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近期完成的近东西向的北京—怀来—丰镇宽角反射／折射剖面斜穿北西向的张家口—渤海地震带，并在延怀盆地与一条深反射剖面重合，其目的是探测研究延怀盆地及外围地区的地壳上地幔构造、速度分布及其与地震活动的关系．结果表明：地壳呈层状结构，地壳厚度由顺义的３５．０ｋｍ向西逐渐加厚至４２．０ｋｍ；壳内界面近于水平或由东向西缓倾；在延怀盆地地壳呈高低速相间的特征．上地壳的下部存在明显的低速体，并有两条地壳深断裂带延伸至莫霍面，这与延怀地区地震活动密切相关．
The recently completed near east-west Beijing-Huilai-Fengzhen wide-angle seismic reflection / refraction profile obliquely traverses the NW-trending Zhangjiakou-Bohai seismic zone and overlaps a deep-reflection profile in the Yanhuai Basin with the purpose of exploring and researching Yanhuai THE STRUCTURE AND VELOCITY DISTRIBUTION OF THE CRUST AND THE UPPER MANTLE IN THE BASIN AND THE PERIPHERAL AREA AND ITS RELATION TO SEISMICITY. The results show that the crust has a layered structure and the thickness of the crust thickens gradually from 35.0km in Shunyi to 42.0km in the west; the in-shell interface is near horizontal or easterly to the east; in the Yanhuai Basin, Characteristics. There is a clear low-velocity body in the lower part of the upper crust, and two deep crustal faults extend to the Moho, which is closely related to the seismic activity in Yanhuai area.