碩士 / 國立臺灣海洋大學 / 地球科學研究所 / 106 / In June of 2016, 9 ocean-bottom seismometers (OBSs) of Taiwan (5 km interval) and 3 OBSs of Fujian (15 km interval) were deployed and recovered along HX08 profile from the Taiwan Shoal to the Littoral Faulted Zone in the southern Taiwan Strait. Firstly, the travel time of the refracted and reflected waves were picked from OBS data. Subsequently, the P-wave velocity model was inverted by using the travel times of the refracted and reflected waves with a travel-time error of each phase from each OBS data less than 0.1s. From the P-wave velocity model along HX08, the sediments were thickening southeastward (0.8-3 km) with the P-wave velocity of 1.6-4.5 km/s. Furthermore, large variations of the P-wave velocities (4.6-6.0 km/s) in the upper crust, interpreted as faults, at both sides of the Cenozoic Depression across the southern Taiwan Strait were caused by flexural bending to form the graben and the horst. Moreover, the middle crust below the Cenozoic Depression bent upward, which may be associated with an earthquake with a magnitude of 6 occurred on 23 November, 1878. We suggest that crustal structures in the southern Taiwan Strait were one part of the foreland-basin system to induce the faults and earthquakes. On the other hand, we also inverted the P-wave velocity models along MGL0906-01 (4 OBSs) and MGL0906-04 (5 OBSs and 11 Land Stations) seismic lines which belong to the 2009 TAIGER project, and integrated two seismic lines (HX07, HX08) in the southern Taiwan Strait to establish a pseudo-3D crustal structure. We suggest that the Moho uplift (27 km) in the southern Taiwan Strait may be related to the rifting during the opening of the South China Sea, and the rifting caused the crustal stretching and thinning. Furthermore, the mantle was filled upward. We also think that the Moho uplift (23 km) off southwest Taiwan may be caused by the upward convection of the asthenosphere during the opening of the South China Sea. The integrated models along the HX08 to the MGL0906-04 indicated that the Tainan Basin is a foreland basin. The Taiwan Shoal, the Taiwan Strait Cenozoic depressions and the Dongshan uplifts all belong to the forebulge of the foreland basin system. Therefore, we infer that complex structures in the crust are potential for future earthquakes in the Taiwan Strait.
| Identifer | oai:union.ndltd.org:TW/106NTOU5135006 |
| Date | January 2018 |
| Creators | Cheng, Yu-Hsuan, 程瑀軒 |
| Contributors | Wang, Tan-Kin, 王天楷 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 74 |
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