Seismic reflection exploration is the main method of detecting urban active faults at present.The effect of investigating fault is fairly satisfactory in areas with thick Quaternary sediments.Detecting active faults by the seismic method is more difficult because of a-dopting shorter receive array length,more serious source disturbance to shallow reflection interference,and requiring higher resolution in urban shallow Quaternary sediment areas.Geziwo fault in Beidaihe is part of Qinhuangdao-Dalian fault on land.Because the fault is a hidden fault,the dip,fault distance and upper break point as well as spatial distribution of the fault all show uncertainty. In order to find out the spatial distribution shape,nature and activity of the fault,the author detected the fault by shallow seismic exploration technology with high precision,with the obtaining of a very clear reflection seismic image.The Quaternary internal interface,bedrock and bedrock weathering layer as well as fracture structure can be explained on the basis of the seismic profiles.The seismic detecting result provides the basis for the layout of the drilling joint section,the design of borehole depth and the evaluation of the fault activity.The high-preci-sion combined drilling geological sections show that the main stratigraphic boundaries and fault features obtained from the seismic explo-ration methods are quite consistent with the results from the composite drilling geological section.%反射地震方法是当前探测城市地震活断层的主要方法,该方法在厚覆盖区探测效果较好.在浅覆盖区采用的接收排列长度较短,震源干扰波对浅层反射波干扰严重,且要求的分别率较高,应用反射地震方法探测城市活断层难度较大.北戴河鸽子窝断裂是秦皇岛—大连断裂在陆地上的一部分.由于该断裂为隐伏断裂,对断裂的倾向、断距、上断点和空间展布存在不确定性.为查明该断裂的空间展布形态、性质以及活动性,采用高精度浅层地震探测技术探测该断裂获得了十分清晰的反射地震图像,依据该地震剖面能够对第四系内部界面、基岩和基岩风化层及断裂构造进行解释,为钻孔联合剖面位置的布设、钻孔深度的设计以及断裂活动性的评价提供了依据.最后经高精度钻孔联合地质剖面证实,地震勘探方法反演得到的主要地层界面和断裂构造特征与钻孔联合地质剖面吻合较好.
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