Unveiling Tatun volcanic plumbing structure induced by post-collisional extension of Taiwan mountain belt

Hsin-Hua Huang,J Y.-T Ko,I Koulakov,C.-H Lin,E.-S Wu,M.-H Shih

doi:10.1038/s41598-021-84763-z

Abstract

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.

Highlights

The Tatun Volcanic Group (TVG) is proximal to the metropolis of Taipei City and has long been a major concern due to the potential risks from volcanic activity to the population and critical infrastructure
The seismic analysis of S-wave shadows and P-wave delays from deep subduction earthquakes suggested the existence of a magma reservoir in the lower crust slightly to the east of the TVG18
The new model unveils a clear magma reservoir beneath the east of the Tatun volcano group (TVG) and possible magmatic intrusion/underplating bodies related to post-collisional extension in northern Taiwan

Summary

Introduction

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. Enhanced tomographic images 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. The seismic analysis of S-wave shadows and P-wave delays from deep subduction earthquakes suggested the existence of a magma reservoir in the lower crust slightly to the east of the TVG18. The new model unveils a clear magma reservoir beneath the east of the TVG and possible magmatic intrusion/underplating bodies related to post-collisional extension in northern Taiwan

Results

Discussion

Conclusion