| 摘要: | 本研究計畫為綜合計畫主持人及共同主持人：中研院地球所 趙里副研究員等人之研究計畫。本計劃擬發展以彈性震波傳遞為主軸的波形逆推方法。針對二、三維震源與速度構造成像理論與實作發展出一套以波埸模擬為主軸的單一地物逆推方法進行複雜構造成像與模擬的前緣研究。利用天然地震與人工震源所收錄波形資料的不同特性，分別進行震源破裂時間-空間形貌與深部構造的逆推。同時，亦擬透過台灣寬頻地震網進行深部莫荷面三維空間分布的分析與研究工作。目前莫荷面的議題已有兩篇文章發表。台灣地區大尺度深部地殼與地體孕震帶的相關研究，過去的工作主要集中在資料的統整與分析上。如何運用初步資料的分析結果及有效的運用地震（被動式震源）與寬角度震測資料（主動式震源）從事重要的科學研究？是未來研究趨勢的重要考量。波場的模擬與逆推法的準備、發展、測試及後續相關資料的應用，均為本計畫的工作重點。計劃的目的將包括：理論與技術發展：(1)發展二維聲場逆推系統及應用於海陸域震測資料。 (2)著重於由二維的問題延伸為三維，評估數值模擬理論基礎與數值法的適用性，地震震波傳遞的數值法的研發、硬體計算平台的建置等問題。(3)結合理論與計算地震學，發展平行計算技術使其成為應用於本計劃的主題研究工具。(4)在探討彈性波場；黏聲性與黏彈性波傳理論的研究上，將強調透過理論與數值計算，評估數值模擬理論基礎與數值法對不同科學問題的適用性，使用的數值模擬方法將包含SEM (Spectral Element Method),改進後的高階、錯位格點FDM (Finite Differencemethod) 與PSM (Pseudospectral Method)等。實際應用目標： (1)針對探索深部地体構造形貌及側向速度變化的研究目標，進行全波形逆推與成像研究。(2) 主動與被動性震源的時間-空間形貌，幅射能量的分佈，震源破裂特性時空變化等科學課題的探討，(3)探討地震震波受震源、路徑及場址放大效應等基本因素，逐一加以釐清，進而未來能進行強震預估。(4)根據接收函數訂定Conrad 與Moho 不連續面的地下三維形貌分布。 (5)承續TAICRUST 計劃的研究，擬嘗試以全波場逆推的方式處理海域與陸域炸測資料。主要的目的為結合所收錄的高頻、海、陸震測資料，透過逆推理論進行地下構造的探索與構造成像。(6)對振幅衰減應受距離、深度、頻率等的影響加以定性及定量的分析，並評估逆推的可行性。同時，本計畫擬透過TEC架構與其他學術研究組群分工合作。在深部地體構造探索的研究議題上，預計執行期間將參加2006-2009 年TAIGER 計畫的工作。按資料的特性，如以被動式地震資料為主軸，進行震源與深部孕震構造的探索與逆推。透過TSMIP 或線型地震網陣列的配置，本計劃預計將運用波場模擬與反演方法進行資料的分析與相關研究，如以接收函數，針對莫荷面的成像研究等。除從事被動式震源所收集的地震資料進行模擬與逆推成像外，為承續TAICRUST 計劃的研究，在研究方法的應用上擬嘗試以主動式、海或陸域寬角度震測資料為對象，進行己知震源特性的全波場逆推。主要目的為針對收錄的炸測資料建立，高解析度速度模型與波場格林函數資料庫，並透過逆推理論進行地下構造的探索。透過方法的研發、程式的發展及確認逆推方法的穩定度等，進行台灣地區震源與區域速度分佈的逆推與資料模擬。必要時，需結合TAIGER與1995 年海陸聯合炸測（TAICRUST計畫）廣角度陸、海域震測資料，進行資料的處理、逆推及相關成果的發表。本計劃預計運用波場模擬與反演法進行資料的分析與相關研究。除預計參加國際合作計劃（TAIGER）或經國內自行整合的計劃進行主動式海域震測資料逆推成像外，大尺度波場模擬，將著重於地形效應與複雜構造對強地動資料的影响。目前已初步完成聲波逆推基本程式與撰寫，測試。實質二維震測資料的分析工作己著手進行。擬持續進行彈性波場逆推程式的發展與測試。同時培養參與本計劃博、碩班研究生所需的實際資料處理經驗。 This proposal is mainly organized by TEC organization under the newly established research subject: computational seismology research. The current proposal is a combination of two personnel including principal investigator: H.W. Chen and Co-principal Investigator: Zhao Li of IES-AS. The proposed methodology is a multi-purpose research plan by combining three major tasks using unified approach for simultaneous source rupture and crustal structure imaging through full waveform inversion. Two major field data resources are: using broadband strong motion data from both Bats/TSMIP and wide-angle seismic data collected from the past or from a newly initiated TAIGER (2006-2008) international project. In the past 30 years, earthquake researches in Taiwan are mainly on data collection and related fundamental researches. However, more important issues including promoting and demonstrating research capability for various scientific targets are obviously more important for the next generation in terms of seismology research in Taiwan. Drawing good science out from the abundance of earthquake and wide-angle seismic dataset is apparently more important, under the condition that if we have a good computing system to start with. Having hardware facility constructed for various research topics is only an essential. The objectives of the proposal are: Theoretical studies and development: (1) to extend the previous work of 2-D to 3-D. Theoretical development, test and evaluation of various wave simulation codes. (2) Enhance the strength of computational seismology for better understanding of realistic wave propagation phenomena, (3) hardware facility and parallel computing algorithm will be the main tool to be developed for practical applications. Practical applications are: (1) to explore the spatial and temporal finiteness of an earthquake source and the three-dimensional heterogeneous earth structure. (2) To investigate source, path and site responses including topography effects; amplification due to effects of shallow soil/sedimentary layers, basin shape, lateral velocity variation, Q distribution and/or others. (3) To perform prestack imaging for both wide-angle land and MCS/OBS marine seismic data (4) to simulate earthquake source mechanism and rupture process when large earthquake occurred under or in the immediate vicinity of Taiwan Island. (5) Apply receiver function analysis to explore 3D Conrad and Moho geometries beneath Taiwan Island. (6) To investigate the effects of attenuation as the function of distance, depth, frequency, scattering and the feasibility of reverse-time wave propagation or inversion. Accurate seismic modeling, both time-domain computations of acoustic, elastic, viscoacoustic and viscoelastic responses will be developed, tested and evaluated. Current 3D spatial distribution of P-, S-velocity will be studied, modified, and evaluated. Effects on source mechanism, propagation, and site response due to local geology and topography changes will be studied. The proposed research is to study 2D and 3D anelastic seismic responses. Numerical model building is a pre-requisite for prestack forward modeling. For field data study, we will focus on strong motion records that are widely available through TSMIP and data management system (DMS) since 1990. Another source of wide-angle seismic data will potentially from the study of ocean-bottom seismograph and multi-channel marine seismic data from TAICRUST experiment in 1995 and a newly approved TAIGER project (2006-2008) through international cooperation. The PIs will actively involve in data collection and assimilation including field works with both onshore and offshore marine geophysicist. The result from both wavefield simulation and inversion will be published in the international journal. The main computation kernel for Wave propagation will utilize SEM, modified high order staggered grid FDM and PSM for different allocated scientific problems. 研究期間：9908 ~ 10007 |
