FMTT方法研究华北及邻区上地幔P波速度结构

本文利用华北地震科学台阵190套宽频带地震仪在2006年10月至2009年3月记录的远震事件,采用波形互相关技术提取了52414条P波初动到时数据,进一步使用FMTT(Fast Marching Teleseismic Tomography)方法,获取了华北克拉通中、东部陆块下方上地幔分辨高达0.5°×0.5°的P波速...

The P wave velocity structure of upper mantle beneath the North China and surrounding regions from FMTT

In this study we used 52414 P wave first motion traveltimes to get the P wave velocity structure of upper mantle beneath the Central Block (CB) and Eastern Block (EB) of North China Craton (NCC) by Fast Marching Teleseismic Tomography (FMTT). There were 190 broadband stations from North China Seismic Array, and all of the teleseismic events occurred during Oct. 2006 and Mar. 2009. The relative traveltime residuals were got by waveform cross correlation. The checkerboard resolution was ~0.5°×0.5°. The results reveal that: an obvious low-velocity anomaly is located at the region beneath the CB and EB of NCC, which extends from 40 km to 240 km; but beneath the Yanshan Uplift region, there is a high-velocity zone. These show that the CB and EB of the NCC have been obviously destructed, but the destruction region does not include the Yanshan Uplift; or the destruction of CB and EB is more apparent than that of Yanshan Uplift. The low-velocity anomaly extends to ~250 km depth beneath the CB of NCC, which may have something to do with the formation of Cenozoic pyrogenic rock and Fenwei valley graben.