陕西地区地壳厚度初探

A PRELIMINARY STUDY ON THE CRUSTAL THICKNESS IN SHANXI REGION

摘要:

本文利用陕西测震台网记录到的七次人工爆破与邻区10个中强地震资料,利用由莫霍界面的首波P_n的走时数据,采用改进的时间项法^[1]相对时间项法^[3][4]计算了各测点的时间项b_j和v_pn,最后得出40个测点的地壳厚度。陕西地区地壳厚度的总趋势是东面较薄,西面较厚。陕北地壳较厚,约为41~43公里,陕南秦岭断块地区地壳厚度约为40公里,而渭河盆地地壳较薄,平均约为36公里。研究结果表明,地壳深部结构与地震活动存在着一定的联系。

Abstract:

From the data of 7 artificial explosions and 10 moderate strong earthquakes of nearby regions recorded by the Shaanxi Seismic Network and also the data of head wave pn from Moho, the time-term bi and vpn for each observation spot and the crustal thickness beneath 40 observation sots are determined by use of the improved time-term method[1] and relative time-term method[3],[4]. Generally speaking, the crustal thickness in Shaanxi region is thinner in the east and thicker in the west. The crust in northern Shaanxi is relatively thick, about 41-43kin. For faulted regions in the Qinling Mountains, it is about 40 kin. The crust in the weihe Basin is relatively thin, about 36 km on ae average. The results suggest that there exist a certain relation between deep crustal structure and seismic activity.