透過三維震波傳遞模擬探討速度脈衝的生成—以 2016年美濃地震與 2018年花蓮地震為例;Investigating Velocity Pulse Generation through 3 -D Ground Motion Modeling Case Studies of the 2016 Meinong and 2018 Hualien Earthquakes in Taiwan

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Title:	透過三維震波傳遞模擬探討速度脈衝的生成—以 2016年美濃地震與 2018年花蓮地震為例;Investigating Velocity Pulse Generation through 3 -D Ground Motion Modeling Case Studies of the 2016 Meinong and 2018 Hualien Earthquakes in Taiwan
Authors:	楊詠晴;Yang, Yung-Ching
Contributors:	地球科學學系
Keywords:	速度脈衝;地震動模擬;有限差分法;Recipe 方法
Date:	2025-08-06
Issue Date:	2025-10-17 11:47:33 (UTC+8)
Publisher:	國立中央大學
Abstract:	近年研究指出，許多地震事件中常觀測到速度脈衝特徵，該現象被歸因於破裂方向性效應，並與嚴重地震災損密切相關。例如，臺灣的2016年美濃地震與2018年花蓮地震中，均觀測到顯著的脈衝型地震動，並造成建築物的嚴重傾倒。為探討速度脈衝之成因與影響因子，本研究針對上述兩起地震事件作為研究案例，採用三維牽引力鏡像有限差分法進行低頻段地震波傳遞模擬，震源模型方面採用有限斷層模型以及透過Recipe方法建構之特徵震源模型，速度構造模型則考量含地表地形之三維速度構造，並將模擬結果與觀測資料進行比較分析，進一步以脈衝指標判別地震動是否具有脈衝特徵，以及與CH20地震動模型進行比較。結果顯示，震波模擬方法於美濃地震案例較花蓮地震案例對於脈衝波之成因解釋性較高；進一步分析發現，震源模型之地栓幾何與破裂速度對速度脈衝生成影響最為顯著；路徑效應方面，HH_surface速度構造模型(Huang et al., 2014)與HH速度構造模型(Huang et al., 2014，無沉積層)相較不含淺層速度構造的KC速度構造模型(Kuo-Chen et al., 2012)更易於生成脈衝訊號，並強調淺層速度構造對於生成脈衝訊號具有貢獻；而模擬所得的脈衝週期介於1至3秒。綜合以上結果，本研究亦探討震源模型建立方式、經驗式選用與地形解析度對模擬結果之影響，並指出選用適合的方式建立模型之必要性，期望未來能提升預估含脈衝特徵之地震動強度的準確性。;Recent studies have pointed out that many earthquake events frequently exhibit velocity pulse characteristics, which are attributed to rupture directivity effects and are closely associated with severe seismic damage. For example, the 2016 Meinong and 2018 Hualien earthquakes in Taiwan both displayed prominent pulse-like waveforms that led to building collapses. To investigate the causes and influencing factors of velocity pulse generation, this study uses these two events as case studies and performs low-frequency 3-D ground motion simulations using the traction-image finite-difference method. Finite-fault models and characteristic source models constructed using the Recipe method are employed, and 3-D velocity structures incorporating surface topography are considered. Synthetic waveforms are first compared with observations, followed by the identification of velocity pulses using a pulse recognition technique. These ground motions are also compared with predictions from the CH20 ground motion model. Simulation results indicate that the 2016 Meinong earthquake case provides better explanation of the observed pulse features compared to the 2018 Hualien earthquake case. Further analysis reveals that asperity geometry and rupture velocity in the source models have the most significant influence on pulse generation. In terms of path effects, the HH_surface (Huang et al., 2014) and HH (Huang et al., 2014, without sedimentary layer) velocity models are more prone to generating pulse signals than the KC model (Kuo-Chen et al., 2012), and the shallow low-velocity layers in HH_surface model contribute noticeably to pulse generation. Furthermore, the simulated pulse periods range between 1 and 3 seconds. This study also explores the impact of different source modeling approaches, the selection of empirical equations, and the resolution of topographic data on simulation outcomes. It also highlights the necessity of adopting appropriate modeling strategies to enhance waveform modeling accuracy for seismic hazard assessment.
Appears in Collections:	[Graduate Institute of Geophysics] Electronic Thesis & Dissertation

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