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Just how realistic IS California earthquake disaster
movie San Andreas? Seismologist reveals all
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In San Andreas film,Southern California
is rocked by a powerful magnitude-9.1
quake followed by even stronger
magnitude-9.6 in Northern California
U.S. Geological Survey seismologist
said earthquakes this large are near
impossible because San Andreas fault
is not long or deep enough
Seismologist Susan Hough said that
earthquake-prediction technology
hasn't advanced as far as it shows in
the film
Hough said though a tsunami hits in
the film, that wouldn't happen in reality
- but added that the fault will break
again without warning
The San Andreas Fault awakens, unleashing back-to-back jolts that leave a trail of misery from Los
Angeles to San Francisco. Skyscrapers crumble. Fires erupt. The letters of the Hollywood sign topple.
Tsunami waves swamp the Golden Gate Bridge.
Hollywood's favorite geologic bad guy is back in 'San Andreas' - a fantastical look at one of the
world's real seismic threats.
But film viewers might ask as they watch the film, just how accurate is it?
THE SAN ANDREAS FAULT
The San Andreas system in Northern California consists of five major branches with an overall length
of about 1,25O miles.
Experts say there is a 99 percent chance of a magnitude-6.7 earthquake or larger in the next 30
years in California because of the number of fault lines in the region.
The San Andreas Fault that forms the tectonic boundary between the Pacific Plate and the North
American Plate is the biggest.
The San Andreas has long been
considered one of the most dangerous
earthquake faults because of its length.
At nearly 800 miles long, it cuts through
California like a scar and is responsible for
some of the largest shakers in state
history.
In the film, opening this Friday, a
previously unknown fault near the Hoover
Dam in Nevada ruptures and jiggles the
San Andreas.
Southern California is rocked by a powerful
magnitude-9.1 quake followed by an even
stronger magnitude-9.6 in Northern
California.
The San Andreas is notorious for producing big ones,
but a magnitude-9 or larger is virtually impossible
because the fault is not long or deep enough, U.S.
Geological Survey seismologist Susan Hough told the
Associated Press.
Despite the implausible plot, however, she said the
San Andreas will indeed break again, and without
warning
The most powerful tremors in recorded history have
struck along offshore subduction zones where one
massive tectonic plate dives beneath another. The
1960 magnitude-9.5 quake off Chile is the current
world record holder.
In 2008, the USGS led a team of 300 experts that
wrote a script detailing what would happen if a
magnitude-7.8 hit the southern San Andreas. They
wanted to create a science-based crisis scenario that
can be used for preparedness drills.
The lesson: It doesn't take a magnitude-9 or greater
to wreak havoc. Researchers calculated a magnitude7.8 would cause 1,800 deaths and 50,000 injuries.
Hundreds of old brick buildings and concrete
structures and a few high-rise steel buildings would
collapse.
Computer models show the San Andreas is capable of producing a magnitude-8.3 quake, but
anything larger is dubious.
In the film, Lawrence Hayes, a fictional seismologist at California Institute of Technology, notices
spikes in 'magnetic pulses' that light up California like a Christmas tree, heralding a monster quake.
Despite a century of research, in reality earthquake prediction remains elusive. Scientists can't predict
when a jolt is coming and are generally pessimistic about ever having that ability.
Every warning sign scrutinized - animal behavior, weather patterns, electromagnetic signals,
atmospheric observations, levels of radon gas in soil or groundwater - has failed.
'We wish it were as simple as the movie portrays. It isn't. Researchers have scoured every
imaginable signal trying to find reliable precursors, but nothing has panned out,' Hough said.
The latest focus has been on creating early warning systems that give residents and businesses a
few seconds heads up after a quake hits, but before strong shaking is felt.
Japan has the most advanced seismic alert system in the world while the United States is currently
testing a prototype.
And, unlike the film, the San Andreas can't spawn tsunamis.
Most tsunamis are triggered by underwater quakes, but they can also be caused by landslides,
volcanoes and even meteor impacts.
Giant tsunami waves are formed when the Earth's crust violently shifts, displacing huge amounts of
seawater.
The larger the magnitude, the more these waves can race across the ocean without losing energy.
The San Andreas is strike-slip fault, in which opposing blocks of rocks slide past each other
horizontally.
A big San Andreas quake can spark fires and other mayhem, but it can't displace water and flood San
Francisco. Hough said the movie got one aspect right: The tide suddenly ebbing out signals a
tsunami is coming. More than 80 - mostly small - tsunamis have been observed along California's
coast in the past, triggered mainly by faraway quakes. In the movie, the scientist warned that shaking
would be felt on the East Coast. But even the largest possible San Andreas quake won't rattle the
East Coast. While seismic waves from great quakes can make the Earth reverberate like a bell, the
ringing can only be detected by sensitive instruments because it's so low. Historical accounts show
shaking from the 1906 San Andreas quake was barely felt in western Nevada and southern Oregon,
Hough said.
Questions
1.
Why is it not possible for the San Andreas to have earth quakes of magnitude 9.6?
2.
What do experts say is an actual possibility for a future San Andreas quake?
3.
Where were the most powerful tremors in recorded history, and what caused them?
4.
What is the highest magnitude quake the San Andreas is capable of producing?
5.
What is the truth regarding scientists being able to predict earthquakes?
6.
Who has the best early warning system currently?
7.
Why cant the San Andreas produce a tsunami?
8.
How many tsunamis has California had?
9.
Would the East coast really feel a quake from the San Andreas? How far would the quake be
felt?