碩士 / 國立臺灣大學 / 海洋研究所 / 97 / This study adopts 23 TG records from the Marine Meteorology Center of the Central Weather Bureau over several decades to estimate the magnitude of vertical crustal motion along the coast around Taiwan. There are two main targets in this study:
A. Estimating vertical crustal motion along Taiwan coast in recent decades
The tide gauge (TG) monitors the relative sea level w.r.t. the ground at the TG location, whereas satellite altimetry (ALT), for example TOPEX/Poseidon and Jason-1, measures the absolute sea level w.r.t. the terrestrial reference frame. Their difference signifies the absolute vertical ground motion for each of the available TG locations. Seasonal signals, primarily periodic tides are removed from both TG and ALT data beforehand by linear regression. We can therefore map out a whole profile of vertical crustal motion along the Taiwan coast. The majority of these motions tend to descend during the latest decade. Southwestern Taiwan shows a clear land subsidence reflecting the over withdrawal of groundwater with the largest magnitude -52.2 mm/yr in Bozihliao. The sites in the eastern Taiwan from Fugang to Hualien generally have a smaller descending rate with higher descending trend northward.
B. Re-examination of the coseismic deformation of the 1951 Hualien earthquakes
We re-examine the earthquake events occurring in Hualien downtown on Oct. 22, 1951. The mainshock was magnitude of ML 7.3, and a large ML 7.1 aftershock event occurred 6 hours afterwards, which caused the vertical shift of 350 mm in the TG record that reflected a vertical crustal uplift. We simulate the amount in this event based on the focal mechanic reconstructed by Chen et al. [1997]. The result shows the TG location had a -100mm coseismic vertical drop in contrast with the observed 350mm uplift, apparently because of the sparse seismometer distribution and the resultant mis-locationing of the epicenter. Furthermore, we use the gridding search method to relocate the epicenter which fits the TG observation, putting the epicenter along the onland portion of the active Meilun Fault nearby the downtown of Hualien.
| Identifer | oai:union.ndltd.org:TW/097NTU05274017 |
| Date | January 2009 |
| Creators | Chieh-Chung Chiang, 姜介中 |
| Contributors | Emmy T.-Y. Chang, 張翠玉 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 88 |
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