- 學位論文
由尾波探討雲嘉南地區的散射衰減與吸收衰減
Investigate The Absorption Attenuation and Scattering Attenuation in The Southwest Taiwan by Coda Waves
摘要
摘 要 本文利用能量通量模型(Energy flux model)來估計雲嘉南地區的吸收衰減(intrinsic attenuation)與散射衰減(scatter attenuation)。將記錄中的尾波，藉由取對數並做完幾何修正與散射修正後，可以用斜率、截距來換算Q值。此處理訊號的方式經由人工合成函數測試後証明可行，適用於任何範圍內的Q值。我們以發生在雲嘉南地區，2006年至2009年之間，23個規模(ML)4-5的地震資料來分析，共計有427筆地震紀錄。並將每筆地震紀錄做共七個頻段的濾波，方便我們用來計算頻率與Q值的關係式。 我們先將所有記錄一並統計計算出雲嘉南的Qi( f )=135.0 f 0.6、Qs( f )=13.7 f 1.3。接著將所有地震的震央由北至南分區後，我們得到(a)斗六的Qi( f )=123.5f 0.85，Qs( f )=15.7 f 1.33；(b)嘉義的Qi( f )=129.0 f 0.59，Qs( f )=12.2 f 1.40；(c)新營的Qi( f )=152.2 f 0.47，Qs( f )=15.0 f 1.28；(d)台南的Qi( f )=148.1 f 0.52，Qs( f )=12.5 f 1.40。除了斗六的高頻率Qi與其他三區有顯著的差異外，其他部分的Q值大致呈一致的結果。因此推論梅山斷層與九芎坑斷層的地質條件，材料質地較其他地區堅實。除此之外，所有地區的Qi值都比Qs值大，判斷在雲嘉南地區直達波能量的衰減主要取決於散射。
並列摘要
In this study, the energy flux model is used to estimate the absorption attenuation and scattering attenuation in the southwest Taiwan. The recorded coda amplitudes after geometric correction and scatter correction, you can use the slope and intercept to estimate Q values. This behavior of coda waves via artificial synthetic function tests shows that the validity of the method used for any range of Q values. We collected 23 events located in the Southwest region, between 2006-2009, with magnitude (ML) 4-5 . There are total of 427 seismograms. Each record passes seven band-filters to calculate the frequency dependent Q values. From all records statistics we have Qi (f) = 135.0 f 0.6, Qs (f) = 13.7 f 1.3 for southwest Taiwan. According region variation north to the south , we have (a) Qi (f) = 123.5f 0.85, Qs (f) = 15.7 f 1.33 in Douliu area; (b)Chiayi Qi (f) = 129.0 f 0.59, Qs (f) = 12.2 f 1.40; (c) Xinying of Qi (f) = 152.2 f 0.47, Qs (f) = 15.0 f 1.28; (d) Tainan Qi (f) = 148.1 f 0.52, Qs (f) = 12.5 f 1.40. Except for high-frequency Qi in Douliu have significant differences from the other three areas, the other part of the Q value substantially consistent results. Therefore it indicates that Meishan fault and Chiuhsiungken fault geology conditions or materials texture more solid than other regions. In addition, Qi value than the Qs tells us that the direct wave energy attenuation depends more scattering in southwest Taiwan.