Seismic and Tsunami Threats
to Southern California
Emergency Response Readiness Workshop
Joint Forces Training Base, Los Alamitos,
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’ Guide,
by Susan Elizabeth Hough
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
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
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 Doug
Given, USGS
Earthquake History of S. California
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
Good seismic
network begins here.
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
Ferndale, CA, M 7.1 1992
Northridge, CA,
M 6.7 1994
NOT life-safe
Performance depends on
• Material
• Construction
Columbia, M 6.2, 1999
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 –
Niigata, Japan, 1964
Landslides –
Northridge, 1994
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.
• 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
Earthquake Effects – Tsunami in Hawaii, 1946
Hilo, Hawaii, 1946
Earthquake Effects - Community
• Death and injury
• No emergency services
• Structure damage
• Stranded commuters
• No power/gas
• Separated families
• Fire
• Destroyed homes
• No water
• Stores closed
• Road/rail closures
• Business losses
• Phones out
• 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
Retrofit buildings
Secure fixtures/contents
Emergency plan
Emergency supplies
During – Drop, cover,
and hold on!
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 –
awareness tool
for emergency
responders and
critical facility
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!

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