Horizontal Deformation From Continuous GPS Measurements in Taipei Basin
Reporter: Chiu Chi-Yu
Abstract
Taipei Basin, located in the northern Taiwan, is filled with Quaternary siliciclastic sediments that are at least 670 m thick in the middle of the depocenter. To the east and south of the basin lie the frontal foothills of the Taiwan thrust and fold belt. The Tatun volcanic area is adjacent to the north of the basin, and the Linkou Tableland to the west of the basin consists of alluvial gravel capped by a thick laterite soil.
The Shanchiao fault, located to the west of the Taipei Basin, is an active normal fault that experienced a component of left-lateral slip and the has a length over 40 km. The fault separates the Taipei Basin and the Linkou Tableland. Due to the movement of Shanchiao fault, the depth of Tertiary basement of the Taipei Basin is at least 700 m .
With 3 years of continuous GPS data from 29 stations in the Taipei Basin and 9 long-term recording sites in Taiwan, along with other 11 IGS sites in the Asian Pacific region, we use the GAMIT/GLOBK software to calculate the coordinates and velocity of each site and obtain the time series of station positions.
Relative to a stable continental margin station, S01R, my study together with results from other recent studies of GPS velocity field in Taipei Basin show that the velocity field is about 2 ~ 5 mm/yr with a substantial NW-SE extension strain rate of about 0.1 μstrain/yr concentrated across the Shanchiao fault .
Combined with InSAR measurements from Chang et al.(2010), we observe d vertical deformation in the northern Taiwan including: (1) the slight uplift in the Western Foothills, the Tatun volcano group, and the Linkou Tableland and (2) the subsidence around the border of the Taipei Basin.References
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