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Dynamics of Magmatic Processes and Subsurface Structures Unveiled: A Geophysical Study in the Hainan volcanic field

Xiangyu Sun1, Yan Zhan1, Yongwei Zhao2, Guoze Zhao1, Lingqiang Zhao3, Jiandong Xu2, Jiuchang Hu4, Bin Zhou5, Ni Li2, Xiaojuan Xiang4, Chongtao Hao1, Yuxin Bao6

  • Affiliations: 1State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing, China；2National Observation and Research Station of Jilin Changbaishan Volcano, Antu, Key Laboratory of Seismic and Volcanic Hazards, Institute of Geology, China Earthquake Administration, Beijing, China； 3Second Monitoring and Application Center, China Earthquake Administration, Xi\'an, China； 4Earthquake administration of Hainan Province, Haikou, China；5Earthquake Agency of Guangxi Zhuang Autonomous Region, Nanning, China6Guangdong Earthquake Agency, Guangzhou, China

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 168

  • Programme No: 3.5.27

  • Theme 3 > Session 5

Abstract

The Hainan volcanic field (HNVF) is one of China's most active Holocene volcanic areas. Due to a lack of comprehensive geophysical research, questions persist regarding the deep magma system structure of the HNVF. For example, it is unclear whether the intense seismic activity in its eastern part may be a precursor to renewed volcanic activity. We present new three-dimensional electrical conductivity images, derived from magnetotelluric data, that provide a new understanding of the deep magma system in the HNVF. Our results reveal the presence of multiple sets of low-resistivity structures in both shallow (<5 km) and deep (5~25 km) regions. Although once associated with past volcanic activity, a widespread shallow low-resistivity layer on the northwest side of the HNVF is not currently indicative of shallow magma chambers. Instead, a large-volume low-resistivity structures in the western part of the HNVF may represent the current crustal magmatic plumbing system. Our analysis suggests that the intense seismic activity in localized areas of the crust lacks corresponding low-resistivity structures, which indicates that there is no direct correlation between seismicity and movement of magma. Recent volcanic eruptions in the HNVF are primarily concentrated near the Changliu-Xiangou fault, which may indicate that the migration of magma in the HNVF has utilized crustal weak zones.