California Institute of Technology

CISN ShakeAlert: Demonstration System

Scientists and engineers at the California Institute of Technology (Caltech), UC Berkeley, the Swiss Federal Institute of Technology (ETH), and the University of Southern California (USC) started in 2007 to develop and implement a prototype earthquake early warning (EEW) system for California, called CISN ShakeAlert (Böse et al., 2012). The project is funded through the US Geological Survey (USGS) that also took over the formal responsibility of earthquake alerting in California. ShakeAlert makes use of the existing infrastructure of the California Integrated Seismic Network (CISN, Caltech/UC Berkeley/USGS), including real-time waveform data streams from ~380 broadband and strong-motion stations throughout California.

CISN ShakeAlert is a distributed system, enabling the independent development of single components (Figure 1). An associator, called Decision Module, combines the outputs from three parallel implemented EEW algorithms, τc-Pd Onsite (Kanamori, 2005; Wu et al., 2007; Böse et al., 2009ab), Virtual Seismologist (Cua and Heaton, 2007; Cua et al., 2009), and ElarmS (Allen and Kanamori, 2003; Allen et al., 2007; Allen et al., 2009). Each algorithm is capable to detect and characterize earthquakes within seconds from event initiation. The earthquake alert information includes rapid estimates and uncertainties of magnitudes, locations, expected seismic intensities, and probabilities of correct alarm. A User Display that runs on a user's computer receives and displays the alert messages in real-time (Figure 2).


Richard Allen, Maren Böse, Holly Brown, Georgia Cua, Claude Felizardo, Doug Given, Egill Hauksson, Tom Heaton, Margaret Hellweg, Ivan Henson, Tom Jordan, Serdar Kuyuk, Masha Liukis, Phil Maechling, Doug Neuhauser, Margaret Vinci.

Shake Alert Decision Module

Figure 1. Scheme of CISN ShakeAlert.

Shake Alert

Figure 2. Screenshot of the User Display of CISN ShakeAlert during the 2011 M3.3 Channel Island earthquake in Southern California.


The User Display is currently being tested by around 40 scientists and engineers in California. Starting in spring 2012, we plan to expand this group to a suite of perspective users from critical industries and institutions throughout California, such as the Bay Area Rapid Transit District, to identify information necessary for ShakeAlert users, as well as delivery mechanisms, procedures, and products.

We are making the User Display available to a limited group of users as part of our testing of the EEW algorithms and software. During the testing, software modules may fail and we expect the system to be off-line some of the time. Thus, it will not be reliable and should not be used to make important decisions. We request that users do not distribute the User Display software to others, as they will not be informed about the progress of the EEW testing and/or may not understand the current limitations of the EEW prototype system. We also ask users of the prototype system not to talk to the news media or judge the system performance, because they may not have enough information to explain unexpected system performance. If EEW testing is a success, the USGS plans to raise funds to build an actual EEW system that will be available to the public, and everybody can receive alerts.

CISN ShakeAlert is a prototype EEW system that does not claim being robust enough to provide reliable and timely EEW throughout California. We estimate that a comprehensive EEW system in California would cost about $80 million over five years. A system for the entire Pacific West coast would cost approximately $150 million over five years.


General questions about CISN ShakeAlert

Richard Allen, UC Berkeley, rallen[ at ]
Tom Heaton, Caltech, heaton[ at ]

Questions about beta-testing of CISN ShakeAlert

Peggy Hellweg, UC Berkeley, peggy[ at ]
Margaret Vinci, ERA/Caltech, mvinci[ at ]