研究生: |
趙子凱 |
---|---|
論文名稱: |
集集地震前後震波衰減強度變化之研究 |
指導教授: |
陳光榮
Chen, Kuang-Jung |
學位類別: |
碩士 Master |
系所名稱: |
地球科學系 Department of Earth Sciences |
論文出版年: | 2001 |
畢業學年度: | 89 |
語文別: | 中文 |
論文頁數: | 73 |
中文關鍵詞: | 集集地震 、震波衰減 、時間變化 |
論文種類: | 學術論文 |
相關次數: | 點閱:187 下載:8 |
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摘 要
1999年九月二十一日一個規模超過7.0的大地震(Mw=7.7,ML=7.3)發生在台灣中部靠近集集鎮附近。到目前為止起碼超過15,000個餘震被記錄到。其中有200個以上的有感地震,規模大於6.0以上則有十個之多,是有史以來餘震最多的一個。在本研究中,我們分析發生在餘震區內的地震紀錄,計算從主震前20個月至主震後9個月內,該區域內衰減強度的時間變化,利用每一個測站量測的S波最大振幅所得出的的地區規模(local magnitude,ML),與平均地區規模作比較。首先分析各測站的規模差異量delta ML隨時間變化情形,並比較各測站在震前、震中及震後delta ML)的平均值變化情形。結果顯示,餘震區內在主震後有十個測站的(delta ML值降低,有五個測站delta ML值增加。其次分析delta ML的空間分佈,發現台灣地區的delta ML在主震前後並沒有太大的改變,反而在餘震區內則有顯著的變化。最後計算出餘震區的 1/Qs 值在主震後比主震前略為增加。
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