利用接收函数研究龙门山断裂带及邻区地壳厚度(H)和波速比(K)

Abstract

对龙门山断裂带及其邻近地区27个地震台站的记录提取远震P波接收函数，并应用H-K叠加方法，求得每个台站下方的地壳厚度和波速比。研究区域地壳厚度总体变化是，从东往西地壳增厚。扬子地块地壳厚度变化较为平缓，厚度在41~48 km之间；龙门山断裂带南北段地壳厚度存在差异，南段比北段厚3~9 km；松潘–甘孜地块地壳较厚且变化剧烈，深度在49 km以上，且在东西方向上呈“凸”形展布；研究区波速比变化范围在1.68~1.88之间，其中汶川、井研和石棉地区波速比较高。 Using teleseismic data recorded at 27 seismic stations in the region along and surrounding the Longmenshan fault zone, the P-wave receiver function were computed, and the crustal thicknesses and wave-velocity ratio were estimated by the H-K stacking method. The crustal thickness increases from east to west in the study area. The thickness of the crust of the Yangtze block is relatively flat, and the thickness is between 41 and 48 km. There is a difference of crustal thickness between north and south part of the Longmenshan fault, and the south part is deeper than the north about 3 - 9 km. The crust of Songpan Ganzi block is thicker and increases sharply. The depth is more than 49 km and it’s a convex distribution from east to west. In the study area, the wave velocity is between 1.68 and 1.88, and wave-velocity ratio values in Wenchuan, Jingyan and Shimian is higher.