A new seismogeodetic approach applied to GPS and accelerometer observations of the 2012 Brawley seismic swarm: Implications for earthquake early warning

TitleA new seismogeodetic approach applied to GPS and accelerometer observations of the 2012 Brawley seismic swarm: Implications for earthquake early warning
Publication TypeJournal Article
Year of Publication2013
AuthorsGeng JH, Bock Y, Melgar D, Crowell BW, Haase JS
JournalGeochemistry Geophysics Geosystems
Volume14
Pagination2124-2142
Date Published2013/07
Type of ArticleArticle
ISBN Number1525-2027
Accession NumberWOS:000323828800004
Keywords1-hz gps; broad-band; california; displacement; earthquake early warning; elarms; global positioning system; GPS geodesy; motion; network; phase ambiguity resolution; Precise point positioning; seismogeodesy; Seismology; southern; tightly coupled Kalman filter
Abstract

The 26 August 2012 Brawley seismic swarm of hundreds of events ranging from M1.4 to M5.5 in the Salton Trough, California provides a unique data set to investigate a new seismogeodetic approach that combines Global Positioning System (GPS) and accelerometer observations to estimate displacement and velocity waveforms. First in simulated real-time mode, we analyzed 1-5 Hz GPS data collected by 17 stations fully encircling the swarm zone at near-source distances up to about 40km using precise point positioning with ambiguity resolution (PPP-AR). We used a reference network of North American GPS stations well outside the region of deformation to estimate fractional-cycle biases and satellite clock parameters, which were then combined with ultrarapid orbits from the International GNSS Service to estimate positions during the Brawley seismic swarm. Next, we estimated seismogeodetic displacements and velocities from GPS phase and pseudorange observations and 100-200 Hz accelerations collected at three pairs of GPS and seismic stations in close proximity using a new tightly coupled Kalman filter approach as an extension of the PPP-AR process. We can clearly discern body waves in the velocity waveforms, including P-wave arrivals not detectable with the GPS-only approach for earthquake magnitudes as low as M-w 4.6 and significant static offsets for magnitudes as low as M-w 5.4. Our study shows that GPS networks upgraded with strong motion accelerometers can provide new information for improved understanding of the earthquake rupture process and be of critical value in creating a robust early warning system for any earthquake of societal significance.

DOI10.1002/ggge.20144
Short TitleGeochem. Geophys. Geosyst.
Student Publication: 
No