Abstract
AbstractThe Taiwan orogenic belt is formed by the strong convergence between the Philippine Sea Plate and the Eurasian Plate. The detailed mountain building process is still under debated largely due to the poor constraint of deep crustal structures, particularly the geometry at the Moho-depth. Here the Moho-refracted P waves are identified from the seismic data recorded by a dense seismic array (Formosa Array) in northern Taiwan. Although the refracted seismic energy is often weak at each individual station, the waveform similarity recorded at the nearby stations provides a reliable constraint for estimating the apparent velocity recorded by the dense seismic array. The forward modeling of the observed Moho-refracted P waves shows a larger crustal thickness (~ 52 km) beneath the Backbone Ranges than beneath the adjacent Hsuehshan Ranges (~ 36 km). Such a result is not only confirming the Moho variations along a few of the NW-SE profiles from the previous studies, but also showing the strong Moho variation is well extended along the NE-SW direction. The large change in the crustal thickness across the Taiwan orogeny strongly indicate that the orogenic deformation in Taiwan might extend beyond the shallow crust, possibly involving in the deep crust and upper mantle. The Taiwan orogeny may not be reaching to the isostatic equilibrium yet.
Funder
Ministry of Science and Technology, Taiwan
Publisher
Springer Science and Business Media LLC
Subject
Earth and Planetary Sciences (miscellaneous),Atmospheric Science,Oceanography
Reference52 articles.
1. Berg JW, Long LT (1966) Characteristics of refracted arrivals of seismic waves. J Geophy Res 71:2583–2589
2. Bonilla MG (1975) A review of recent active faults in Taiwan, United States Geological Survey Open File Report, 75–41, 58 pp
3. Chemenda AI, Yang RK, Hsieh CH, Groholsky AL (1997) Evolutionary model for the Taiwan collision based on physical modelling. Tectonophysics 274:253–274. https://doi.org/10.1016/S0040-1951(97)00025-5
4. Chen YL (1995). Three-dimensional velocity structure and kinematic analysis in the Taiwan area, PhD thesis, National Central University, Jungli, Taiwan
5. Chen YL, Shin TC (1998) Study on the earthquake location of 3-D velocity structure in the Taiwan area. Meteorol Bull 42:135–169