WARNING CALIFORNIA: DEVELOPMENT OF A STATEWIDE ADVANCED EARTHQUAKE ALERT PROTOTYPE

The California Integrated Seismic Network has been testing realtimealgorithms designed to provide advanced alerts up to tens of seconds prior to ground shaking, i.e. earthquake warnings. The development effort has now completed a three-year initial testing program during which the algorithms were implemented on the realtime seismic systems throughout the state. The test systems now run statewide, integrating data from the Northern and Southern California Seismic Networks and the Berkeley Digital Seismic Network, and they have successfully detected earthquakes and accurately predicted the peak ground shaking a few seconds before it was felt. The current systems generate various output streams that are archived by the testing center. There is currently no capability to provide warning outside the development group. The CISN is now beginning another three-year project to build a prototype alert system that will provide warnings to a small group of test users. The new system will integrate components developed and implemented over the last few years into a single warning stream. The system will make use of both single-station and network-based approaches to provide an initial rapid warning followed by updated information with increasing accuracy. Users will be able to select the required accuracy of the information they receive, recognizing that increased accuracy comes at the cost of reduced warning time.