Abstract: 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 seismic data contains shear waves(Sg and SmS).The shear waves are converted at the water-solid interface from P-waves generated by the airgun source,and the energy of the converted shear wave is equivalent to the energy released by a M_L 1.6 earthquake.We analyzed the data recorded by a seismic 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.

Key words: airgun, artificial source, shear wave splitting, earthquake stress-forecasting

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M_L1.6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。

关键词: 气枪, 人工震源, S波分裂, 地震应力预测