HR: 1340h
AN: S43B-1299    [Abstracts]
TI: Automated Source Depth Estimation
AU: * Junek, W N
EM: wjunek@yahoo.com
AF: Air Force Technical Applications Center, 1030 S. Hwy A1A, PAFB, FL 32925-3002, United States
AU: Nieves, J R
EM: jorge@aftac.gov
AF: Air Force Technical Applications Center, 1030 S. Hwy A1A, PAFB, FL 32925-3002, United States
AU: Kemerait, R C
EM: kemerait@aftac.gov
AF: Air Force Technical Applications Center, 1030 S. Hwy A1A, PAFB, FL 32925-3002, United States
AU: Woods, M T
EM: mwoods@aftac.gov
AF: Air Force Technical Applications Center, 1030 S. Hwy A1A, PAFB, FL 32925-3002, United States
AU: Creasey, J P
EM: jon@aftac.gov
AF: Air Force Technical Applications Center, 1030 S. Hwy A1A, PAFB, FL 32925-3002, United States
AB: Source depth estimation is a key process in the discrimination of earthquakes and explosions for nuclear treaty monitoring. The lack of observable depth phases does not mean an event occurred at or near the surface. Shallow events can have closely spaced depth phases that are imperceptible to human analysts and regional events are often complicated by the simultaneous arrival of multiple phases, which makes the observation of depth phases even more problematic. We have developed an automated signal processing algorithm that estimates the depth of an event directly from the observed seismograms. It requires a series of observations of a single event by a network of seismic arrays and calculates site-specific depth phase delay times and ray parameters using cepstral processing and frequency-wavenumber analysis. These measurements are used to generate a series of depth estimates for each station in the observing network which are stacked to identify a consistent result. An iterative cepstral processing technique, and an adaptive, site specific, gamnitude threshold are used to reduce the high false alarm rate inherent to cepstral processing. A series of events having shallow free depth solutions, built from a mixture of regional and teleseismic observations, were used to test our algorithm.
DE: 7215 Earthquake source observations (1240)
DE: 7219 Seismic monitoring and test-ban treaty verification
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: 2007 Fall Meeting