Page 9 - Yucaipa Valley Water District

THE THREAT OF EARTHQUAKE DISASTER

ShakeOut Scenario We witnessed the state’s potential for earthquake
disaster in 1994. The Northridge earthquake jolted
Southern California a mere 10 to 20 seconds, a 6.7-
magnitude blind-reverse thrust event that struck with
Researchers at the University of
brutal force, causing more than $67 billion in
Southern California have determined
widespread damage.
that the economic impact of a
projected 7.8-magnitude earthquake Homes, businesses and apartment buildings splintered
along the San Andreas Fault in
and collapsed. Aftershocks fueled the ferocity as large
Southern California would be the
patches of the region were left heavily damaged: Nine
costliest disaster in U.S. history. Here
hospitals were declared unstable.
are the numbers:
$113 billion in building damage Schools and universities were red-tagged; broken gas
and water pipes, downed utility lines, fires, and
$68 billion in business flattened bridges and overpasses left many streets
interruption impassable. The temblor shook the earth with a power

that produced the largest ground motion ever recorded
$11 billion in related costs
in an urban environment in the United States. The scope
Total Economic Impact: $192 of destruction ranks Northridge as one of the five
billion costliest natural disasters in U.S. history. i

Yet the magnitude of that quake was relatively mild
compared to what could be.
Seismologists say stress along the San Andreas fault has been building with little relief since the mid-
1800s. The next “Big One” – which could come at any moment – could be of a magnitude of 7.5 or more,
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they say. Such a quake would rip along the fault and displace it by an average of 9 feet.
“Northridge was not a big quake,” Seismologist Lucy Jones told NBC News. “… If we had the same quake
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on another fault, we’d have way more damage.” A larger quake would decimate the local economy,
she said. Businesses would close, people would not be able to get to work, and an exodus of residents
would flee, leaving the City of Angels behind for others to rebuild.

Predictions for the Future

Hurricane Katrina, so far, represents the nation’s most devastating natural disaster. Yet experts say a
7.8-magnitude earthquake in Southern California would result in even more deaths and nearly twice the
damage to area infrastructure, including buildings, critical transportation, power and water systems.
This scenario, as depicted by the “Great ShakeOut,” would “have devastating economic consequences
for the eight-county region comprising Southern California,” researchers at the University of Southern
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California determined:
Building on estimates of property damage of $113 billion and some estimates of direct business
interruption by other members of the research team…, we estimate the total business interruption
impacts at $68 billion and related costs at nearly $11 billion. This could make the ShakeOut
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Earthquake Scenario the costliest disaster in U.S. history. (Grossi 2009, Rose et al. 2009).

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Yucaipa Valley Water District - March 8, 2018 - Page 9 of 40