碩士 / 國立臺灣海洋大學 / 應用地球科學研究所 / 101 / In this study, we analyze four-component (hydrophone, vertical and two horizontal components) data recorded from 25 ocean-bottom seismometers (OBS) in 2008 for investigating converted shear waves and for estimating gas-hydrate saturation west of the Yuan-An Ridge off SW Taiwan. Firstly, initial Vp/Vs models west of the Yuan-An Ridge were constructed for P-wave velocity models based on the previous studies. Subsequently, travel time and amplitude of the P-S converted waves were synthesized based on initial Vp/Vs models and were superimposed on four-component OBS data for determining the phases of P-S converted waves. Secondly, we picked the travel times of the P-S converted waves from the four-component OBS data to invert the Vp/Vs model. Finally, we reduce the travel time errors to obtain a better Vp/Vs model. Furthermore, the gas-hydrate saturation was estimated by the four-phases four-materials (water, free gas, hydrates and rock matrix) of Wood’s equation based on the P-wave velocity (1.80-1.95 km/s) and the Vp/Vs (3.18-3.38) of gas-hydrate layer. Therefore, hydrate saturation of 5 -17% are estimated in the west sedimentary basins at the Yuan-An Ridge. Since the Vp/Vs ratio west of Yuan-An Ridge in the second sedimentary layer is higher than that in the other layers, free gas may be migrated along the thrust faults and to accumulate the hydrate below the Yuan-An Ridge.
| Identifer | oai:union.ndltd.org:TW/101NTOU5135006 |
| Date | January 2013 |
| Creators | Tzu-Yung Shih, 施姿詠 |
| Contributors | Tan K. Wang, Win-Bin Cheng, 王天楷, 鄭文彬 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 50 |
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