利用深源近震高频Ps转换波震相研究松辽盆地沉积层结构

本文利用高频深源近震地震波形数据的R/Z比来获取沉积盆地速度结构,并以2011-05-10发生在黑龙江省与吉林省交界处(131.09°E,43.32°N)的M W5.7深源地震(深度554.9 km)为例,分析位于松辽盆地沉积层内部NECESSArray中的22个台站记录到的0.5~2 Hz数据,利用沉积盆地对地震波的到时延迟效应及P波和Ps转换波的振幅信息,通过对沉积盆地底部剪切波速度与厚度进行网格搜索获得松辽盆地的速度结构。结果显示,22个台站下方的沉积层顶部剪切波速度为0.1~1.0 km/s,且盆地边缘速度较大,盆地厚度为0~6.5 km,总体呈现内部大于边缘的状态。与已有结果相比,本文结果在沉积层边缘地带较符合实际趋势,表明利用高频近震深源Ps转换波的方法可以较好地获得沉积盆地内部的速度结构。

Sedimentary Structures of the Songliao Basin Using High-Frequency Ps Converted Wave from Local Deep Earthquakes

In this paper, we obtain waveforms from an M_W5.7 deep-source earthquake with a depth of 554.9 km that occurred at the junction of Heilongjiang province and Jilin province (131.09°E, 43.32°N) on May 10, 2011. We analyze high-frequency (0.5 to 2 Hz) radial and vertical data from 22 NECESSArray stations, which are located in the Songliao basin. Using the effect layer on travel-time delays, and amplitudes of the P wave and Ps converted waves, we obtain the shear velocities on the top and bottom of the sediment layer using a grid-search method. The results show that the shear velocity on the top of the sediments below 22 stations is 0.1 to 1.0 km/s. The thickness of the basin is 0 to 6.5 km. Our results obtained in this paper generally agree with other studies, with some discrepancies at the edge, indicating that velocity structures of the sedimentary basin can be obtained through high-frequency Ps converted wave from local deep-source waveform data.