RAYLEIGH WAVES FROM HIGH GAIN LONG-PERIOD STATIONS: SIGNAL EXTRACTION;AMPLITUDE DETERMINATION;AND SEPARATION OF OVERLAPPING WAVE TRAINS

摘要

Rayleigh waves are extracted and amplitudes (with standard errors) and origin time (within a few seconds) determined by use of reference earthquakes or explosions, high pass (HP) and normalized matched (NM) (or correlation) filters, and the oceanic group-velocity dispersion between 38 and 18 seconds. For a signal-to-noise ratio between 0.2 and 0.1 on the original single-component records, amplitudes for Rayleigh waves over oceanic paths of 155 degrees at station MAT and 98 degrees at station KIP have been determined as 12 m(mu) (10 digital units) and 24 m(mu) (25 digital units) peak-to-peak (p-p), respectively, with a standard error of less than 11%. In each case the processed signal is the highest in a half-hour processed record. The method also provides high resolution of co-located events with short time separation, or widely spaced events with Rayleigh waves arriving nearly simultaneously at a single station.