2014-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/713761摘要：本計畫為前年所提之多年期研究計畫(NSC101-2116-M-002-027-)中之最後一年期部分。主要利用地震學方法研究高加索地區之速度構造及地震特性，同時加強過去西藏高原的研究，藉由兩區域之對比來探討大陸碰撞的岩石圈演化。西藏與高加有著相似的構造背景相，但由於歐亞-印度碰撞時間較長且有較高的聚合縮短量，西藏可視為成熟的碰撞結果，相對的歐亞與非洲的碰撞較晚，高加索反映碰撞所影響的最北緣。過去在西亞的大陸碰撞相關之地震研究都以大型地震之震源破裂為主，或探討土耳其地區的斷層和岩石圈構造，高加索區域一直缺乏地震觀測資料。申請人過去主要研究西藏下方之岩石圈構造，發現地殼由南往北變薄、羌塘地塊下的地函速度異常及西藏岩石圈剝離卻可能含水等現象，最新研究不但證實大尺度的構造為真，還顯示在拉薩地殼內部的數個地層具有明顯低速異常。申請人甫獲台大補助購置之數台地震儀並已陸續架設於小高加索區域蒐集地震資料，成功地以區域波形逆推法分析在2008-2012間發生的震源機制，本計畫若能繼續獲得國科會支持，高加索(喬治亞與亞美尼亞)地震網得以維護建構，有利跨國、跨領域的合作，此第三年度將著重在完成彙整高加索岩石圈之細部速度構造，並與西藏中部現有研究結果相對比，並分析西藏其他區域之接收函數資料。<br> Abstract: This project may be considered as the 3rd year continuation (also the last year) of our previous proposal (NSC101-2116-M-002-027-). We propose to investigate the velocity structure and earthquake properties beneath the Caucasus region that represent the northern terminus of the collision between Eurasia and Arabia. In the proposal, we also refine the crustal velocity structure under Tibetan plateau, which is the result of Eurasia-India collision. The continental collision in the latter case started relatively earlier and the rate of convergence is higher. As such, the comparative study between these two regions that share similar tectonic context offers a unique chance to understand the process of continental collision. However, previous studies in western Asia focused mainly in Turkey. Little seismic constraints are available in the Caucasus, thus new observations are desired to make important contributions. We have gained lots of experiences through studies in Tibet. We found crustal thickness is thinner and the upper mantle velocity is slower in the northern Tibet. We discovered seismic anomalies in the deep mantle that may be associated with a delamination of Tibetan lithosphere and this detached remnant might be hydrous. New results in Tibet also reveal layers of low-velocities in the crust. Recently, we received funding from National Taiwan University to purchase seismic stations. The deployment of seismic stations in Caucasus is in good progress and new data are being collected. We successfully determined focal mechanisms of earthquakes in 2008-2012 using regional waveforms. We hope NSC can continue the support to maintain the Caucasus array, which also promote international collaborations. Since this is the last year of the 3-year project, we shall emphasize the refinement of detail lithospheric structure beneath the Caucasus, contrasting the results with preexisting studies in central Tibet, and preliminary exploration of receiver functions in other areas in Tibet.西藏高加索大陸碰撞地震波非均向性接收函數地殼地函震源機制解TibetCaucasuscontinental collisionseismic anisotropyreceiver functionscrustupper mantlefocal mechanism