碩士 / 國立中央大學 / 水文所 / 96 / Almost all devastating tsunamis were triggered by shallow earthquakes in sub-duction zones. We thus focus on the Manila sub-duction zone (or called Manila Trench), deemed as the most likely source region within the South China Sea (SCS), to assess the potential tsunami hazards in Taiwan.
To cope with the changing strikes, we group the entire Manila Trench into six hypothetical fault segments, similar to those of Kirby (2006). The width and dislocation of each fault are then inferred from its length, according to the empirical relations of Papazachos et al. (2004). In addition, by summing all the six fault segments, we create a hypothetical 990 km long fault along the Manila Trench, whose width, dislocation and focal depth are determined based on the data of the three largest earthquakes occurred in the past one hundred year .
Upon simulation of tsunami caused by earthquakes on hypothetical faults, results indicate that the heights of tsunami waves decreases as they propagate from the source region into South China Sea (SCS). However, a 60% amplification of wave height is observed along the southeast China offshore when the wave crossing the continental slope and shelf. For the 990 km long fault scenario, the tsunami wave height reaches about 5 m in southern Taiwan, Suao, and Ilan. It reaches about 10 m in southeast China and Vietnam. For the island nearest to the source region, Luzon island, the tsunami wave height can reach as high as 15 m. Simulation results of the worse case scenario also indicate that tsunami waves will arrive at the Luzon island 10 min after the earthquake and the southern Taiwan 20 min after. The more than 20min evacuation time for other regions suggests that the establishment of an effective tsunamis warning system is plausible.
We also compare the simulation results of the 990 km long fault with the tsunami of the 2004 Sumatra earthquake. The epicenter distances from Sumatra to Sri Lanka and India are comparable to those from Manila to Vietnam. As the results, we deduce comparable tsunami arrival times and wave heights along Sri Lanka, India, and Vietnam. However, while the tsunami waves can propagate further into the open Indian Ocean for the Sumatra case, the relative closeness of SCS tends to trap tsunami waves, causing more damages for Manila case.
Manila results of this study suggest that the establishment of SCS tsunami warning system is worthwhile and earthquakes in Manila sub-duction zone need to put into highly alert.
| Identifer | oai:union.ndltd.org:TW/096NCU05761005 |
| Date | January 2008 |
| Creators | Huei-Jyuan Huang, 黃惠絹 |
| Contributors | Tso-Ren Wu, Wu-Ting Tsai, Po-Fei Chen, 吳祚任, 蔡武廷, 陳伯飛 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 124 |
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