American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article (file size: 1326205 bytes)    Cited by

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. B10, 2458, doi:10.1029/2002JB002336, 2003

Surface deformation and tectonic setting of Taiwan inferred from a GPS velocity field

Annemarie G. Bos

Faculty of Earth Sciences, Utrecht University, Utrecht, Netherlands


Wim Spakman

Faculty of Earth Sciences, Utrecht University, Utrecht, Netherlands


Marleen C. J. Nyst

Delft Institute of Earth Oriented Space Research, Delft University of Technology, Delft, Netherlands


Abstract

We have determined the present-day surface deformation of Taiwan by computing the velocity gradient field and fault slip from 143 GPS velocity vectors. In southern Taiwan the derived strain and rotation rates and fault slips are indicative of lateral extrusion toward the south. In northern Taiwan we infer the onset of gravitational collapse which is induced by the on-land extension of the Okinawa Trough. In the eastern Central Range the observed inverted NW-SE extension is consistent with geological observations and high heat flow measurements. This could be the result of exhumation of crustal material. The model further shows a significant decrease in slip rate northward along the Longitudinal Valley fault at 23.7°N. The northern Coastal Range shows high strain rates and two oppositely rotating blocks. By combining the surface deformation model with seismicity data and seismic tomography we are able to propose a coherent model for the present-day tectonic activity. Both seismicity and tomography show further evidence for active, southward propagating exhumation of a crustal slice in the eastern Central Range. Offshore east Taiwan we deduce strong evidence of a southward propagating crustal tear fault, accommodating most of the Philippine Sea Plate-Eurasian Plate convergence. The tear is the crustal response to incipient northwestward subduction of the Philippine Sea Plate. Thus the Ryukyu Trench is bending southward becoming almost perpendicular to the convergence direction, while subduction of the Philippine Sea Plate continues. In this setting a sudden rapid southward propagation of the afore mentioned tear is conceivable.

Received 6 December 2002; accepted 18 June 2003; published 1 October 2003.

Index Terms: 1208 Geodesy and Gravity: Crustal movements—intraplate (8110); 8110 Tectonophysics: Continental tectonics—general (0905); 9320 Information Related to Geographic Region: Asia.

Read Full Article (file size: 1326205 bytes)    Cited by

Citation: Bos, A. G., W. Spakman, and M. C. J. Nyst (2003), Surface deformation and tectonic setting of Taiwan inferred from a GPS velocity field, J. Geophys. Res., 108(B10), 2458, doi:10.1029/2002JB002336.