臺灣地區 109 年中大型地震震源資訊之快速彙整與提供 The rapid integration of 2020 large earthquake source
information in Taiwan
主管單位：中央氣象局地震測報中心 馬國鳳1，李憲忠2
Kuo-Fong Ma, Shian-Jong Lee
1國立中央大學地球物理研究所
2中央研究院地球科學研究所
摘要
地震風險評估對計算地震損失評估上扮演者重要的角色，而建築物易損性 曲線則為地震災損評估中至關重要之參數。為建立臺灣建物易損曲線，本計畫
首先建立1999 年集集地震及 2016 美濃地震後建築物損害資料庫。根據不同建
築物建材類型，以最大概似法迴歸出最大地表加速度 (PGA)以及最大地表速度 (PGV)下建築物易損性曲線。並對比過去前人評估臺灣地震風險利用 PGA 的易 損性曲線，以過去集集地震及美濃地震實際觀測得到的地動值，計算及對比地 震風險的結果。本研究建立的易損性曲線所進行的風險評估結果除對比過去易 損性曲線評估之結果有所下修外，其美濃地震損失評估結果也較接近於實際災 損評估。未來在相關的後續研究及工作上，可以嘗試將臺灣較新的易損性曲線 與本研究做相關比較，使地震風險相關研究能在未來持續有所改善。
即時地震矩張量監測系統(Real-time Moment Tensor monitoring system, RMT) 結合中心地震矩張量(centroid moment tensor, CMT)逆推、格點搜尋演算法(grid- based search algorithm)以及三維格林函數(three dimensional Green’s function)即時
進行臺灣地區的地震偵測。此系統可於地震發生之後約2 分鐘提供地震報告，
所提供之即時震源參數包含時間(centroid)、位置(centroid)、深度(centroid)、地 震矩規模以及震源機制等資訊。自本年度(2020 年)年初至 11 月中為止，RMT 系 統共偵測得111 筆地震事件，其中最小的地震矩規模(Mw)為 3.1 (氣象局小區域 地震，2020-02-03 00:19 (UTC)，芮氏地震規模 ML2.9)，最大的地震矩規模為 5.3 (氣象局編號 025 地震，2020/05/03 03:24 (UTC)，芮氏地震規模 5.9)，總數略少
於去年同期的126 筆紀錄。比較 RMT 系統及氣象局速報均有紀錄的 56 筆地震
的規模、發震時間及震源位置。考量本系統的結果為中心地震矩，與初始破裂 本存在不同，各項數值的差異均在合理範圍內且大致呈現常態分佈，其中規模 之差值(dM)的平均為 0.39；時間差值(delay time)平均為 1.25 秒；震源深度差值 (dDepth)平均為 5.2 公里；水平震央差值(dEpicenter)平均約為 3.7 公里。
關鍵詞:易損性曲線、地震風險評估、集集地震、美濃地震、即時、地震矩張量、
地震報告
Abstract
The assessment of the seismic risk is an important resource in order to measure the potential losses due to future earthquake, and fragility curve is one of key parameters for the assessment. In order to obtain reliable fragility curves, this project constructed database for the building damage records during the 1999 Chi-Chi and the 2016 Meinong earthquakes. Besides of peak ground acceleration (PGA), we also developed building fragility curves in the forms of other strong motion parameters (i.e., peak ground velocity and the new CWB intensity scale). By using a maximum likelihood method, we estimated the building damage and economic loss in comparison to the previously established PGA-based curves. In this case the reliability of the building damage and economic losses for our result is higher than the estimation from pre-existing fragility curves. The new building fragility curves in different intensity units provide crucial information on modeling seismic risk for Taiwan.
The real-time moment tensor monitoring system (RMT) combines central moment tensor (CMT) inverse, grid-based search algorithm, and three-dimensional Green function to real-time detects earthquake activity in Taiwan. This system provides an earthquake report about 2 minutes after an earthquake occurs. The report includes event time (centroid), location (centroid), depth (centroid), seismic moment scale, full moment tensor, and focal mechanism. From the beginning of this year (2020) to mid- November, the RMT system has detected a total of 111 events, of which the smallest seismic moment scale (Mw) is 3.1, the largest seismic moment scale is 5.3. The total number of earthquake is slightly less than 126 event in the same period in 2019. A comparison between the RMT CMT report and the CWB quick earthquake report is provided. Considering that the result of this system is the centroid seismic moment, which is different from the initial rupture (the hypocenter), the differences of various parameters are within a reasonable range and generally present a normal distribution.
The average of the difference in scale is 0.39; the time difference is 1.25 seconds; the focal depth difference is 5.2 kilometers; the horizontal epicenter difference is about 3.7 kilometers on average.
