Seismic and Tsunami Threats to Southern California

Emergency Response Readiness Workshop Joint Forces Training Base, Los Alamitos, California May 10, 2012 Northridge earthquake 1994 Northridge earthquake, 1994 Nancy King, Ph.D. U.S. Geological Survey Pasadena Field Office

Plate Tectonics and Earthquakes

Faults and Plate Tectonics

Plate motion occurs on faults.

What Faults Look Like After Earthquakes Scarp of 1971 San Fernando earthquake 1906 San Francisco earthquake Photo from Finding Fault in California: An Earthquake Tourists ’ by Susan Elizabeth Hough Guide, Landers earthquake, 1992 1979 Imperial Valley earthquake

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.

Seismic Waves

Seismogram

Faults and Earthquakes of the Western U.S.

What the San Andreas Fault Looks Like Stream offset: 420 feet in 3800 years

Faults of Southern California Over 300 faults in Southern California But other faults can produce damaging earthquakes 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

Magnitude and Intensity Magnitude is the maximum amplitude on a seismogram.

The magnitude scale is logarithmic.

Each whole number increase is: 10 times more ground motion 32 times more energy Worldwide Intensity is the earthquake’s effects, on scale of I to XII. Depends on: • Distance from earthquake • Geology • Type of structure • Observer!

Varies from place to place.

Doug Given, USGS neic.usgs.gov/neis/eqlists/eqstats.html

Earthquake History of S. California

50,000 Earthquakes in California 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 1930 Good seismic network begins here.

2007 We CANNOT predict these earthquakes !

Earthquake Effects – Aftershocks March 11, 2011 Tohoku M 9.0 earthquake and its aftershocks in the first day

Earthquake Effects - Structure Failure Life-safe Ferndale, CA, M 7.1 1992 Performance depends on • Material • Construction Northridge, CA, M 6.7 1994 Columbia, M 6.2, 1999 NOT life-safe

Earthquake Effects - Falling Objects Stanford University, 1906 earthquake

Earthquake Effects - Utility Line Rupture Northridge earthquake,1994 USGS Open File Report 96-263

Earthquake Effects - Lifelines Highways, railways, power lines, phone lines, pipelines, and water aqueducts and pipelines all cross the San Andreas fault

Earthquake Effects - Interior Damage Dr. Cindy Stern

Earthquake Effects – Landslides and Liquefaction Landslides – Northridge, 1994 Liquefaction – Niigata, Japan, 1964 Steinbrugge Collection of the UC Berkeley Earthquake Engineering Research Center

Earthquake Effects - Tsunamis •

One or more intense waves, usually caused by an earthquake or undersea landslide.

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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.

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Tsunami waves can come ashore in different ways: Wall of water – rapidly rising tide – series of surf-like breakers

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Tsunamis can carry boats, debris and heavy rocks.

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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

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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

Earthquake Effects – Tsunami in Hawaii, 1946 Hilo, Hawaii, 1946

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

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.

It’s up to us.

Earthquake Deaths Japan 2011 Roger Bilham, University of Colorado

Earthquake Preparedness and Response • • • • Before Retrofit buildings Secure fixtures/contents Emergency plan Emergency supplies During – Drop, cover, and hold on!

After • • • • • • • Check for damage and injuries Follow your emergency plan Expect aftershocks Contact insurance agent Restore documents Begin repairs Contact FEMA

USGS Products CISN Display – Real time earthquake alert and notification California-Nevada Earthquake Map ShakeCast – Situational awareness tool for emergency responders and critical facility operators Earthquake Notification System

ShakeMap USGS Products Did You Feel It?

The Take-Home Message

We live in earthquake country!

It ’ s up to each of us to prepare.

Thank you!