The Study of Earthquakes and Tectonic Structures from Southern Taiwan to the South China Sea and the Nearby Region

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Project title

Code/計畫編號

MOST104-2116-M019-002

Translated Name/計畫中文名

臺灣南部至南中國海周邊地區之地震與地體構造研究

Project Coordinator/計畫主持人

Yi-Ling Huang

Funding Organization/主管機關

National Science and Technology Council

Co-Investigator(s)/共同執行人

張文彥
黃瑞德
黃柏壽

Department/Unit

Institute of Earth Sciences

Website

https://www.grb.gov.tw/search/planDetail?id=11485084

Year

2015

Start date/計畫起

01-08-2015

Expected Completion/計畫迄

01-07-2016

Bugetid/研究經費

934千元

ResearchField/研究領域

地球科學
防災工程

"臺灣南部至南中國海周邊地區的地體構造牽涉到臺灣島的形成與未來演化，其中一個重要構造即馬尼拉隱沒構造，其由北緯13 度沿著呂宋島的西側向北伸展至北緯23 度左右，聚合速率可高達每年8 至9 公分。前人研究顯示，以北緯20 度為界，以南之馬尼拉隱沒系統仍為較單純的板塊隱沒環境，以北的區域已逐漸轉變為隱沒跟聚合碰撞同時出現的環境，約於北緯 21 度後，其形貌完全失去海溝所具有的特徵，因此有研究主張馬尼拉海溝並未向北延伸進入臺灣南部及西南海域。受限於此區域為海域、野外資料的收集不易，過去在此區域的研究仍屬較少，且外海地震受限於網外地震定位上準確度不足，無法對此區域深部地殼構造及孕震機制解釋提供良好幫助。本研究團隊過去已使用中研院地球所於TAIGER（TAiwan Integrated GEodynamics Research）計畫執行期間佈設於臺灣陸上之線性陣列所收集到之三群位於墾丁外海的地震群資料、加上IRIS（Incorporated Research Institutions for Seismology）及NEIC（National Earthquake Information Center, USGS）等單位之全球網資料，並結合TAIGER 計畫執行期間於臺灣南部海域進行多次震測所求得的地下速度構造剖面，對此區域內三群地震群重新定位。本計畫預計再結合近年來中研院地球所研究團隊於此區域週邊地區佈設之寬頻地震站所收集之地震資料、加上海峽兩岸簽署之研究合作協議下可提供之西沙、海南、廣東、廣西等測站資料，挑選規模較大的地震嘗試求取震源機制解，探討其震源、發震機制、與馬尼拉隱沒系統及各斷層系統之間的關係，藉以釐清此區域地體構造與臺灣島形成之關聯。" "The tectonic structures in the region from southern Taiwan to the South China Sea and the nearby region are complicated and involved into the formation of Taiwan orogeny. The most well-known structure in this region is the Manila Subduction System. It is toward from south (13°N) to north (23°N) and the velocity of convergence can be 8 to 9 cm/yr. In the part which is to the south of 20°N, the system shows a pure subduction environment. It shows a subduction and convergence mixing environment in the part which is to the north of 20°N, especially the part to the north of 21°N, the system represents a pure convergence- collision feature. Thus, some researchers suppose that the Manila trench does not extend into southern Taiwan area. Due to the limitation of doing the field work in offshore area and the data collection is not easy as onshore, researches about this region are fewer. In addition, offshore events usually occur outside of observational network, it causes uncertainty of doing location calculation and difficult to provide useful information for discussing the seismogenic mechanism in this area. Our group has combined the records of a linear array which were set during TAIGER（TAiwan Integrated GEodynamics Research） project, the data comes from IRIS (Incorporated Research Institutions for Seismology), and the data comes from NEIC (National Earthquake Information Center, USGS) to relocate the events of three offshore earthquake swarms which occurred in this region. The aim of this study is going to combine the data recorded by broadband seismometers which were set by the research group from IESAS (Institute of Earth Sciences, Academia Sinica) around this region and the larger events of broadband data will be selected for focal mechanism calculation. The results of relocation and focal mechanism will provide better evidences for discussing the relationship between source mechanism, plate tectonics, Manila subduction system and Taiwan orogeny."

Keyword(s)

南中國海
馬尼拉隱沒構造
震源機制解
South China Sea
Manila subduction system
focal mechanism

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The Study of Earthquakes and Tectonic Structures from Southern Taiwan to the South China Sea and the Nearby Region

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