Magmatic System and Seismicity of the Arxan Volcanic Group in Northeast China

Abstract

The Arxan volcanic group is one of the largest active volcanic fields in China. Its last eruption occurred ∼2,000 years ago, but it still has a potential of eruption in the future. The spatial distribution and migration channel of its magmatic reservoirs are still unclear. Here we precisely locate microearthquakes and study the detailed 3-D velocity structure of the volcanic area using a large number of high-quality P and S wave arrival-time data recorded at 227 portable seismometers. A swarm of microearthquakes (M < 1.5) related to magmatic activity were recorded, which lasted about 4 days during 13–16 September 2020. Our tomographic results show that 12 Arxan volcanoes share the same magmatic system. The melt fraction of a magma chamber below the Tianchi volcano at ∼0–8 km depths is estimated to be ∼6.1%–8.6% from the seismic velocity reductions. Our results indicate that the Arxan magmatic system is still active at present.