- © 2015 by the Seismological Society of America
Rapid detection of local and regional earthquakes and issuance of fast alerts for impending shaking is considered beneficial to save lives, reduce losses, and shorten recovery times after destructive events (Allen et al., 2009). Over the last two decades, several countries have built operational earthquake early warning (EEW) systems, including Japan (Hoshiba et al., 2008), Mexico (Espinosa-Aranda et al., 1995), Romania (Mărmureanu et al., 2011), Turkey (Erdik et al., 2003), Taiwan (Hsiao et al., 2011), and China (Peng et al., 2011). Other countries, such as the United States (Böse, Allen, et al., 2013), Italy (Satriano et al., 2011), and Switzerland (Behr et al., 2015), are currently developing systems or evaluating algorithms in their seismic real-time networks.
Over the past eight years, scientists at the California Institute of Technology (Caltech), the University of California–Berkeley, the University of Southern California, the University of Washington, the U.S. Geological Survey (USGS), and the Swiss Federal Institute of Technology (ETH Zurich, Switzerland) developed the U.S. west-coast-wide ShakeAlert EEW demonstration system for California, Oregon, and Washington (Böse, Allen, et al., 2013). Real-time alerts are currently being shared with around 300 individuals, companies, and emergency response organizations to gather feedback about system performance, to educate potential end users about EEW, and to identify needs and applications of a future operational warning system.
To quickly determine earthquake magnitudes and (point-source) hypocenter locations, the Californian ShakeAlert system processes and interprets real-time waveform data streams from several hundred seismic broadband velocity and strong-motion acceleration sensors as part of the California Integrated Seismic Network (CISN). Designed as a hybrid system, ShakeAlert combines the estimates from one single-sensor and two network-based EEW algorithms that run in parallel, including τc-Pd Onsite (Wu et al., 2007; Böse, Hauksson, Solanki, Kanamori, Wu, et al., 2009; Böse, Hauksson, Solanki, Kanamori, …