Seismic and Tsunami Threats to Southern California Nancy King, Ph.D. U.S. Geological Survey Pasadena...
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Seismic and Tsunami Threats to Southern California Nancy King, Ph.D. U.S. Geological Survey Pasadena Field Office Northridge earthquake 1994 Northridge
Seismic and Tsunami Threats to Southern California Nancy King,
Ph.D. U.S. Geological Survey Pasadena Field Office Northridge
earthquake 1994 Northridge earthquake, 1994 Emergency Response
Readiness Workshop Joint Forces Training Base, Los Alamitos,
California May 10, 2012
Slide 2
Plate Tectonics and Earthquakes
Slide 3
Faults and Plate Tectonics Plate motion occurs on faults.
Slide 4
What Faults Look Like After Earthquakes 1906 San Francisco
earthquake 1979 Imperial Valley earthquake Scarp of 1971 San
Fernando earthquake Photo from Finding Fault in California: An
Earthquake Tourists Guide, by Susan Elizabeth Hough Landers
earthquake, 1992
Slide 5
Faults and Shaking An earthquake is sudden slip on a fault.
This slip triggers seismic waves. These waves cause shaking and
most of the damage.
Slide 6
Seismic Waves
Slide 7
Seismogram
Slide 8
Faults and Earthquakes of the Western U.S.
Slide 9
What the San Andreas Fault Looks Like Stream offset: 420 feet
in 3800 years
Slide 10
Faults of Southern California Over 300 faults in Southern
California Only the San Andreas can have the Big One (M 7.8+) But
earthquakes on other faults can be disasters, e.g. 1994 Northridge
M 6.7 But other faults can produce damaging earthquakes
Slide 11
Magnitude and Intensity Magnitude is the maximum amplitude on a
seismogram. Worldwide neic.usgs.gov/neis/eqlists/eqstats.html Doug
Given, USGS The magnitude scale is logarithmic. Each whole number
increase is: 10 times more ground motion 32 times more energy
Intensity is the earthquakes effects, on scale of I to XII. Depends
on: Distance from earthquake Geology Type of structure Observer!
Varies from place to place.
Slide 12
Earthquake History of S. California
Slide 13
Earthquakes in California 19302007 50,000 Good seismic network
begins here. On average in southern California: Over 30 per day,
mostly not felt Magnitude 6 every 5 years Magnitude 7 every 30
years Magnitude 7.7 every 150 years We CANNOT predict these
earthquakes!
Slide 14
Earthquake Effects Aftershocks March 11, 2011 Tohoku M 9.0
earthquake and its aftershocks in the first day
Slide 15
Earthquake Effects - Structure Failure Ferndale, CA, M 7.1 1992
Life-safe Columbia, M 6.2, 1999 NOT life-safe Northridge, CA, M 6.7
1994 Performance depends on Material Construction
Earthquake Effects - Utility Line Rupture USGS Open File Report
96-263 Northridge earthquake,1994
Slide 18
Earthquake Effects - Lifelines Highways, railways, power lines,
phone lines, pipelines, and water aqueducts and pipelines all cross
the San Andreas fault
Slide 19
Earthquake Effects - Interior Damage Dr. Cindy Stern
Slide 20
Earthquake Effects Landslides and Liquefaction Landslides
Northridge, 1994 Steinbrugge Collection of the UC Berkeley
Earthquake Engineering Research Center Liquefaction Niigata, Japan,
1964
Slide 21
Earthquake Effects - Tsunamis One or more intense waves,
usually caused by an earthquake or undersea landslide. First wave
may NOT be the largest. Timing between waves may vary from minutes
to several hours apart. The danger lasts hours after the first
wave. Tsunami waves can come ashore in different ways: Wall of
water rapidly rising tide series of surf-like breakers Tsunamis can
carry boats, debris and heavy rocks. Types: Local earthquakes near
the coast where first wave can be within 10 minutes and may not be
time for a tsunami warning Pacific-wide caused by earthquakes far
away from our coast which allows time for an tsunami warning
Vulnerable areas in so. California include: LA and Long Beach
Harbor, Venice and West Los Angeles beaches. TSUNAMI WARNING
BROADCAST: Pack up your family and pets and move inland
Slide 22
Earthquake Effects Tsunami in Hawaii, 1946 Hilo, Hawaii,
1946
Slide 23
Earthquake Effects - Community Death and injury Structure
damage No power/gas Fire No water Road/rail closures Phones out No
emergency services Stranded commuters Separated families Destroyed
homes Stores closed Business losses Loss of jobs
Slide 24
The Big One The last Big One in southern California was the
Fort Tejon Earthquake of 1857, which killed 2 people. No one
remembers this earthquake. The next Big One will be different,
causing casualties and damage in now heavily populated southern
California. There will be up to 2 minutes of ground shaking.
Preparation and response are local. Its up to us.
Slide 25
Earthquake Deaths Roger Bilham, University of Colorado Japan
2011
Slide 26
Earthquake Preparedness and Response Retrofit buildings Secure
fixtures/contents Emergency plan Emergency supplies Check for
damage and injuries Follow your emergency plan Expect aftershocks
Contact insurance agent Restore documents Begin repairs Contact
FEMA Before During Drop, cover, and hold on! After
Slide 27
USGS Products CISN Display Real time earthquake alert and
notification California-Nevada Earthquake Map Earthquake
Notification System ShakeCast Situational awareness tool for
emergency responders and critical facility operators
Slide 28
USGS Products Did You Feel It?ShakeMap
Slide 29
The Take-Home Message We live in earthquake country! Its up to
each of us to prepare.