Crustal Velocity Structure of the Philippine Sea Based on the Obs Survey

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Project title

Code/計畫編號

NSC97-2116-M019-006

Translated Name/計畫中文名

台灣與菲律賓的地體動力學研究---菲律賓海地殼速度構造之海底地震儀震測研究

Project Coordinator/計畫主持人

Tan-Kin Wang

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Institute of Earth Sciences

Website

https://www.grb.gov.tw/search/planDetail?id=1677180

Year

2008

Start date/計畫起

01-08-2008

Expected Completion/計畫迄

31-07-2009

Bugetid/研究經費

1764千元

ResearchField/研究領域

地球科學

"本計畫將配合美國大型震測船(R/V Marcus Langseth)在2009 年4-6 月來到台灣海域進行多頻道震測，而在台灣東部之菲律賓海進行海底地震儀與陸上測站的海陸聯合震測。我們預計使用海研一號與水試一號沿著東西向分別跨越琉球弧前海盆、耶雅瑪海脊、花東海盆佈設與回收40 部海大精巧型海底地震儀與10 部法國海底地震儀。此外，我們也將沿著南北向跨越沖繩海槽、琉球島弧、琉球弧前海盆、耶雅瑪海脊、琉球海溝、西菲律賓海盆佈設與回收40 部海大精巧型海底地震儀與20 部法國海底地震儀。計畫執行的第一年將著重於協調美國、法國、台灣等不同型態約100 部海底地震儀在台灣周圍海域的施測工作，並領導菲律賓海的海底地震儀震測實驗。第二年計畫則將著重於分析菲律賓海的海底地震儀震測資料建構地殼P 波速度模型以期探測耶雅瑪增積岩體的幾何型態、地震滑脫面的分布、隱沒板塊的變化、上覆板塊的岩漿活動、加瓜海脊的隱沒與菲律賓海盆的地殼構造等。這些成果對於板塊隱沒地震為何集中於南澳海盆下方以及和平海盆下方為何有滑移斷層型態的強烈地震都能有較清楚的了解。第三年計畫則將著重於整合分析海底地震儀與陸上測站的震測資料建構海陸P 波速度模型以期探測中央山脈下方可能深達50 公里的莫荷面與海陸交接處之大陸地殼隱沒構造。本計畫完成的台灣南部海陸交接處地體速度模型可使我們瞭解台灣造山運動的演化與板塊隱沒碰撞的詳細機制。例如，海陸板塊交接面、地殼構造面與隱沒板塊斷裂的可能性等。若能配合地震震源分佈與斷層面機制進行綜合解釋，則根據本研究的地殼速度-界面模型亦可判定海陸交接面的地震斷層活動。" "During April-June of 2009, a large seismic vessel of R/V Marcus Langseth will visit Taiwan for conducting a multi-channel seismic survey. With the aid of the large air-gun shots from R/V Marcus Langseth, this project will be able to collect offshore-onshore seismic data in the Philippine Sea off eastern Taiwan using ocean-bottom seismometers (OBS) and land stations. We will deploy and recover 40 NTOU micro-OBS and 10 French OBSs across the Ryukyu forearc basins, Yaeyama Ridge and Huatung Basin onboard R/V Ocean Researcher I and R/V Fisher Institute I. Furthermore, we will operate 40 NTOU micro-OBS and 20 French OBSs across the Okinawa Trough, Ryukyu Arc, Ryukyu forearc basins, Yaeyama Ridge, Ryukyu Trench andWest Philippine Basin. The first year of the project will be emphasized at coordination of seismic surveys off Taiwan for employing about 100 different OBSs from US, French, Taiwan, and we will lead the OBS experiment in the Philippine Sea. The task of the second year of the project will be at processing OBS data for constructing the crustal P-wave velocity models in the Philippine Sea and for investigating the geometry of Yaeyama accretionary prism, the decollement, the subducting slab, magmatism of the overlying plate, subduction of Gagua Ridge, and the crustal structure in the Philippine Sea. The aims of the research are to understand why the earthquakes along the subduction interface accumulate below the Nanao Basin, and why strong earthquakes with strike-slip faulting occur below the Hoping Basin. The task of the third year of the project will be at processing and integrating seismic data of OBS and land stations for constructing the offshore-onshore P-Wave velocity model and for investigating the Moho depth below the Central Range and the possibility of the continental subduction below the Coastal Range. Evolution of the Taiwan mountain-building and mechanisms of the plate subduction-collision can be clarified from the velocity models offshore-onshore Taiwan in this project. For example, we can identify the plate boundary, the crustal interface and the possibility of the slab break-off. Velocity-interface model of this project will also assist us to interpret the earthquake faulting at the plate boundary from earthquake hypocenters and focal mechanisms."

Keyword(s)

地殼速度模型
海底地震儀
海陸震測
隱沒碰撞
crustal velocity model
ocean-bottom seismometer
offshore-onshore survey
subduction-collision

DSpace CRIS

Crustal Velocity Structure of the Philippine Sea Based on the Obs Survey

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