[S-VC29] 火山の監視と活動評価

[SVC29-P02] Significantly seismic swarms after increasing seismic velocities within seismic conduit at Tatun volcano group of Taiwan

*Cheng-Horng Lin^1,2,3、Hsin-Chieh Pu⁴、Min-Hung Shih^2,3、Ya-chaun Lai^2,3 (1.Institute of Earth Sciences, Academia Sinica, Taiwan、2.National Center for Research on Earthquake Engineering, National Applied Research Laboratories, Taiwan、3.Taiwan Volcano Observatory at Tatun, Taiwan、4.Central Weather Administration, Taiwan)

キーワード：Taun volcano group, 4D seismic tomography, seismic swarm, Seismic velocity

The Tatun volcano group (TVG) is located at the northern tip of Taiwan. Although the TVG was believed extinct in the past, the late observations show it may be still active. The most important evidence among the late observations includes the dating result of some volcanic ashes as well as the seismic detection of magma reservoir. Recently, it is interesting to note that the seismic activities have been significantly increasing in 2019. To examine the possible temporal changes of crustal structures beneath the TVG, we have employed a 4D seismic tomographic method for analyzing the abundant seismic data recorded at the TVG during the period between 2014 and 2021. We have carefully selected the non-redundant earthquake data from each year for obtaining the reliable tomographic images. The results show dramatically seismic swarms in 2019 often occur in the areas where seismic velocities are increasing within a seismicity conduit, which might be associated with the ascending of deeper volcanic fluids. Thus, possible warning of seismic swarms or volcanic activity might be issued by the careful examination of temporal velocity variations in the volcanic area.