Earthquake early warning system closer to reality for California
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Hanh Duong
VietPress USA News Agency
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Here’s
what’s really going on with that scary California earthquake advisory
October 1, 2016
Here’s
what’s really going on with that scary California earthquake advisory
If
you’re like most Californians, you’ve probably spent the last few days low-key
freaking out about the possibility of an earthquake. True,
many of us already exist at some level of generalized earthquake anxiety,
but the phrase “San Andreas fault” has shown up in the news a lot lately, and
now there’s something about an earthquake advisory being issued?!?!?
It’s
okay, though! We’re gonna explain. It turns out that it’s not really as
big of a deal as the media’s making it sound.
Basically, it all started on Monday morning, when there was a “swarm”
of 200 mostly itsy-bitsy earthquakes in the Salton Sea off of California’s
coast, just south of the big ol’ San Andreas fault. (The one that
caused the Loma Prieta quake in ’89, ICYMI.)
Risk of big earthquake on San Andreas fault rises after
quake swarm at Salton Sea http://lat.ms/2dBiVkE
That
got scientists’ attention because it’s only the third such “swarm” since
they started monitoring there in 1932, and it was one of the larger ones
so far. So there was/is some concern that these little earthquakes
might trigger a bigger quake along the San Andreas fault line —
especially since the SoCal part of the fault is as much as 180 years
overdue for a major earthquake. There hasn’t been a big tremor there
since the 1680s, and on average large quakes are supposed to hit about every
150 to 200 years.
Hence the anxiety-inducing
earthquake warning from the experts. But it turns out that even they aren’t
too sure about how big a deal this is. Initial number-crunching
suggested the risk of an earthquake before next Monday was anywhere from 1 in
100 to 1 in 3,000, up from the normal 1 in 6,000 risk without an
earthquake swarm. Thankfully, as of yesterday, the United States Geological Survey says that
the risk of a big quake (anything magnitude 7 or up) has decreased
substantially, to anywhere from 1 in 500 to less than 1 in
10,000. At the very worst, we’re looking at a 0.2% chance of
earthquake.
Earthquake early warning system closer to reality for
California
Doug Given, earthquake warning coordinator for the U.S. Geological Survey, discusses the development of the earthquake early warning system in California, as Mark Ghilarducci, director of the Governor’s Office of Emergency Services, center, and Sen. Jerry Hill, D-San Mateo, look on during a news conference Thursday, Sept. 29, 2016, in Rancho Cordova, Gov. Jerry Brown has signed legislation to develop a statewide earthquake early warning system in California, after devoting $10 million to the program in the state budget he signed this
Doug Given, earthquake warning coordinator for the U.S.
Geological Survey, discusses the development of the earthquake early warning
system in California, as Mark Ghilarducci, director of the Governor’s Office of
Emergency Services, center, and Sen. Jerry Hill, D-San Mateo, look on during a
news conference Thursday, Sept. 29, 2016, in Rancho Cordova, Gov. Jerry Brown
has signed legislation to develop a statewide earthquake early warning system
in California, after devoting $10 million to the program in the state budget he
signed this year. AP Photo/Rich Pedroncelli
A map of earthquake faults in part of Southern California is
seen as a sample of an earthquake early warning system the state that is under
development is displayed on a television monitor in the background, during a
news conference Thursday, Sept. 29, 2016, in Rancho Cordova, Gov. Jerry Brown
has signed legislation to develop a statewide earthquake early warning system
in California, after devoting $10 million to the program in the state budget he
signed this year.
A map of earthquake faults in part of Southern California is
seen as a sample of an earthquake early warning system the state that is under
development is displayed on a television monitor in the background, during a
news conference Thursday, Sept. 29, 2016, in Rancho Cordova, Gov. Jerry Brown
has signed legislation to develop a statewide earthquake early warning system
in California, after devoting $10 million to the program in the state budget he
signed this year. AP Photo/Rich Pedroncelli
Gov. Jerry Brown signed legislation Thursday that will put
California on track for a long-awaited earthquake early warning system that
officials said could begin in some areas in as little as one year.
The warning signals, delivered to smartphones and other
media, can be programmed to stop trains, halt traffic from entering tunnels,
shut down manufacturing machinery, put electronic systems in “safe” mode, and
command fire station garage doors to open. Medical procedures and other
delicate work can halt when warnings are issued.
The challenges are to link sensors and communication systems
throughout the state and deliver reliable, nearly instant warnings that may be
only a few seconds when where the quake’s epicenter is nearby.
The sensors can detect the fastest shock waves from
earthquakes, known as P-waves. Technology exists to translate the P-wave
information into predicting how much energy the earthquake will generate
moments later.
Officials said Thursday that warnings could eventually go up
to minutes for large-magnitude quakes, but little can be done for those unlucky
enough to be on top of an epicenter.
There are beta testing systems in place — the system known
as ShakeAlert, and the Bay Area Rapid Transit commuter train system has a
working earthquake warning system in place.
A 20-second warning can let a BART train slow from 70 mph to
about 10 mph, said John McPartland, a member of BART’s board of directors.
When finalized throughout the state over the next several
years, ShakeAlert will be able to send warnings over various media.
“Think of the possibilities,” said Sen. Jerry Hill during a
news conference Thursday at the California Office of Emergency Services in
Mather.
Hill, a San Mateo Democrat, is the co-author of the bill
signed by Brown, SB 438. It gives the OES authority to form an advisory board
to oversee the project, which could take years to come online for some areas.
It is a system still under development.
“We are not going to turn a key tomorrow and you are going
to get early warnings,” OES director Mark Ghilarducci said Thursday at a news
conference following the governor’s signing of SB 438.
The system should be able to detect an earthquake as soon as
possible and tell the difference between a large earthquake and a small one,
and whether an alert is warranted, said Doug Given, earthquake early warning
coordinator for the U.S. Geological Survey.
“The system can do that now in about four seconds or so; it
depends on station density,” said Givens, referring to locations of sensors.
“In general terms ... you will get somewhere from no
warning, in the worst case, to seconds to tens of seconds and in the case of
very large earthquakes, like an extremely large southern San Andreas (fault)
... minutes of warning is actually possible,” he said.
In addition to establishing an OES board to oversee
development of the warning system, SB 438 allows state general fund money to be
used for the project.
A legislative analysis estimated capital costs of $28
million to establish the system, with ongoing costs of $17 million beginning
next fiscal year to operate and maintain the system. Costs from the general
fund could be mitigated by monies from other sources, the analysis noted.
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