碩士 / 國立中央大學 / 地球物理研究所 / 97 / Taiwan is prone to the risk of nearfield tsunamis because of the high seismic activities in the region. The Tsunami Warning System of Central Weather Bureau (CWB) currently only predicts arrival times of such tsunami events to existing tidal stations. The objective of this study is expanding the predicting information to include tsunami waveforms and maximum amplitudes of tidal stations. We fulfill this goal by building a database of tsunami waveforms which are simulated from the propagation of unit tsunamis.
We ignore the run-up process and the approaching tsunami waves is governed by the linear shallow water wave equations. Accordingly, the tsunami waveforms can be expressed as a linear combination of unit tsunamis. In this study, the unit tsunami source is represented by a square box of 0.25° in dimension and 1 meter high seafloor displacement. We scan over the region bounded by 18°N, 27°N, 118°E, and 125°E to simulate the propagations of unit tsunamis of all box sources by COMCOT program. The thus calculated tsunami waves of unit tsunamis for existing tidal stations are stored in database. When a tsunami earthquake occurs in the Taiwan region, we will receive the earthquake location and magnitude from Taiwan Rapid Earthquake Information Release System (TREIRS) of the CWB. By Scaling Law, the fault length, width and average slip can be inferred from the magnitude. With empirical focal mechanism, the coefficients of unit tsunamis for each source box are derived and used to synthesize the tsunami waves of the earthquake for certain tidal stations. Merits of this approach are two folds. (1) By calculating the time consuming part of wave propagation in advance, the warning system is able to do rapid forecasting for nearfield tsunamis. (2) By determining the coefficients on an event by event basis, the system is flexible to cover all scenario earthquakes with a reasonable size of database.
| Identifer | oai:union.ndltd.org:TW/097NCU05134026 |
| Date | January 2009 |
| Creators | Po-Yu Lin, 林柏佑 |
| Contributors | Po-fei Chen, 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 | 61 |
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