碩士 / 國立中央大學 / 地球科學學系 / 104 / Located behind the Ryukyu islands, the offshore area of the northeast Taiwan is subjected to the extension of the Okinawa Trough back-arc basin, Normal faults, submarine volcanoes and gas seeps are distributed in the trough, indicating the south Okinawa Trough is very active. Considering the dense population in northern Taiwan, the coastal area of northern Taiwan is under menace of natural hazards from potential large earthquakes and tsunamis. To better understand the seabed features and the potential submarine landslides off northern Taiwan, we have conducted and analyzed marine geophysical surveys off NE Taiwan.
In the Keelung Shelf, the seafloor edifices are generally NE-SW trending. The NE-SW orientation is coherent with the trend of the Taiwan mountain belt and perpendicular to the convergent direction of the Philippine Sea Plate relative to the Eurasian Plate. Observed in the Keelung Shelf, the normal faults are due to the back-arc extension. However, structural folds exist in the deeper strata. We suggest that the folds could be the inherited from the early Taiwan orogeny. Using scientific echo sounder, we have found 18 gas flares near the Turtle Island and 21 gas flares around the Mein-Hua Submarine Canyon. Those flare could be related to the back-arc volcanism. The flares near the Mein-Hua Submarine Canyon could be also related to a strike-slip faulting, facilitating the upward migration of the volcanic gas. The continental slope is general about 5° ~ 10° of the Keelung Shelf; however, some slope could be reach 25° ~ 30° at some internal gullies or canyons. Submarine landslides are located at steeper gradient. We suggest that there are four potential submarine landslide areas located at the continental slope of water depth 200 ~ 400 meters. The total volume of potential submarine landslides could be 18 cubic kilometers.
| Identifer | oai:union.ndltd.org:TW/104NCU05134012 |
| Date | January 2016 |
| Creators | Chi-Lo Huang, 黃琪洛 |
| Contributors | Shu-Kun Hsu, 許樹坤 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 125 |
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