Analysis of Deformation Characteristic and Uplift Mechanism in Longgang Volcanoes,Jilin

Longgang Volcanoes of Quaternary is active with potential eruption risk. Three-dimensional crustal movement of the region was studied through GNSS and leveling data. The horizontal motions of the GNSS stations are within 10mm/a in SE direction, with respect to the Eurasian plate. The movement of the stations located the east of Dunhua – Mishan fault has been strongly affected by the 3·11 earthquake, 2011 in Japan. The fault is mainly extensional now. Leveling data in recent years reveal that the vertical motion is mainly uplift. The uplift is concentrated in Jingyu by InSAR during 2014—2019. The deep electrical structure is obtained based on the magnetotelluric profile. The results show the high resistivity structures of different depths are distributed in the crust of Longgang Volcanoes and its adjacent area. The high resistivity structures in the western are above 18 km. The depth in Jinlongdingzi volcano is the shallowest. The depth in the middle region is above 40 km where the early volcanoes distributed. The structures in the eastern around FuSong are above 20 km. They are speculated to be related to the consolidation of magma. The different resistivity of the structures can tell the two sides of the faults. The large-scale low resistance structure below the high resistance is supposed the magma system in the middle and lower crust. The youngest volcano, Jinlongjingzi has low resistance structure below 10 km, which is speculated a magma channel which connected to the magma system of the deep. The average depth of the east magma is relatively shallow with 30 km or so. The upwelling of the mantle material and intermittent upward migration in the region may cause the uplift and earthquakes in the crust.