云南宾川大容量气枪震源波形频谱特征分析

Large volume air­gun source spectrum characteristics of Binchuan，Yunnan

摘要:

2011年云南省地震局、中国地震局地球物理研究所在云南省宾川县大银甸水库开展了大容量气枪激发实验。为了深入研究气枪震源激发波形的特征，本文对不同距离台站记录的波形进行了频谱分析，对气枪激发震源的能量进行了计算，并将彩凤台气枪信号的波形、频谱特征与天然地震进行了对比分析。结果表明，1次激发相当于ML0.7的天然地震。对相近震级天然地震波形的频谱与气枪激发波形的频谱进行对比后发现，气枪震源激发波形频率小于15Hz，主频多数集中在2～5Hz；气枪震源激发的地震波中低频信号较相当震级的天然地震明显；1次激发释放的能量为8.90×106J，相当于2.4kg硝铵炸药的当量。

关键词:气枪震源 频谱特征 天然地震 对比

Abstract:

A field experiment using large air gun source was conducted in the Dayindian reservoir of Binchuan，Yunnan by Earthquake Administration of Yunnan Province and Institute of Geophysics，CEA in 2011 in order to further study the characteristics of its spectrum. Firstly，we analyzed the spectrum features of each station from different distances. Secondly，we calculated the energy of air-gun excitation. Thirdly，we compared the characteristics of air-gun signal with the natural seismic wave. The result indicated that an excitation can result in a level equivalent to that of a ML0.7 nature earthquake. The signals of air-gun have a 2～6Hz dominant frequency and less than 15Hz. The signals by air gun have a stable frequency and is rich in low frequencies. The release energy by air gun which is equal to 2.4kg ammonium nitrate explosive energy is 8.90×106 J.

Key words:Air­gun sources; Frequency feature; Natural earthquake; Contrast