Study on Crustal Structures of Changbaishan-Jingpohu Volcanic Area using Receiver Functions

Abstract

We have obtained 34 receiver functions from 71 teleseismic waveforms recorded by 34 stations that were installed in Changbaishan-Jingpohu volcanic area. Through inversing receiver function of 34 seismic stations, we obtain S wave velocity structures beneath the stations. The results revealed that the Moho depth is about 32-33km along Shenyang-Dunhua direction and becomes deeper toward its west side. In Changchun area, the Moho thickness reaches about 36km and under the crater of Changbaishan-Tianchi volcano, the depth of Moho reaches about 38km while beneath Jingpohu volcanic area, Moho depth is about 39km. Overall, the crustal thickness of studied area is thick in north and thin in south. We found an anomalous layer with obvious low Swave velocity beneath Changbaishan-Tianchi crater at about 10km depth. Beneath Jingpohu volcanic area there is also possibly a low S-wave velocity anomalous body at about 30km depth. The results show that the S-wave velocity gradients at Moho are obviously different between near crater and far apart from the crater. S-wave velocity gradient of Moho near crater is clearly smaller than that in area without volcano, which suggests that Moho structures beneath volcano are different from general Moho structures in other areas. The crust thickness on the two sides along Shenyang-Dunhua direction has a comparatively great changes and its location is almost the same as Dunhua-Mishan fault at near surface. Therefore, Dunhua-Mishan fault is a very important geological structure zone in the studied area.