Development of Earthquake Early Warning System in Southern California Using Real Time GPS and Seismic Data
Abstract
We discuss the fusion of low-latency (1 s) high-rate (1 Hz or greater) CGPS total displacement waveforms and traditional seismic data, in order to extend the frequency range and timeliness of surface displacement data already available at lower frequencies from space borne InSAR and (typically daily) CGPS coordinate time series. The goal of our NASA AIST project is to develop components of early warning systems for mitigation of geological hazards (direct seismic damage, tsunamis, landslides, volcanoes). The advantage of the GPS data is that it is a direct measurement of ground displacement. With seismic data, this type of measure has to be obtained by deconvolution of the instrument response and integration of the broadband (velocity) measurements, or a double integration of the strong motion (acceleration) measurements. Due to the bandwidth and the dynamic range limits of seismometers the accuracy of absolute displacements so derived is poor. This problem is not present in the high-sample rate GPS data. We have developed a multi-rate Kalman filter that can combine in real time the complementary GPS and seismic data for use in an earthquake early warning (EEW) system, which results in an improved determination of total displacement waveforms by taking advantage of the strong points of each data type. While the seismic measurement provides a powerful constraint on the much noisier GPS measurements, unlike the seismometer, the GPS receiver never clips. We have identified about 25 “co-located” real-time GPS and broadband seismic stations (STS-1, STS-2, and CMG-3T instruments) in southern California. We are currently addressing issues related to data formats and metadata exchange, which will allow us to efficiently combine the two data types in the multi-rate Kalman filter. We describe the elements of the EEW system for southern California, discuss issues of detection and characterization of signals, and consider minimization of false alarms. We show an example of the how the system works using the Mw=7.8 ShakeOut simulation in November, 2008.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.S22A..08S
- Keywords:
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- 1207 GEODESY AND GRAVITY / Transient deformation;
- 1295 GEODESY AND GRAVITY / Integrations of techniques;
- 7215 SEISMOLOGY / Earthquake source observations;
- 7294 SEISMOLOGY / Seismic instruments and networks