3-D Distinct Element Modeling for the current crustal deformation of southwestern Taiwan
Date Issued
2006
Date
2006
Author(s)
Ho, Wan-Yun
DOI
zh-TW
Abstract
I use the GPS measurements which have been conducted by Central Geological Survey for investigating the fault surface activity and crustal deformation patterns in southwestern Taiwan. In the central study area near Chaochou Fault, GPS stations move nearly toward the west with respect to the stable continental shelf by using S01R as a reference point. In the coastal area of Pingtung Plain, the displacement vectors show a counter-clockwise deviation toward the southwestern, which we explain it in terms of lateral extrusion bounded by the major faults of study area. I also exploit the GPS data to calculate the strain rate in study area. The result of strain rate reveals a southward increasing of extension strain rate. This result infers that the lateral extrusion happen as a result of low confining boundary of accretionary prism of Manila subduction zone.
Thus, I apply 3-D distinct element model to characterize the crustal deformation in study area with kinematic boundary conditions. I construct the model with six major discontinuities such as the basal décollement the Chishan Fault, the Chaochou Fault, the Kaoping Inferred Fault, the Longitudinal Valley Fault and deformation front, respectively. The northwestern boundary located on the Peikang High and the continental shelf is considered as fixed. The basal boundary condition is also fixed. The eastern boundary is assigned as the plate motion between the Philippine Sea plate and Eurasia with a velocity of 7 cm/yr toward N50°W. I assign another eastern boundary condition that I take the eastern boundary as the Central Ridge with a velocity of 4.6 cm/yr toward N76°W. The preliminary result of predicted velocity field of this model can reveal similar deformation pattern as shown by the GPS data. But the result of predicted velocity field in the coastal area of the Kaoping Plain has larger residual than that of other area. The result of model can also support the activity of the Chishan Fault.
Subjects
構造逃脫
三維個別元素法
基底滑脫面
旗山斷層
tectonic extrusion
3-D distinct element method
southwestern Taiwan
basal dé
collement
the Chishan Fault
3DEC
Type
thesis
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