二十公里深臺灣地殼的最強地震圓弧雙交叉分析：不同地震規模設定下的強震預測效果;Analysis of SDICAE in the crust of Taiwan with the depth of twenty kilometers: the efficiencies of strong earthquake prediction corresponding to different choices of event magnitudes

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Title:	二十公里深臺灣地殼的最強地震圓弧雙交叉分析：不同地震規模設定下的強震預測效果;Analysis of SDICAE in the crust of Taiwan with the depth of twenty kilometers: the efficiencies of strong earthquake prediction corresponding to different choices of event magnitudes
Authors:	張萱瑋;Chang, Hsuan-Wei
Contributors:	土木工程學系
Keywords:	最強地震圓弧雙交叉;地震預測;the strongest double intersection of circular arcs of earthquakes;earthquake prediction
Date:	2022-08-22
Issue Date:	2022-10-04 10:47:37 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究使用李顯智老師撰寫的MATLAB程式ASICAE分析李老師所提出之最強地震圓弧雙交叉(SDICAE)概念並觀察後續規模5.7以上強震發生之規律。我們設定地震搜尋期間為西元1980年至西元2016年，地震震源深度為0至20公里，選定時間點向前搜尋之時間長度為四年(dY=4)，精度之弧向誤差參數(TOLdePar)為0.09至0.15，徑向誤差參數(TOLRePar)為0.012至0.016，地理搜尋範圍為北緯21.7度至25.5度，與緊貼臺灣本島西部海陸交界處之斜直線至東部海陸交界處之斜直線，藉此將搜尋SDICAE的範圍盡量限縮於臺灣本島以內，並且將搜尋地震規模(Mmin)最小值由4.9至2.0逐漸調降，進而成功預測到部分臺灣本島內歷史上較具指標意義之災害性地震。另外，在搜尋地震規模最小值設定為2的條件下，發現當弧向誤差設定在0.09至0.11而徑向誤差為0.014至0.016的區間時，雙凸交叉呈現優良的七十天內強震預測效果；而當弧向誤差為0.11至0.15與徑向誤差為0.012至0.014的區間時，凹凸交叉亦呈現優良的七十天內強震預測效果，最佳可達100%預測命中率；隨後，加入特殊篩選機制，刪除半徑比值過大之交叉，亦使短天期的預測命中率更加提升。例如，在刪除半徑比值大於1.4的凹凸交叉後，利用餘下的七個凹凸交叉進行四十天內的強震預測，命中率達到57%。;We apply the MATLAB program ASICAE to search for the strongest double intersections of circular arcs of earthquakes (SDICAEs) proposed by Hin-Chi Lei and analyze the rules of the strong earthquakes with magnitudes over 5.7 occurring after the SDICAEs. The search period is set from 1980 to 2016 and the focal depth is from 0 to 20 km. We look for the SDICAEs formed by events occurring in four years (dY=4) while the arc-direction error (TOLdePar) is from 0.09 to 0.15 and the radial direction error (TOLRePar) is from 0.012 to 0.016. The search area is from 21.7°N to 25.5°N and is bounded by two oblique lines cutting the eastern and western sea-land borders of Taiwan and confining the search area for the SDICAEs to a region containing mainly the island of Taiwan. Furthermore, we gradually reduce the minimum value of the event magnitude (Mmin) from 4.9 to 2.0, and thus successfully predict some historical strong earthquakes in Taiwan by using the SDICAEs. In addition, it is found that the strongest double-convex intersection of circular arcs of earthquakes (SDCICAE) shows an excellent prediction of strong earthquakes within 70 days when Mmin equals 2, TOLdePar is from 0.09 to 0.11, and TOLRePar is from 0.014 to 0.016. Similarly, the strongest concave-convex intersection of circular arcs of earthquakes (SCCICAE) also shows an outstanding prediction of strong earthquakes within 70 days when Mmin equals 2, TOLdePar is from 0.11 to 0.15, and TOLRePar is from 0.012 to 0.014. For some of the settings of precision parameters, the best hit rate can reach 100%. Moreover, a special screening method by deleting the intersections with large radius ratios is adopted to increase the hit rate of short-term prediction. For example, after deleting the SCCICAEs with the radius ratios greater than 1.4, there are only seven SCCICAEs remained and it is found that these SCCICAEs provide a better efficiency of prediction of strong earthquakes within 40 days, and the hit rate reaches 57%.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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