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Epicentral Location Based on Rayleigh Wave Empirical Green's
Functions from Ambient Seismic Noise
Anatoli Levshin (University of Colorado at Boulder), Michail Barmin (University of Colorado at Boulder), Michael
Ritzwoller (University of Colorado at Boulder)
A new method to locate the epicenter of regional seismic events is developed with strengths and limitations complementary
to existing location methods. This new technique is based on applying Empirical Green's Functions (EGFs) for Rayleigh waves
between 7 and 15 sec period that are determined by cross-correlation of ambient noise time-series recorded at pairs of seismic
receivers. The important advantage of this method, in comparison with standard procedures based on use of body wave travel times,
is that it does not employ an earth model. Rather it is based on interpolating the EGFs to arbitrary hypothetical event locations. The
method is tested by locating well known "Ground Truth" crustal events in the western US as well as locating seismic stations using
the principal of reciprocity. Data from the EarthScope/ USArray Transportable Array as well as regional networks were used for
location. In these applications, location errors average less than 1 km, but are expected to vary with event mechanism and depth.
References
Barmin, M.P., A.L. Levshin, Y. Yang, and M.H. Ritzwoller, 2010. Epicentral Location Based on Rayleigh Wave Empirical Green's Functions
from Ambient Seismic Noise. Submitted to Geophys. J. Int.
Acknowledgements: This research was supported by DoE/NNSA contract DE-AC52-09NA29326
Record section of the Composite Empirical
Green's Functions compared with the earthquake
records at 20 remote stations for Event
on in Northern California. (a) Envelope functions
of the earthquake observed at the
remote stations (red lines) are compared with
envelopes of the Composite EGFs (blue lines).
Band-pass: 7-15 sec period. Epicentral distances
and station names are indicated at left.
(b) Locations of the remote stations (blue triangles)
and the earthquake (red star).
Schema of the Crandall Canyon mine. Our location of the
event (green star) and corresponding 90% confidence ellipse.
The left yellow push-pin marks the USGS event location, and
the right push-pin is the approximate location of the mine collapse
and trapped miners.
2010 IRIS Core Programs Proposal | Volume II | Earthquake Source Studies | II-53