Abstract: In this paper, the method to reconstruct 3-D crustal interfaces using traveltime of wide-angle reflected waves is presented. We have treated the PmP reflected wave data from deep seismic sounding profiles carried out during recent years in North China using this technique, and obtained the 3-D Moho structure of this region. The spatial distribution of deep faults in the crust are determined. The results show that the depth of Moho increases from SE to NW in general and presents undulation on this background. The rift basins corresponds to the upper mantle uplift. In the study area, some deep crustal faults extend to Moho, one of which is the NE⁴/trending crustal thickness abrupt variation belt and the other is the NWW-trending crustal thickness variation belt, which are two main deep structural belts. In combination with the distribution feature of strong and moderate earthquakes in the region, the structure background of seismic activities is also discussed.

Key words: North China region, Moho discontinuity, 3-D structure

摘要： 给出了利用反射波走时重建地壳三维界面的方法,并处理了华北地区人工地震测深测线网中的PmP走时资料,获得了研究区莫霍界面的三维构造形态,确定了壳内深断裂的展布。结果表明,研究区莫霍界面埋深整体上由东南向西北加深,并在这一背景之上呈现波浪起伏,断陷盆地对应上地幔的隆起;区内存在数条延伸至莫霍面的地壳深断裂,其中大致沿北东走向展布的地壳厚度陡变带和沿北西西向的地壳厚度变异带是区内两条主要的深部构造带。将研究结果与本区中、强地震空间分布特征相结合,揭示了地震活动的深部构造背景。

关键词: 华北, 莫霍间断面, 三维构造形态