movement of snow and ice

TSUNAMIS

Japanese for “harbour wave” Not connected to tides – therefore not

“tidal waves” Caused by mudflows, landslides,

earthquakes or volcanoes that take place on ocean floor

Most common cause – earthquakes Devastating tsunami – Thailand,

Christmas 2004 – 230,000 deaths

THE ROLE OF HUMANS IN NATURAL DISASTERS

We are victims of natural disasters We can also cause them to be more

disastrous Clear cutting, hillside farming, urban

development

REFERENCES

http://visual.merriam-webster.com/images/plants-gardening/plants/plant/photosynthesis.jpg, retrieved March 1, 2010

http://www.allaboutgemstones.com/rock_cycle.html retrieved March 3, 2010

http://en.wikipedia.org/wiki/Earth March 3 http://www.bing.com/images/search?q=Tide&FORM=BIFD#focal

=c753352f665971332d781ca13addc07e&furl=http%3A%2F%2Flibrary.thinkquest.org%2FC003124%2Fimages%2Ftides.jpg March 3

http://www.harcourtschool.com/activity/science_up_close/314/deploy/interface.html March 3

file:///H:\My%20Pictures\Hurricane_formation.gif retrieved March 11

file:///H:\My%20Pictures\flappy_tornado_formation.jpg retrieved March 11

National Geographic websites