Huang Hsin-Hua, Wu E-S, Lin C-H, Ko J Y-T, Shih M-H, Koulakov I
Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan.
Institute of Oceanography, National Taiwan University, Taipei, Taiwan.
Sci Rep. 2021 Mar 5;11(1):5286. doi: 10.1038/s41598-021-84763-z.
The Tatun Volcanic Group (TVG) is proximal to the metropolis of Taipei City (population of ca. 7 million) and has long been a major concern due to the potential risks from volcanic activity to the population and critical infrastructure. While the TVG has been previously considered a dormant or extinct volcano, recent evidence suggests a much younger age of the last eruption event (~ 6000 years) and possible existence of a magma reservoir beneath the TVG. However, the location, dimension, and detailed geometry of the magma reservoir and plumbing system remains largely unknown. To examine the TVG volcanic plumbing structure in detail, the local P-wave travel time data and the teleseismic waveform data from a new island-wide Formosa Array Project are combined for a 3D tomographic joint inversion. The new model reveals a magma reservoir with a notable P-wave velocity reduction of 19% (ca. ~ 19% melt fraction) at 8-20 km beneath eastern TVG and with possible northward extension to a shallower depth near where active submarine volcanoes that have been detected. Enhanced tomographic images also reveal sporadic magmatic intrusion/underplating in the lower crust of Husehshan Range and northern Taiwan. These findings suggest an active volcanic plumbing system induced by post-collisional extension associated with the collapse of the orogen.
大屯火山群（TVG）紧邻台北市（人口约700万），长期以来一直是人们主要关注的对象，因为火山活动可能对人口和关键基础设施构成风险。虽然大屯火山群以前被认为是一座休眠或死火山，但最近的证据表明，上次火山喷发事件的时间要年轻得多（约6000年），而且大屯火山群下方可能存在岩浆库。然而，岩浆库和管道系统的位置、尺寸和详细几何形状在很大程度上仍然未知。为了详细研究大屯火山群的火山管道结构，将来自新的全岛式福尔摩沙阵列项目的本地P波走时数据和远震波形数据结合起来进行三维层析联合反演。新模型揭示了一个岩浆库，在大屯火山群东部下方8 - 20公里处，P波速度显著降低了19%（熔体分数约为19%），并且可能向北延伸至较浅深度，靠近已探测到的活跃海底火山所在位置。增强的层析图像还揭示了湖山山脉和台湾北部下地壳中零星的岩浆侵入/底侵现象。这些发现表明，与造山带坍塌相关的碰撞后伸展作用引发了一个活跃的火山管道系统。
