Crustal Structures of P-Wave Velocity across the Taiwan Strait Analyzed from Obs Data (I)

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Project title

Code/計畫編號

MOST105-2611-M019-002

Translated Name/計畫中文名

海底地震儀震測資料分析跨越臺灣海峽之地殼 P 波速度構造研究(Ⅰ)

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=11903898

Year

2016

Start date/計畫起

01-08-2016

Expected Completion/計畫迄

31-07-2017

Bugetid/研究經費

1466千元

ResearchField/研究領域

海洋科學

第一年計晝利用2015年6月跨越臺灣海峽南部HX07震測線收集的30顆海底地震儀資料以及 2016年6月臺灣海峽中部中線以東施測的15顆海底地震儀資料，分析臺灣海峽的地殼P波速度構造。此外，我們將整合過去幾年在臺灣海峽北部及中部施測的HX06、HX09、HX10和HX12震測線以及 2009年TAIGER計晝在臺南外海佈置的MGL0906-02震測線，建立跨越臺灣海峽的仿三維地殼厚度。目前初步結果顯示跨越臺灣海峽南部HX07震測線的莫荷面深度為30-32公里以及上部地函的P波速度是8.0-8.2公里/秒；而在臺南外海的MGL0906-02震測線莫荷面深度是25-27公里，相較於跨越臺灣海峽的HX07震測線莫荷面深度淺，可能是受到歐亞板塊隱沒到菲律賓海板塊的影響。第二年計晝將從臺灣海峽中部向西南移動到臺灣海峽南部進行海底地震儀震測實驗；第三年則會移往澎湖海盆北邊繼續施測。綜合以上三年計晝以及2009年TAIGER計晝所收集的海底地震儀震測資料，可分析臺灣海峽莫荷面深度、地殼及上部地函P波速度變化，並且釐清臺灣海峽的孕震機制。本計晝的目的是為了探討臺灣海峽的莫荷面深度、岩漿板底抬升、基盤斷層以及構造活動發展的證據，並且增加對本區域地震成因的了解。 In the first year of this project, with the aid of air-gun shooting and explosions, data recorded from 30 OBSs along HX07 line across the southern Taiwan Strait in June 2015 and 15 OBSs deployed southeast of the central line in the central Taiwan Strait in June 2016 will be integrated to image the P-wave velocity structures of the crust. In addition, OBS lines of HX06, HX09, HX10 and HX12 collected previous years in the central and northern Taiwan Strait by China and MGL0906-02 off Tainan during 2009 TAIGER experiment will be considered to build the pseudo-3D crustal thickness across the Taiwan Strait. The preliminary results show the Moho depth of 30-32 km and the mantle velocity of 8.0-8.2 km/s along HX07 in the southern Taiwan Strait higher than those offshore eastern Taiwan. The Moho depth of 25-27 km along MGL0906-02 OBS line off Tainan is shallower than the Moho along HX07 across the southern Taiwan Strait due to subduction of Eurasian Plate beneath Philippine Sea Plate along Manila Trench. OBS experiments in this project will be continuously implemented southwestward across the southern Taiwan Strait in the second year and will be moved to the north of the Penghu Basin in the third year. Integration of OBS data collected all of three years in this project and 2009 TAIGER experiment will lead us to image the velocity variation in crustal layers and the upper mantle at the Taiwan Strait and to interpret seismogenic structures across the Strait. The purpose of this research is to determine the Moho depth, magmatic under-plate uplifting, basement faults and active tectonic development in the Taiwan Strait and for more understanding of earthquake hazards in this region.

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Crustal Structures of P-Wave Velocity across the Taiwan Strait Analyzed from Obs Data (I)

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