[S-VC32] 活動的火山

[SVC32-P28] Seismic evidence for eruptible magma beneath the Tatun volcano group of northern Taiwan

*CHENG-HORNG LIN^1,2,3、Min-Hung Shih^2,3、Ya-Chuan 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)

キーワード：Magma reservoir, Tatun volcano group, Seismic reflections, Formosa Array

The Tatun Volcano Group (TVG) is located at the northern tip of Taiwan, adjacent to the Taipei metropolitan area. While a magma reservoir has been identified beneath the TVG, it remains uncertain whether it contains eruptible magma. By carefully analyzing reliable seismic data recorded by the Formosa Array, we identified strong seismic reflections from the roof of the magma reservoir, triggered by two extremely shallow earthquakes in the TVG. Seismic ray-tracing of these reflections indicates that the top of the magma reservoir lies at a depth of approximately 13 km, which is significantly deeper than the ~8 km depth previously estimated through seismic tomography. This distinct discrepancy provides insight into a conceptual model of magma reservoirs, suggesting a division between eruptible and non-eruptible portions. Based on our findings, we conclude that a considerable amount of eruptible magma may exist beneath the TVG. However, a volcanic eruption would only occur if the pressure from accumulating magma exceeds the rock load of the overlying crust.