Velocity Field Derived from Taiwan Continuous GPS Array (2007 - 2013)

  • Author(s): Min-Chien Tsai, Shui-Beih Yu, Tzay-Chyn Shin, Kai-Wen Kuo, Peih-Lin Leu, Chien-Hsin Chang, and Mei-Yi Ho
  • DOI: 10.3319/TAO.2015.05.21.01(T)
  • Keywords: GPS, Time series analysis, Velocity field, Crustal deformation
Abstract

Data were collected from 281 Taiwan continuous Global Positioning System (cGPS) Array sites from 2007 - 2013 and processed with GAMIT/GLOBK software. Power spectral density stacking from cGPS position time series in Taiwan found the spectral index as -0.72, -0.77, and -0.57 for the E, N, U components, respectively. This indicates the cGPS data errors can be described as a combination of white noise and flicker noise. The common-mode errors are removed by stacking data from 50 cGPS sites with data periods greater than 5 years. By removing the common-mode errors the GPS data precision is further improved to 2.3, 1.9, and 6.9 mm in the E, N, U components, respectively. After strict data quality control, time series analysis and noise analysis, we derive a new Taiwan velocity field using cGPS data from 2007 - 2013. The general pattern of the newly derived 2007 - 2013 velocity field is quite similar to that from previous studies, but the station density is much larger and spatial coverage better. About 80 mm yr-1 plate convergence rate is observed, half of the rate is accommodated on the fold and thrust belt of western Taiwan and another half is taken up in the Longitudinal Valley and Coastal Range in eastern Taiwan. The velocities in western Taiwan generally show a fan-shaped pattern, consistent with the maximum compression tectonic stress direction. In northern Taiwan the velocity vectors reveal clockwise rotation, indicating the on-going extensional deformation related to the back-arc extension of the Okinawa Trough. In southern Taiwan, the horizontal velocity increases from about 40 mm yr-1 in the Chia-Nan area to 55 mm yr-1 in the Kao-Ping area with a counterclockwise rotation.

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