利用密集臨時地震網對1991至2004年苗栗-台中一帶地震重新定位之研究; Relocation of Earthquakes in the Miaoli-Taichung Area from 1991 to 2004 by a Dense, Temporary Seismic Network

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題名:	利用密集臨時地震網對1991至2004年苗栗-台中一帶地震重新定位之研究;Relocation of Earthquakes in the Miaoli-Taichung Area from 1991 to 2004 by a Dense, Temporary Seismic Network
作者:	何俊瑋;Chun-Wei Ho
貢獻者:	地球物理研究所
關鍵詞:	測站修正;聯合震源定位法;中央氣象局地震觀測網;臨時地震網;重新定位;station correction;joint hypocenter determination method (JHD);Central Weather Bureau Seismic Network (CWBSN);temporary seismic network;relocation
日期:	2005-07-06
上傳時間:	2009-09-22 09:55:29 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	本研究區域位於台灣西部人口密集的新竹到台中之間。在以往的地震記錄中，有較明顯和嚴重的災害性地震為1935年的新竹－台中烈震。自此之後，就沒有再出現過較大規模的地震活動。為進一步了解在七十年後的今日這個地區地震活動的情形，本研究特設置了一個密集的臨時地震網，目的是希望能與中央氣象局的地震資料相互結合，以便對測定小區域的地震活動能有更好的控制。另外增用JHD重新定位方法，以有效改善因採用一維速度模型做定位時，真實地下速度在側向速度變化上之影響。JHD重新定位前後，地震位置會從高速度區往低速度區方向偏移。此外JHD在重新定位過程中，可對每個測站計算出測站走時修正值。利用這些測站修正值來修正1991至2004年氣象局在本研究區域內所測定的地震在各測站的觀測到時，並加以重新定位。結果顯示在用相同定位程式（Hypo71）與固定一維速度模型（陳燕玲，1995）下，若加入測站修正值，確能有效改善定位品質。另外，自1991年後在本研究區域內之地震活動，顯與1935年地震序列在空間上並無重疊現象。在集集地震後所出現之地震密集區應是集集地震之餘震活動。　　The present study area is located between Hsinchu and Taichung in western Taiwan, where is densely populated. From historical records, the 1935 Hsinchu-Taichung earthquake was the last disastrous earthquake in the area. Since then, there has been relatively quiet seismically. In order to study the regional seismisity 70 years after the 1935 event, we deploy a dense, temporary seismic network. It is designed to combine with the earthquake data of the Central Weather Bureau, in order to obtain better control in locating seismicity in the small area. In addition, we also apply the joint hypocenter determination method (JHD) to efficiently improve the earthquake location by minimizing the influence of lateral variations in the one dimensional velocity model. After JHD relocation, the epicenters are moved from the higher-velocity area in the east to the lower-velocity area in the west. Furthermore, JHD can calculate the station correction of travel time for each station during the relocation process. With these station correction data, we can relocate the earthquakes determined in the study area by CWBSN from 1991 to 2004. Using the same location program and 1D velocity model, we can significantly improve the quality of location by adding station correction. Finally, the seismicity in the study area since 1991 apparently does not overlap in space with the 1935 earthquake sequence. It appears that the highly active seismicity in study area either belongs to aftershocks of the 1999 Chi-Chi earthquake, or small earthquakes induced by it.
顯示於類別:	[地球物理研究所] 博碩士論文

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