A Study on Transversal Wave Velocity Structure beneath Seismic Stations with Input of Pure S Wave

For some deep teleseisms of which the epicentral distance is about 50°, their direct S wave phases can be separated from other seismic phases. Based on the propagation matrix method, a new method to get surface synthetic seismogram from the S wave input beneath a station is proposed. The S wave data recorded by two short‐period stations in Hebei province are fitted with this method. The results show that there are two low velocity layers for S wave, which are about 13km and 24km beneath the Hongshan station, where the crustal thickness is 33.9 km. There are also two low velocity layers at depth 18km and 30km beneath the Shexian station. The high velocity interlayer of S wave between the two low velocity layers, the thinner crust and the low S wave velocity structure above the upper mantle may be related to the Xingtai earthquake of 1966. Considering the sensitivity of S wave velocity to partial fusion, we suggest that the crust S wave velocity structure can be evidence to reveal the deep background of strong earthquakes. Inaddition, waveform fitting of short‐period S wave expands the application range of waveform information on seismograms, and provides a new method for acquisition of transversal velocity structure directly beneath a station.