Abstract
Traveltime-based location methods are ineffective for locating regional
seismic events which are recorded by few stations; however, the Comprehensive
Test Ban Treaty (CTBT) makes it imperative that we monitor sparsely
observed events. This paper reviews the current status of single-station
location (SSL) methods - the location of seismic events using records
from one three-component broadband digital station. We argue here
that SSL methods may ultimately provide the most effective and economical
means for monitoring small-magnitude (M\~3) seismic events over
most of the earth. Potentially, station-event distance and focal
depth may be determined accurately by utilizing broadband three-component
data and matching observed and synthetic waveforms; station-event
azimuth is determinable from the polarization of the P-wave arrival
and P coda. However, more research is required before SSL methods
become a practical alternative to traveltime-based methods. Currently,
the most significant problem is that regional seismograms are strongly
dependent on regional crustal structure. Thus, future research efforts
should focus both on determining appropriate crustal models in specific
regions, and also on improved methods for dealing with regional variations
in crustal structure. A second important problem concerns location
errors; with SSL they may involve 180 deg errors in station-event
azimuth or other highly non-Gaussian 'blunders'.
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