Single Channel Seismic Event Detection
Abstract
Several types of seismic signal detectors have been tested on NORSAR and Pinedale, Wyoming signals buried every ten minutes in approximately 22 hours of phase-scrambled noise. All plausible detectors including human analysts operate within 0.1 mb of the mean value including the present on-line 'IBM' STA/ LTA detector, a 'Z' detector, detectors with fixed or optimum filters, a 'deflection' detector, the MARS detector, a detector which cascades a recursive digital filter with Walsh transforms, and human analysts viewing unfiltered Calcomp plots. The best detector was a log-Z transform aided by a recursively updated optimum sq(S/N) filter. Among the worst were human analysts when operating in the 'pick everything' mode, the deflection detector, and a prediction-error type detector. The human analyst could, however, improve to be nearly the best if sufficient care was taken. With a modest amount of care, any detector can be modified to perform well as an element of an operational system and the choice of single channel detector can be made on other grounds than pure detection such as availability or computation speed. In this report also we outline the features of the existing on-line detector at the SDAC which, in addition to pure detection, also classifies events as spikes, drop-outs, regionals, and teleseisms and calculates a refined start time.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 07, 1981
- Accession Number
- ADA105469
Entities
People
- David Racine
- Raleigh Romine
- Robert R. Blandford