ShakeAlert Not Just a
October 18, 2018
Coast's earthquake early warning system is still under construction but
is available for public use
Government officials and Caltech scientists gathered at the Caltech
Seismological Laboratory on October 17 to declare ShakeAlert—an
earthquake early warning system for the three states along the West
Coast—"open for business."
Caltech president Thomas Rosenbaum, Sonja and William Davidow
Presidential Chair and professor of physics, led the midmorning press
conference, which included U.S. Representative Adam Schiff; U.S.
Representative Judy Chu; Tom Heaton, professor of engineering
seismology; Lucy Jones, research associate in geophysics at Caltech and
founder of the Dr. Lucy Jones Center for Science and Society; Doug
Given, earthquake early warning coordinator for the United States
Geological Survey (USGS); and Ryan Arba, seismic hazards branch chief at
the California Office of Emergency Services.
"Caltech has worked for nearly 100 years with colleagues in government
and other academic institutions to leverage the insights and tools of
seismology against the risks of earthquakes," Rosenbaum said, announcing
a new stage in the development of an earthquake early warning system for
the West Coast. "Partner institutions can now use ShakeAlert to
automatically slow trains; warn industrial sites to shut off gas lines;
and warn personnel to drop, cover, and hold on."
Given added: "Today is important because we're making a large change
from a production prototype in pilot mode to an open-for-business
operational mode. Now, the system is not yet finished, it's not yet
complete; there is a lot of work to be done. However, there is a lot of
capability in the system as it exists today to the point that it can
definitely be used."
Earthquake early warning systems like ShakeAlert consist of a network of
sensors near faults that transmit signals to data-processing centers
when shaking occurs. These data-processing centers use algorithms to
rapidly determine the earthquake's location, magnitude, and the fault
rupture length—determining the intensity of an earthquake and sending
out an alert that can provide seconds or even minutes of warning. Paired
with automated responses that will shut off gas before shaking starts,
ShakeAlert could be instrumental in preventing the fires that typically
damage cities after a major earthquake, Jones said.
Earthquake early warning systems do not predict earthquakes before they
happen. Rather, they transmit a heads-up that an earthquake is
happening; a heads-up that can arrive ahead of the seismic waves
generated in the quake, potentially providing crucial time to allow
individuals to take cover and for infrastructure to prepare for the
quake (for example, for trains to halt operation). These warnings
operate on the principle that seismic waves travel at just a few miles
per second, but messages can be transmitted almost instantly. During an
earthquake, several types of seismic waves radiate out from the quake's
epicenter, including compressional waves (or P-waves), transverse waves
(or S-waves), and surface waves. The weak P-waves move faster than the
damaging S-waves and surface waves. With an earthquake early warning
system in place, those P-waves will trigger sensors that can send out a
warning ahead of the arrival of the S-waves and surface waves.
Though only half of the sensor network that ShakeAlert will need has
been built out so far—primarily around major metropolitan areas—the
state of California and the federal government have allocated funding
that should allow the rest of California's portion of the network to be
constructed over the next two years, Given said. In addition, an upgrade
to the software that processes data from the sensor networks was
deployed on September 28. This new software should reduce the number of
mistakes and missed alerts, making ShakeAlert more reliable, Given said.
A key step now is for companies and institutions to help find ways to
take advantage of these alerts to save lives, he said.
"This is a wonderful milestone," Schiff said. "We can now see the end, I
hope, in two or three years where the system is fully built out and
funded and in operation. And once people come to see the benefit, then
the future of the system will be even brighter. Getting that kind of
advance notice is going to be so meaningful in terms of making sure
people get to a safe place."
Future iterations of the system will be able to send warnings to cell
phones as well, Schiff said. Such alerts will need to be rolled out with
public education to explain to individuals what to do when they receive
such alerts—not to panic—and know that there could be false alarms.
Chu, whose district includes Caltech, said, "One of the reasons that I
am so proud to be a representative from this area is our science. In our
district, amazing advances are happening every day that will take us to
Mars or bring us a better understanding of our environment. And the
ShakeAlert that we are announcing today belongs in that pantheon of
history-making innovations to come out of Caltech."
For Heaton, one of the fathers of ShakeAlert and a scientist who has
been interested in earthquake early warning since 1979, this is a day
that was a long time in coming.
"In those days, I could see that we could technically do it. But what I
didn't really understand was what was involved to get 40 million people
on the West Coast to get together to try and make this system a reality.
What it really takes is leadership to do that," Heaton said.
Earthquake early warning systems already exist in Mexico and Japan,
which have experienced recent and devastating earthquakes. But it has
been difficult to find the political will to spend millions of dollars
developing a system for the U.S. West Coast, which is long overdue for a
ShakeAlert has been in development since 2006. In 2011, Caltech, along
with UC Berkeley and the University of Washington received $6 million
from the Gordon and Betty Moore Foundation for the research and
development of the system; and in 2015, the USGS announced approximately
$4 million in awards to Caltech, UC Berkeley, the University of
Washington, and the University of Oregon for ShakeAlert's expansion and
ShakeAlert's infrastructures consist of the California Integrated
Seismic Network (400 ground-motion sensors operated by Caltech in
partnership with UC Berkeley, the USGS, and the State of California),
and the Pacific Northwest Seismic Network (a similar regional network
operated by the USGS, University of Washington, and the University of
Over the past few years, ShakeAlert has detected thousands of
earthquakes, including two that caused damage. It began sending alerts
within four seconds of the beginning of the magnitude 5.1 La Habra
earthquake in 2014, and gave users in Berkeley five seconds of warning
before seismological waves arrived during the magnitude 6.0 South Napa
earthquake, also in 2014. Beta-test users received these alerts as a
pop-up on their computers; the pop-up displayed a map of the affected
region as well as the amount of time until shaking would begin, the
estimated magnitude of the quake, and other data.