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Improved Earthquake Monitoring Using Seismic Array Data: Alexander R. Hutko   Alexander R. Hutko

Project Title: Improved Earthquake Monitoring Using Seismic Array Data
Mendenhall Fellow: Alexander R. Hutko, (303) 273-8623, ahutko@usgs.gov
Duty Station: Golden, Colorado
Start Date: March 31, 2008
Education: Ph.D. (Earth Sciences), University of California, Santa Cruz, 2008
Research Advisors: Harley Benz, (303) 273-8497, benz@usgs.gov; Paul Earle (303) 273-8417, pearle@usgs.gov; Stuart Sipkin, (303) 273-8415; David Wald, (303) 273-8441, wald@usgs.gov



Project Description:
The USGS National Earthquake Information Center (NEIC) monitors earthquakes around the world in real time. In the last few years, real time data from many small-, medium- and large-aperture seismic arrays have become available to NEIC. With the advent of new seismic arrays [for example, US Array (US) and Hi-net (Japan] come new opportunities to better (and/or more rapidly) detect and characterize earthquakes. The goal of this project is to explore recent and develop new array-based methods, which may one day be adapted for real time earthquake monitoring purposes by the NEIC.

One particularly promising array method developed in the wake of the devastating Mag 9.1 Sumatra earthquake of 2001 backprojects P-wave energy to its origin in both space and time. This can be applied to large earthquakes with fault lengths greater than ~50 km (>Mag 7.5). The figures below show images from the May 12, 2008 Sichuan earthquake in China. The results give estimates of rupture length, duration, direction and velocity without requiring any a priori information. Initial results were obtained within 2 hours of the event. This time can be reduced to a few tens of minutes if implemented into a real time monitoring environment. This method is also useful at detecting small aftershocks that sometimes escape routine detection when their signals are buried in the coda of seismic waves from the main shock. Locating aftershocks following a catastrophic earthquake is important, since they are one of the most reliable indicators of where slip (and possible damage) likely occurred.

Tracking the rupture of the Sichuan earthquake rupture by backprojecting high frequency P-wave data from 150 European broadband stations   Tracking the rupture of the Sichuan earthquake rupture by backprojecting high frequency P-wave data from 150 European broadband stations. Warm colors represent energy release from the rupture front. Small stars are aftershocks within 4 hours of the main shock (large star). From these images one can estimate rupture length (~220 km), duration (~75 sec), velocity (~2.7 km/sec) and direction (towards NE). The minimal computation time and short time window of data required to produce these images is only a few tens of minutes, making this method an attractive candidate for implementation into real time earthquake monitoring operations.

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Last modified: 16:08:29 Thu 13 Dec 2012