本研究首先分析基於震源機制的座標系統的近車籠埔斷層之九個地震觀測站的最大加速度值、最大速度值以及加速度頻譜。結果顯示：除了其中一個的觀測站外，由斷層南段至北段之最大加速度值為遞減，而最大速度值為遞增。雖然加速度頻譜中含有許多複雜特性，從記錄分析還是可以得到一些有價值的結果。造成沿斷層之地震紀錄之變化，主要原因為震源和場址的效應，其中場址效應作用在頻譜之高頻部分，而震源效應則是在低頻的部分。對三個方向的地動主頻，在斷層上盤者高於在斷層下盤者。
In this work, we first study the peak ground accelerations (PGA), the peak ground velocities (PGV) and spectra of acceleration waveforms, based on a coordinate system defined on the focal plane of the earthquake, at nine near-fault seismic stations along the fault trace. Results show that except for a station, near which there is a remarkable change of the fault trace, the near-fault PGA value decreases and the PGV value increases from south to north along the fault. Although there exist variety and complexity in near-fault acceleration spectra, some substantial conclusions can still be retrieved. The source and site effects are two major factors in controlling the variation in near- fault acceleration spectra along the fault. The site effect acts mainly on the high-frequency spectra, while the source effect on low-frequency ones. For the three components, the value of the predominant frequency is, on the average, higher in the hanging wall than in the foot wall.
關聯:
Journal of the Chinese Institute of Engineers 25卷5期 P.507-519
