藉由產生一個災害景象地震，可以制定有效的政策並且減少一個地區在地震發生之後對於地震災害的影響。經驗格林函數法可以藉由規模較小的地震動來模擬一個規模較大的地震動，而這種方法也可以有效地產生災害景象地震。?2010年台灣行政院國家科學委員會公布了一項研究結果，指出梅山斷層，在未來十年發生芮氏規模7.1以上的強震機率為9.75%，而在未來五十年發生的機率為44.92%。因此，產生梅山斷層所造成的災害景象地震並探討其對嘉義地區的影響是一件當務之急的課題。本研究以前分析法(forward analysis)模擬1999年梅山斷層所發生芮氏規模6.4的地震動，以了解可能的斷層滑動機制，以及一套模擬的流程，並作為一棟三層樓的鋼筋混凝土建築的地震輸入，進行非線性分析，藉以更進一步的比較觀測與合成波型對於結構物的反應。然後根據上述的震源機制，再更進一步的模擬多組芮氏規模7.1的災害景象地震，以來探討不同滑動機制的災害景象地震的影響。經由比較可以得知，波形、地質條件的選擇對於合成的結果有很大的影響。An accurate scenario earthquake motions for a target city or region is of primary importance to develop effective countermeasures to reduce the future earthquake damages.?The empirical Green’s function method (EGFM) which uses the small earthquakes as Green’s function to synthesize large earthquakes has become a useful approach for such a purpose. On January 21, 2010, The National Science Council of Taiwan announced that the probability for this fault to generate an earthquake of magnitude 7.1 is 9.75% within next 10 years and 44.92% within next 50 years.?Thus, the generation of scenario earthquake motions over Chiayi area from Mei-Shan fault becomes a critical task.?In this study, we use forward analysis to simulate an earthquake of magnitude 6.4 which is occurred in Mei-Shan fault in 1999.?In order to further investigate the conformability of the observed and synthesized waveforms, a hypothetical three-story reinforced building modeled as a three-degree-of-freedom lumped mass system, and follow above earthquake mechanism to predict a few scenario earthquakes of magnitude 7.1.?The results show that EGF method can simulate the observed motions at the rock site well. In order to get good agreement, the waveform of green’s function should be as similar as main shock, and the amplitude of observed and synthesized waveform should be same.
