Template matching for simple waveforms with low signal-to-noise ratio and its application to icequake detection

Template matching is a useful method to detect seismic events through waveform similarity between two signals. The traditional template matching method works well in detecting small tectonic earthquakes. However, the method has some difficulty when the signals have relatively low signal-to-noise ratios (SNRs) and simple shapes, e. g. a sinusoidal function. In this study, we modify the traditional template matching approach for this situation. We first construct a virtual three-component seismic station using vertical-component waveforms recorded by three stations. Next, we select a template event from the virtual station, and apply the traditional template matching. We then verify this method by detecting icequakes with simple waveforms on the Urumqi Glacier No. 1 and compare the results with those from the short-term-averages over long-term-average (STA/LTA), the REST method, and traditional template matching method. It can be concluded that the modified template matching method using virtual stations has some advantages for seismic data with low SNRs.