108年度地震資料之分析應用

NCUIR > College of Earth Sciences > Department of Earth Sciences > Research Project > Item 987654321/79162

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/79162

Title:	108年度地震資料之分析應用
Authors:	馬國鳳;梁文宗;郭陳澔;鄭世楠;溫國樑
Contributors:	國立中央大學地球科學學系
Keywords:	井下地震儀;頻譜比;轉換函數;downhole seismometers;spectral ratio;transfer functions
Date:	2019-02-21
Issue Date:	2019-02-21 14:56:48 (UTC+8)
Publisher:	交通部中央氣象局
Abstract:	過去臺灣的衰減式主要是利用地表測站資料來推估，且在衰減式中，以場址分類或是Vs30來考慮地表淺層的場址效應。對於主要建在岩盤站的重要公共工程，例如核電廠等，若以一般的地動衰減式做耐震設計評估，高估的數值將造成巨額的成本，且不足以應付高頻訊號的解析。因此，若能建立岩盤衰減式，且納入轉換函數，將可提供更確實的耐震設計參考，對於瞭解基盤的地動特性也有很大的幫助。於去年度的計劃中，僅使用入射角小於35∘之地震紀錄，求得全台共27個測站之轉換函數，今年將進一步求得上述測站不同頻率段下經地表修正之後的放大倍率。近年來氣象局廣泛建立井下地震儀觀測網，直至2018年，全台已超過50個地表及井下的地震觀測站，在今年度的計劃中，將首先針對近年大規模地震，包含2016美濃地震(ML 6.6)及2018花蓮地震(ML 6.2)，篩選井下地震監測網之可用地震紀錄，評估是否足以建立地動預估式之可能性。另一方面，將沿用去年計畫中所使用之線性水平法，計算全台測站之加速度及速度轉換函數，並對計算出之轉換函數進行深度效應的修正，藉此瞭解全台測站在頻率域之放大特性，並將計算出之轉換函數和去年度計畫的結果進行比較，瞭解震波入射角度與放大倍率之間的關係，並與現有之平均Vs、Vs30速度構造進行比較分析，評估其應用於衰減式之合理性及可能性。地震測站的剪力波速構造對強震資料的應用相當重要，舉凡地動預估式、強地動數值模擬、場址放大效應等研究，都需要精確的淺層剪力波速構造以提高研究結果的精確性。利用接收函數法推求速度構造的研究多使用遠震資料分析深部構造，然而近年來有研究使用區域地震資料的接收函數分析淺部地層波速構造，且能獲得不錯的結果。氣象局近年建置的地表－井下地震網已收集許多地震資料，經資料品質挑選及地震事件與測站的方位角轉換後，即可計算各測站的徑向接收函數，並推估各測站的剪力波速構造，本計畫將延續107年之工作，完成目前共59個測站的淺部剪力波速構造，並從推估的波速構造中擷取出重要的場址參數Vs30和Z1.0。台灣地區深部地震(>70km)芮氏地震規模（ML）之訂定與美國地質調查所所訂定的地震震矩規模（MW）有高估的情形，表示芮氏地震規模之經驗式有修正之必要，因此，此計畫將搜集相關地震目錄資料，重新計算深部地震之芮氏地震規模經驗式。本計畫擬延續106年度與107年度計畫結果，彙整臺灣地區歷史災害地震資料，建置遠古時期(原住民地震神話與傳說)、1486-1899年歷史地震、1900年以後儀器觀測之臺灣地區災害地震目錄。建置的資料包括地震發生時間、震源參數、震度分布以及詳細的災害數據與災害分布等。所得結果將以網頁的方式呈現、除了提供相關地震防救災使用外，並增加中央氣象局地震災害資料庫的資料。本計畫旨在規劃如何建立國際化的地震資料中心，而所謂的國際化指的是(1)資料符合國際標準、(2)服務滿足國際需求、(3)資料產品具國際化趨勢，這也是一個現代地震資料中心的基本配備和責無旁貸的任務。依照這樣的規範來看，要建立一個現代化的資料中心應該在四個面向有具體的作為：(1)即時且穩定的資料收集和典藏平台、(2)自動化的資料品質控管、(3)高效能的網路資料服務系統，以及(4)妥善安全的備份計畫。為了順利進行這幾項工作，除了完善的硬體設備之外，更重要的是形成專業的工作團隊逐步累積知識，做為長期營運現代化資料中心的儲備人才。從管理詮釋資料開始，遵循國際資料標準，開發自動化的線上資料檢索工具程式，最終提供使用者便捷的網路服務系統。 ;The previous ground motion prediction equations (GMPEs) for Taiwan are mainly established by seismic records of surface stations and considered the site-effect of near-surface structure by site classification or site parameters (e.g. Vs30). However, for important public constructions, such as nuclear power plants, which are built in the bedrock, the seismic design is estimated by the general ground motion attenuation equations may be overestimate and cause large cost but not enough to do the analyze the high frequency signals. Therefore, the bedrock GMPE including transfer functions will provide a more accurate seismic design reference, which is also helpful for understanding the ground motion characteristics of the bedrock. The results of the previous year, the transfer functions of 27 stations were obtained, using the seismic records with incident angles less than 35∘. In this year, the amplification factor after depth-effect correction at different frequency segments will be obtained. In recent years, the CWB has extensively installed borehole network stations, there are more than 50 stations until 2018. In this research, we will first analyze two large earthquakes, including the 2016 Meinong earthquake (ML 6.6) and the 2018 Hualien Earthquake (ML 6.2), obtaining the available seismic records of the borehole seismic network to analyze whether it is sufficient to establish a bedrock ground motion prediction equation. On the other hand, the water-level methods will be used to calculate the transfer functions of all stations, and the depth effect will be corrected, to realize the amplifications of the station in frequency domain. The transfer functions will be compared with previous results to realize the influences of incident angles and also compared with the velocity structure, like average Vs, Vs30 to evaluate the possibility of the application to GMPEs. S-wave velocity structure at seismic stations is very important for Ground Motion Prediction Equations (GMPE), strong motion simulations, and site effect analysis etc. Results of those studies can be enhanced if detail shallow S-wave velocity structure is available. Teleseismic data is usually used in receiver function method to estimate deep structure; however, local earthquake data has been used to estimate shallow S-wave velocity structures recently, and the results are reliable. The surface-downhole network has recorded many seismic records. After data quality check and other necessary processing, we are able to calculate radial receiver function and estimate shallow S-wave velocity structures at stations. This project will continue the work in 2018 to estimate shallow S-wave velocity structures at 59 stations and the important site parameters Vs30 and Z1.0 will also be derived. Based on the earthquake catalogue, Richer magnitudes (ML) for deep earthquakes (depth greater than 70 km) are generally larger than moment magnitudes (MW) for deep ones in Taiwan. This is probably due to the high attenuation characteristics of the upper mantle of Taiwan, which results in a relatively high ML when compared to moment magnitude, MW. In this project, we will re-define a ML scale for deep earthquakes (depth greater than 70 km) in the Taiwan region that is more consistent with MW. This plan is to continue the results of the 106th and 107th annual projects, to collect historical earthquake data in Taiwan, to build disaster earthquake catalog of ancient times (the aboriginal earthquake myths and legends), the 1486-1899 historical earthquake, and the instrumental earthquakes after 1900. The data provided include the occurrence time, source parameters, intensity distribution, disaster data and disaster distribution. The results will be presented in the form of a web page, in addition to providing relevant earthquake prevention and disaster relief use, and increasing the information of the Central Weather Bureau earthquake disaster database. To build up a modern seismic data center, we are aiming to achieve the following goals: (1) worldwide standard data format, (2) efficient and open web services, and (3) user friendly data products. This is also a measure of the performance of a modern seismic data center. According to the goals we set for building a modern seismic data center, we propose a strategy which requires (1) a stable data acquisition and archiving platform, (2) an automated data quality control, (3) a high performance web service system, and (4) a secure data backup plan. To make sure this will happen, we need to form a constant taskforce in addition to a robust hardware construction so that we are able to accumulate work experience which will in turn help us to handle the future challenge. In this proposal, we present the way to manage the metadata and international seismic data format at first. Then we design automated utilities for data processing and quality control. Finally we compare some candidate online web services for data requesting in the world and our recommended inferfaces.
Relation:	財團法人國家實驗研究院科技政策研究與資訊中心
Appears in Collections:	[Department of Earth Sciences ] Research Project

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