水库气枪震源产生的S波及其分裂  

SHEAR WAVE GENERATED BY AIRGUNS IN A RESERVOIR AND ITS SPLITTING

作　　者：张尉[1,2] 戴恒昌 李向阳 陈棋福[2] 陈汉林[1] 陈颙[2] 

机构地区：[1]浙江大学地球科学系,杭州310027 [2]中国地震局地震预测研究所,北京100036 [3]英国地质调查局,爱丁堡EH9 3LA

出　　处：《地震地质》2009年第1期22-33,共12页Seismology and Geology

基　　金：社会公益重点项目(2005DIA3J117);国家自然科学基金(40574019)

摘　　要：人工气枪震源在陆地水库可以有效激发S波,S波能量较强,与ML1.6天然地震相当。气枪可用于S波分裂研究,对布置在燕山隆起带的流动地震台的气枪信号进行了S波分裂参数分析,结果表明,快剪切波偏振优势方向为NWW和NNE向,偏振方向和断裂的性质密切相关。气枪是高度可重复性人工震源,利用气枪定点激发和定点接收有可能精确获取S波分裂参数随时间的变化规律,为地震预测探索实践提供可靠的物理途径。Shear wave splitting is a possible method for earthquake stress-forecasting. We applied shear wave splitting analysis to a seismic dataset generated by airguns in a reservoir. We found that the seis- mic data contains shear waves（Sg and SmS）. The shear waves are converted at the water-solid inter- face from P-waves generated by the airgun source, and the energy of the converted shear wave is equivalent to the energy released by a ME ｜. 6 earthquake. We analyzed the data recorded by a seis- mic line deployed over the Yanshan uplift. The results show that the predominant polarizations of the fast shear wave are in the directions of NWW and NEE, which are affected by the characteristics of the local fault system. Using an airgun as a repeatable seismic source and recording the data at a fixed point, the variation of shear wave splitting parameters can indicate the variation of local stress-strain fields, and hence provides a method for earthquake stress-forecasting.

关 键 词：气枪 人工震源 S波分裂 地震应力预测 

分 类 号：P315.3[天文地球—地震学]