基于气枪震源信号和背景噪声的2016年呼图壁6.2级地震前后波速变化特征初步研究

A Preliminary Study on the Characteristics of Wave-Velocity Variation before and after the 2016 Hutubi M6.2 Earthquake Based onAir-Gun Source Signals and Background Noise

摘要:

本文选取呼图壁气枪发射台周边流动台记录的2016年6月至2017年12月气枪震源信号和背景噪声信号，分别采用互相关时延检测法和移动窗互谱法研究2016年12月呼图壁6.2级地震前后波速变化特征，得到以下初步结果：呼图壁6.2级地震前后，距6.2级地震60 km的流动台记录的气枪震源信号未发现明显的波速变化，距6.2级地震27 km的固定台石梯子台在6.2级地震前出现了较为明显的波速变化异常，可能与信号传播路径不同有关；流动台记录到的背景噪声信号出现与呼图壁6.2级地震有关的波速异常变化；气枪主要利用体波信号，背景噪声主要利用面波信号，两者射线路径不同可能是导致不同波速变化特征的主要原因。

Abstract:

In this study, we analyzed the air-gun source and background noise signals recorded by mobile stations around the Hutubi air-gun launching station from June 2016 to December 2017. To study the wave-velocity characteristics before and after the Hutubi M6.2 earthquake in December 2016, we used the cross-correlation time-delay detection method and the moving window cross-spectrum method, respectively. The preliminary results are as follows:(1) before and after the Hutubi M6.2 earthquake, the air-gun source signals recorded by the mobile stations showed no obvious wave-velocity changes, whereas the fixed Shitizi station (27 km away from the earthquake) showed obvious wave-velocity anomalies prior to the M6.2 earthquake, which may be related to different signal propagation paths; (2) the background noise signals recorded by mobile stations caused abnormal variation in the wave velocity, which was related to the Hutubi M6.2 earthquake; and (3) air guns mainly emit body wave signals and background noise mainly occurs as surface wave signals. Their different ray paths may be the main reason for the different wave-velocity characteristics.