Cheng, Win-BinWin-BinChengLee, Chao-ShingChao-ShingLeeLiu, Char-ShineChar-ShineLiuSchnurle, PhilippePhilippeSchnurleLin, Shiao-ShanShiao-ShanLinTsai, Hong-RuaiHong-RuaiTsai2009-12-092018-06-282009-12-092018-06-282006http://ntur.lib.ntu.edu.tw//handle/246246/173967http://ntur.lib.ntu.edu.tw/bitstream/246246/173967/1/38.pdfIn the fall of 2004, four profiles of a total length of about 80 km and 24 recovered Ocean Bottom Seismometers (OBSs) were acquired along off-shore southwestern Taiwan. These profiles were oriented in E-W and N-S directions to map the velocity structure of sediments by modeling the vertical component of OBS data. The thickness of sedimentary layers ranges from a few hundred meters to about 2 km, with the largest thickness being found beneath ridges. The most striking feature in the velocity models along E-W profiles is the relatively high velocity wedges, extending from the seafloor to about 2 km in depth; these could be interpreted as a series of westward upthrust faults. The feature of relatively high P-wave velocity could be considered a result of local shallowing of the base of the gas hydrate stability zone, caused by ascending flows of deep fluids passing through the fault zone. In the N-S profiles, a dome-like high velocity structure was observed and could be associated with the phenomenon of hydrate/gas phase boundary fluctuation. After erosion, the sub-seafloor temperature gradient redistributes and results in the hydrate/gas phase boundary moving downward. The results obtained in this study show that tectonic control is an important factor in determining bottom-simulating reflector (BSR) distributions offshore of southwestern Taiwan.application/pdf7605471 bytesapplication/pdfen-USGas hydrates; Methane migration; OBS seismic data; Seismic tomography[SDGs]SDG14marine sediment; numerical model; seafloor; seismic data; seismic reflection; seismic tomography; seismometry; tectonic setting; temperature gradient; velocity structurejournal article10.3319/TAO.2006.17.4.739(GH)2-s2.0-33846932797WOS:000243814800008http://ntur.lib.ntu.edu.tw/bitstream/246246/173967/1/38.pdf