Analysis of Crustal Deformation in Taiwan Using Block Modeling with GPS Observations

• Main Authors: Chiou-Hsien Lee, 李秋賢
• Other Authors: Wu-Lung Chang
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/86402527023977674247

碩士 === 國立中央大學 === 地球科學學系 === 104 === Taiwan has been experiencing the collision between the Eurasian and the Philippine Sea Plates, therefore many active faults and abundant frequent earthquakes have been formed. In order to evaluate the earthquake potential of potentially hazardous faults, I applied amethod of block modeling to invert the horizontal velocities of 1126 GPS stations, including 285 continuous and 841 campaign stations for the long-term slip rates and slip deficit rates of 28 active faults published by the Central Geological Survey of Taiwan.To do this, I divided Taiwan into 34 blocks, with their motions referenced to the passive continental margin of the Eurasian Plate. Three models were set in this study, where the first one considers only block rotations and fault coupling effects and the second includes internal strain within the blocks. To examine the consistency between the geodetic and geological slip rates, moreover, I applied a newly published dataset of geologic fault slip rates to constrain the inversion process as the third model. The results revealed that the long-term slip rates and slip deficit rates are lower (< 3.0 mm/yr) in northern Taiwan and higherin the Western Foothills in central (8.0‐13.0 mm/yr and 7.0 mm/yr) and southern Taiwan (23.0‐27.0 mm/yr and 7.0‐10.0 mm/yr). The south part of the Longitudinal Valley fault hasa higher long-term slip rate (16.3 mm/yr) but lower slip deficit rate (0.9 mm/yr) than the north segment (11.0 mm/yr and 4.3 mm/yr), indicating the interseismic creeping behavior of south segment of the Longitudinal Valley fault. I estimated the earthquake potential from the most recent event to the next 50 years and compared to the magnitudes of characteristic earthquakes. My results infer that the earthquake with magnitude of larger than Mw 6 might occur on the faults in northern and central Taiwan. The magnitudes of the Chishan Fault and the Hengchun Fault are larger as Mw 7.5 because they are far from their recent activities. The magnitude of the north part of Longitudinal Valley (Mw 7.0) are higher than the south part (Mw 6.5).