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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/61475

    Title: 利用短週期臨時地震觀測網分析菲律賓明多洛島地震分佈;Analysis of seismic distributions in Mindoro, Philippines using array observations
    Authors: 王晨維;Wang,Chen-wei
    Contributors: 地球科學學系
    Keywords: 地震;明多洛島;一維速度模型;earthquake;Mindoro;1-D velocity model
    Date: 2013-08-27
    Issue Date: 2013-10-08 15:13:16 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 菲律賓群島位於菲律賓海板塊與歐亞板塊的板塊邊界,被認為是由兩大陸塊所組成:菲律賓移動帶和巴拉望陸塊。在中新世時期,東南移動的巴拉望陸塊與西北移動的菲律賓移動帶碰撞為新生代菲律賓群島最主要的構造演化事件,這也可能是馬尼拉海溝初始的隱沒(Yumul et al., 2003)。本研究區域明多洛島就位於馬尼拉海溝的南部末端,代表著巴拉望陸塊與菲律賓移動帶的碰撞邊界,地震分佈呈現陡峭的班尼奧夫帶,確切的巴拉望陸塊與菲律賓移動帶在明多洛島的邊界演化仍然有爭議,本研究主要探討明多洛島當地地震分佈與地震應力,提供地球物理資料的證據幫助解決邊界爭議問題。
    為了解決這個問題,經由菲律賓火山地震觀測所(PHIVOLCS)的協助,我們從2010年的四月開始部屬了10部短週期地震儀,2010年四月至2011年四月的資料已經回收並以台灣地震科學中心(TEC)所提供的地震資料處理軟體Antelope加以處理。藉由在當地架設地震觀測網定位的結果,經由篩選過後地震數量為602筆,大於當地火山地震觀測所同時期、同地區地震數量208筆。地震事件大部分座落在明多洛島西北離岸,深部隨著西南到東北,延伸至200公里,而地震活動到了明多洛島中部及南部,地震事件最深的深度不超過50公里深,說明地震分佈趨勢的不同。我們也從GCMT(Global Centroid Moment Tensor)地震目錄下看到明多洛島西北離岸的地震群集大部分為逆斷層機制,而中南部明多洛島附近則是大多以走向滑移斷層機制的地震事件。
    由地震應力狀態以及地震分佈趨勢的改變顯示明多洛島大致處於兩運動應力狀態:(1)明多洛島西北離岸-碰撞隱沒與(2)明多洛島中南部-西北水平方向塊體運動,在兩個應力機制轉換的邊界位置初步推測可能是位於Abra de Ilog 到 Mamburao,縱谷地形的位置。碰撞邊界演化問題上,Marchadier and Ragin (1990)提出沿著馬尼拉海溝至明多洛島南部有一左移走向滑移斷層於上新世活躍,覆蓋掉中新世時的碰撞邊界至明多洛島北部離岸的位置,由分析地震資料顯示中南部明多洛島正處於西北方向推擠,支持著Marchadier and Ragin (1990)所提出的演化過程。
    The Philippine archipelago is considered to be made of two blocks: the Philippine mobile belt (PMB) and Palawan continental block (PCB). Collision of south-moving PCB and NW-moving PMB during the Early to Middle Miocene (Marchadier and Ragin, 1990) is a major event in the Cenozoic evolution of the Philippine archipelago, which may have initialized the Manila trench (Yumul et al., 2003). The island of Mindoro sitting in the southern termination of the Manila trench represents current location of PMB-PCB collision, which exhibits vigorous seismic activities featuring steeply dipping Wadati-Benioff zone, perhaps as a result of entire consumption of oceanic lithosphere. While the exact PCB-PMB boundary in Mindoro remains in debate, knowing the in-situ seismic distributions can understand the partition of collision stresses and geometry of subducting slab. Both are helpful in resolving the dispute.
      To tackle the issue, we progressively deployed a short period seismic array of ten stations since Apr. 2010. Data between Apr. 2010 and Apr. 2011 have been collected and built into database with Antelope Package. Those events with more than three P readings and at least one S reading were located with results stored in catalogue. In this study, we present the resulting seismic distributions in northwest Mindoro. The number of earthquakes in our catalogue is much greater than those of PHIVOLCS catalogue for the same region during the same period – 605 to 281, attributable to the deployment of our network. Most events distributed clustered in the NW Mindoro, with depth extending to about 200 km featuring a smeared steeply dipping slab. Seismicities fade toward central and southern Mindoro with the deepest event no more than 50 km. Using picking arrival times, we apply VELEST (Kissling et al., 1994) to invert for 1-D velocity model beneath NW Mindoro. The tentative results indicate a velocity jump at about 40 km.
    Appears in Collections:[地球物理研究所] 博碩士論文

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