关键词: 大地电磁, 电性结构, 岩浆系统, 龙岗火山

Abstract: Longgang volcano group is one of the main active volcanoes in China. Jinlongdingzi volcano, one of them, erupted on a large scale about 1600 years ago and has potential eruption risk，We used the phase tensor decomposition and two-dimensional inversion to obtain the deep electrical structure along the profile，based on the magnetotelluric profile data of a wide-band and dense sites with a length of more than 160km, which starts from Meihekou city in the West and ends at the west gate of Changbai Mountain Scenic Area in the East, passes through the core area of Longgang volcano and Jinlongdingzi volcano，The analysis shows that high resistivity structures of different depths are distributed in the crust of Longgang Volcanic Group and its adjacent area, and the high resistivity structures are deeper under the early Volcanic Group, which are speculated to be related to the consolidation of magma. There are some obvious large-scale low resistivity structures under the high resistivity structures, which are supposed to be the magmatic system of the middle and lower crust. The crustal uplift and seismic activity in the study area may be related to the magmatic activity. There may be a magma channel beneath the newly erupted Jinlongdingzi volcano (below 10km), which is connected with the magma system of the middle and lower crust, and the magma above 10km may have been consolidated. The low resistivity structures of the middle and lower crust found in the eastern part of the section shows that it continues to extend to the eastern Changbaishan Tianchi Volcanic Area. Combined with previous magnetotelluric and seismological research results, it is speculated that the Longgang Volcanic Group and the Changbaishan volcano may share a magmatic system in the middle and deep parts.

Key words: Magnetotelluric, electrical structure, magmatic system, Longgang volcano