Multimode ambient noise double-beamforming tomography with a dense linear array: revealing accretionary wedge architecture across Central Taiwan
Journal
Geophysical Journal International
Journal Volume
239
Journal Issue
1
Start Page
467
End Page
477
ISSN
0956-540X
1365-246X
Date Issued
2024-08-06
Author(s)
Abstract
Taiwan, one of the most active orogenic belts in the world, undergoes orogenic processes that can be elucidated by the doubly vergent wedge model, explaining the extensive island-wide geological deformation. To provide a clearer depiction of its cross-island orogenic architecture, we apply ambient noise tomography across an east–west linear seismic array in central Taiwan, constructing the first high-resolution 2-D shear velocity model of the upper crust in the region. We observe robust fundamental- and higher-mode Rayleigh waves, with the latter being mainly present in the western Coastal Plain. We develop a multimode double-beamforming method to determine local phase velocities across the array between 2- and 5-s periods. For each location, we jointly invert all available fundamental- and higher-mode phase velocities using a Bayesian-based inversion method to obtain a 1-D model. All 1-D models are then combined to form a final 2-D model from the surface to ∼10 km depth. Our newly developed 2-D model clearly delineates major structural boundaries and fault geometries across central Taiwan, thereby corroborating the previously proposed pro-wedge and retro-wedge models while offering insight into regional seismic hazards.
Subjects
Crustal imaging
Crustal structure
Seismic interferometry
Seismic noise
Seismic tomography
Surface waves and free oscillations
Publisher
Oxford University Press (OUP)
Type
journal article