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Seismo Lab
Earth & Planetary
UC Berkeley

E-larmS: Earthquake early warning algorithm

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E-larmS is an earthquake early warning algorithm that has been developed and implemented by the UC Berkeley Seismological Laboratory. It is a core algorithm generating the alert messages issued by ShakeAlert.

E-larmS development started in 2001, real-time testing in California began in 2007, and delivery of alerts to test users began in 2011. E-larmS is part of ShakeAlert and now provides alerts to test users in California, Oregon and Washington. E-larmS is also being tested on the real-time networks in Chile, Israel, Korea and Turkey.

Technical details about the system can be found in our publications
Press coverage of the system is on the press page

MSNBC's Rachel Maddow - Moment of Geek:
Quake warning provides extra life-saving seconds

August 25, 2014 - Rachel Maddow reports on an earthquake early warning system that helps provide a few life-saving seconds before the effects of an earthquake are felt. View on the MSNBC site

Press covereage following the alert, and subsequent calls for a public system

August 24, 2014

M6.0 South Napa Earthquake:
ShakeAlert issues warning, alert from ElarmS

The above is a video capture of the warning received at the UC Berkeley Seismological Laboratory. It shows the 5 second countdown to the beginning of shaking in Berkeley and the expected shaking intensity in Berkeley which was 4 (shown IV) on the intensity scale and described as "light" shaking. The strongest shaking in Berkeley occured 10 seconds after the alert was received.

Warning time: The amount of warning time depends on the distance of the user from the epicenter of the quake; the greater the distance, the greater the warning time. For the Napa quake Berkeley got 5 sec warning, our users in San Francisco got 8 sec warning.

User actions: Our beta-testers across the San Francisco Bay Area received the alert at the same time as the Berkeley Seismo Lab. BART has implemented an automated train-stopping system. The system activated and would have stopped trains, however, at 3:20 in the morning there were no trains running. The alert was received in the 911 center in San Francisco and the the UC Police.

Press covereage following the alert, and subsequent calls for a public system

March 28, 2014

M5.1 La Habra Earthquake:
ShakeAlert issues warning across LA, alert from ElarmS

ElarmS provided the ShakeAlert for the M5.1 La Habra quake, the M4.4 Encino quake beneath the Santa Monica mountains (March 17, 2014) and the M4.2 Westwood quake (June 2, 2014), all in the Los Angeles region.

The above video shows a press conference at Caltech follwoing the La Habra quake. During the press conference ShakeAlert issues a warning for a small aftershock that is caught on camera.

First ElarmS Users Group Meeting

The first ElarmS users workshop was held at UC Berkeley from May 5-16, 2008. Participants came from South Korea, Germany, Switzerland, Puerto Rico and Hawaii. Participants shown: Richard Allen, Holly Brown, Marta Caprio, Heon Cheol Chi, Barry Hirshorn, Harold Irizarry, Geunyoung Kim, Nina Koehler, Stuart Koyanagi, Duk Kee Lee, Se Jong Lee, Yong Cheol Park, Jung Ho Park, DongHoon Sheen.

Probabilistic warning times in the San Francisco Bay Area

Using our knowledge of future likely earthquakes in northern CA and combining it with the time required by the ElarmS methodology to provide a warning, we can estimate the range of warning times that such a system could provide.

This work is presented in Allen, Seismo. Res. Lett., 77 (3), 371-376,2006.
The e-supplement contains warning times for different regions of the Bay Area.

The deterministic nature of earthquake rupture

The predominant period, tau-p-max, of the first few seconds of the P-wave from 71 earthquakes around the world with magnitudes ranging from 3.0 to 8.3 are measured. We find that tau-p-max scales with the magnitude of the earthquake despite the fact that the rupture is not complete by the time of the measurements for all events greater than M 4.0. We interpret this observation as suggesting that earthquake rupture is deterministic.

This work is presented in Olson and Allen, Nature, 438, 212-215,2005.

The potential for earthquake early warning

Using the existing seismic network in southern California and a dataset of past earthquakes, a methodology for rapid magnitude estimation of earthquakes is developed using the frequency content of the first few seconds of the P-wave. Given the accuracy and timeliness of the earthquakes information we suggest that it would be feasible to develop a warning system in the region.

This work is presented in Allen and Kanamori, Science, 300, 786-789, 2003.


Support for the earthquake early warning efforts at UC Berkeley is provided by: