Crustal structure in the Tengchong Volcanic Area based on the H-κ-c method

The Tengchong volcano is the most famous active intraplate volcano in Southwest China, which has been dormant for hundreds. The significant seismicity, active geothermal activities and gas emissions are all indicate that the volcanoes still have potential for future eruptions. However, the origin of the Tengchong volcano is still on debate, which is strongly depend on the structure underneath. Here we employ a recently developed H-κ-c method to characterize the crustal structure with its thickness and the Vp/Vs ratio of the Tengchong volcanic area. A total of 4,040 receiver functions are obtained from 9 permanent seismic stations, providing an overall good coverage in both distance and azimuth of the analyzed data. After removing the back azimuthal effects of dipping Moho and/or crustal anisotropy, our results are more robust and highlight local variations. The crustal thickness increases from south to north, ranging from 33.5 to 41.9 km with an average of 37.6 km. The crustal thickness beneath stations RHT is thicker than the surrounding stations, suggesting a possible local crustal depression beneath this station. The Vp/Vs ratios vary from 1.75 to 1.79 and the average value is 1.76 with a standard deviation of 0.015. Stations with high Vp/Vs values indicate partial melting magma chambers in the crust beneath those stations.