碩士 / 國立中央大學 / 地球科學學系 / 104 / The southern Ryukyu subduction system is located at the boundary between the Philippine Sea Plate (PSP) and the Eurasian Plate (EUP). The Philippine Sea Plate subducts northwestward beneath the Eurasian Plate near the eastern offshore of the Taiwan orogen. The Ryukyu subduction system is potentially hazardous in terms of tsunami and ground shaking for Taiwan region. Therefore, it is important to understand the crustal structure of this subduction system. In previous studies, the geometry of the subducting PSP is not clear, so we want to process high-resolution crustal-scale seismic images. However, crustal reflections are usually covered by the multiples from sea floor. In order to imagine the plate boundary or even moho reflection, the advanced multiple attenuation methods need to be applied for studying the crustal deformation in the subduction zone. In this study, we applied the multiple attenuation methods to the multi-channel seismic profiles (MGL0906_18N；MGL0906_15N；MGL0906_30A) in the southern Ryukyu subduction system from TAIGER (Taiwan Integrated Geodynamic Research) project in 2009. The field experiment parameters are 50 m shot interval, 12.5 m spacing for the hydrophone, 15 s of recording time, and 6.25 m of CDP spacing. In those profiles, the top of subducting crust of the Philippine Sea Plate is hidden by the multiples. Due to multiples affect on the deep structure signals, we use several de-multiple methods to remove the multiple effects, and increase signals from deep crustal reflectors. In this study, four steps of multiple attenuation methods are used (1) 2D Surface Related Multiple Elimination (SRME), (2) Radon Transform multiple attenuation, (3) Predictive Deconvolution, (4) Dip filter. After these steps, the top of subducting plate below the accretionary prism and the east Nanao basin is clearly imaged. Those methods can be applied to other marine seismic profiles in the future.
| Identifer | oai:union.ndltd.org:TW/104NCU05134014 |
| Date | January 2016 |
| Creators | Ci-Jhu Lyu, 呂奇祝 |
| Contributors | Hao Kuo-Chen, 郭陳澔 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 139 |
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