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Shakealert: Developing the Prototype Earthquake Early Warning System

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Shakealert: Developing the Prototype Earthquake Early Warning System Shakealert Developing the Earthquake Early Warning System for California California Integrated CISN Seismic Network Funded by Peggy Hellweg, Richard Allen, Maren Böse, Holly Brown, Georgia Cua, Michael Fischer, Doug Given, Egill Hauksson, Tom Heaton, Tom Jordan, Oleg Khainovski, Phil Maechling, Doug Neuhauser, David Oppenheimer, Kalpesh Solanki Swiss Seismological Service SCEC/USC What is Advanced Earthquake Alert aka Earthquake Early Warning? • rapid detection of earthquake nucleation • instant alerts of forthcoming ground shaking • updated shaking predictions as ground motion propagates • more rapid “post-earthquake” information ie ShakeMaps a continuum of earthquake information Progress toward an Advanced Earthquake Alert System for California Phase I: Development and testing of realtime algorithms Parallel statewide testing of multiple methodologies 2006-2009 – complete California Integrated Seismic Network Statewide testing CISN of three methodologies ElarmS (UC Berkeley) UC Berkeley Virtual Seismologist (Caltech/ETH) Caltech Onsite warning (Caltech/ U.S. National Taiwan University) Geological Survey the seismic networks Progress toward an Advanced Earthquake Alert System for California Phase I: Development and testing of realtime algorithms Parallel statewide testing of multiple methodologies 2006-2009 – complete Phase II: Implementation of a prototype warning system A single CISN early warning output to a group of test users Upgrade of station hardware for faster delivery 2009-20012 – started August 2009 station hardware ShakeAlert:ElarmS upgrades The CISN Virtual Seismologist Advanced Earthquake OnsiteAlert Systemwarning TODAY: outline what the warning system will look like Progress toward an Advanced Earthquake Alert System for California Phase I: Development and testing of realtime algorithms Parallel statewide testing of multiple methodologies 2006-2009 – complete Phase II: Implementation of a prototype warning system A single CISN early warning output to a group of test users Upgrade of station hardware for faster delivery 2009-20012 – started August 2009 Phase III: Public warning system Education of all users Dense geophysical networks (seismic + geodetic) statewide 201X (or after the next earthquake) Components of the new Sources of Integrated methodology information time 1st station trigger – Single station detection P-wave detection – magnitude estimate using frequency and (a few seconds) (a few – on-site ground shaking prediction amplitude information Benefits: speed Challenges: false alarms 2nd, 3rd, 4th stations trigger – Multiple station detection – event association, location, magnitude estimation – maps of predicted peak ground shaking Benefits: reduced false alarms Challenges: speed, probably not available at epicenter Additional station detections; S-wave detection S-wave detection, – update source estimates Peak shaking observations – start to map finite faults using amplitude information Benefits: improved accuracy and certainty Challenges: not available near epicenter Continuum of earthquake information – improved accuracy means reduced warning time Integrated methodology Single station detection • Trigger on P-waves; • Alarm when both amplitude and period suggest large magnitude earthquake Detections and predicted ground motions Observed ground motions example from the Onsite method Bӧse et al. 2009 Chino Hills earthquake Mw 5.4 July 28, 2008 Integrated methodology Multiple Station - Peak shaking + warning time • Trigger, magnitude from P-waves 1. Determine earthquake location 2. Estimate warning time 3. Estimate magnitude CISN ShakeMap 4. Calculate shaking intensity 5. System updates prediction continuously time with time the AlertMap evolves into a ShakeMap detection + 1 sec + 2 sec + 3 sec example from ElarmS-RT processing – Allen et al. 2009 Statewide network Heterogeneity • station density • instrumentation Dense coverage: • Bay Area: mainly accelerometers • LA area: accelerometers and broadband velocity good performance Moderate coverage: • southern CA • along San Andreas accurate but slow performance Poor coverage: • Sierra + Mendocino Triple Junction poor performance Station distribution Current seismic instrumentation 384 station sites 603 sensors 222 velocity 381 accelerometers Big Instrumentation Gaps Phase III needs to fill in gaps How quickly? Alum Rock Warning times earthquake Mw 5.4 October 30, 2007 15 sec delay CISN ShakeMap First detection (2 stations) 3rd station detection 4th station detection origin + 19 sec origin + 20 sec origin + 22 sec magnitude: n/a magnitude: 5.2 magnitude: 5.9 loc error: 13 km loc error: 4 km loc error: 4 km example from ElarmS-RT processing – Allen et al. 2009 System latency Data packetization and telemetry median: 6.5 sec CI NC NP time (sec) BK AZ ElarmS-RT latency: Seismometer to warning (on ElarmS computers) median: 11.8 sec time (sec) example from ElarmS-RT processing – Allen et al. 2009 System latency New funding during Phase II will replace most old data loggers with new (Q330s) will reduce delays by ~5 sec CI network Data will be available in ~2 sec rather that current median of 6.5 sec Time includes • data transmission • algorithm (3 sec) example from the Onsite method - Bӧse et al. 2009 • processing Warning to test user group • Will begin providing warnings to small test user group in 2010 • Currently looking for interested user groups Japanese user groups • transportation • industrial sites • schools Warnings communicated via internet and text message initially Advanced Alert Product line Earthquake intensity Strong Eq-Alert VIII motion what is the criteria? in alert Get under5 sec when do we update? 10%g in desk your area Rapid-ShakeMap ? ? currently at 1.5 min 1, 3, 5, 7, 10… peak motion observations 1, 3, 5, 7, 10… stations trigger origin time time detection + 1 sec + 2 sec + 3 sec Stream of earthquake information starts with first trigger Summary Three test systems now operational statewide in California – 600 sensors from 5 networks, 3 processing centers Accurately detecting earthquakes where there is good station coverage – Alum Rock: prediction before ground shaking in San Francisco – Chino Hills: single station detections across Los Angeles New integrated system now under construction – combines best components of test systems – station hardware is being upgraded for speed – plan to be warning test user group in 2010 Earthquake intensity Challenges/Questions VIII What are the criteria to issue an alarm? in 5 Get under sec How do we do a better job for finite faults? desk .
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