Preliminary analysis of the ocean bottom seismometers data offshore eastern Taiwan by TAMS program.
| Autor: | Hsin-sung Hsieh, 謝欣崧 |
|---|---|
| Rok vydání: | 2012 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 100 Non-volcanic tremor (NVT), originally identified in the subduction zone of the southwest Japan, has been well studied in the circum-Pacific subduction zones and the transform plate boundary in California. East of Taiwan, the Philippine Sea plate subducts northward beneath the Ryukyu arc. Moreover, an active strike-slip fault along the Taitung Canyon was reported in the offshore eastern Taiwan. In such complicate tectonic environments, NVT behavior could probably bring us more information about the interaction of all the geological components in the area. In this study, we analyze the seismic signals recorded by the Ocean bottom Seismometer (OBS) deployed offshore eastern Taiwan in September 2009. TAMS (Tremor Active Monitor System) software was used to detect the presence of NVT. 330 seismic signals and 26 tremor-like signals were obtained from the 3 weeks recording period. For the tremor-like signals, we re-examine the waveform and the spectrum to remove the false results. Finally, 3 possible tremor intervals exist. We used the SSA (Source-Scanning Algorithm) to map the possible distribution of the earthquakes and tremors. In total, 277 earthquake events and 2 tremors were located around the eastern offshore Taiwan. We compare the earthquakes position with previous study, and both results have one identical NW-ES distribution feature near the mainshock on 2009/8/17. Otherwise, the seismic patterns are not always the same. We believe the difference may cause by the uncertainty of the velocity model and the different relocation method. The 2 tremors are distributed in 2 different areas: the Yaeyama Ridge and Taitung Canyon. Limited by the short recording period of the OBS experiment, we could not obtain any possible repeating interval or the spatial migration about the tremor occurrence. However, the presence of NVT offshore eastern Taiwan shown in our study still brings us valuable understanding about the undergoing tectonic processes in the marine area. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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