Automatic Detection and Location of Teleseismic Events with Using Usarray As a Big Antenna

Abstract:

We design an earthquake detection and location algorithm that explores coherence and characteristic behavior of teleseismic body waves recorded by a large-scale seismic network. The procedure consists of three steps. First, for every tested source location we construct a time-distance gather by computing great-circle distances to all stations of the network and aligning the signals respectively. Second, we use the constructed gather to compute a Tau-P transform. For waves emitted by teleseismic sources, the amplitude of this transform has a very characteristic behavior with maxima corresponding to different seismic phases. Relative location of these maxima on the time-slowness plane strongly depends on the distance to the earthquake. To explore this dependence, in a third step, we convolve the Tau-P amplitude with a time slowness-filter filter whose maxima are computed based on prediction of global travel-time calculator (Buland and Chapman, 1983). As a result of this three-step procedure, we obtain a function that characterizes a likelihood of occurrence of a seismic event in a given position in space and time. We test the developed algorithm by applying it to continuous vertical-component seismograms of USArray recorded during 2010.