Study On The Interpretation Method Of Shallow Active Faults Seismic Reflection In Huairou Area

Active fault is the root of the earthquake, the shallow activity fault detection will play a big role to provide guidance for early warning and rescue work after the earthquake, it can protect the socio-economic and people’s property effectively. Seismic exploration methods are effective means of detecting underground geological structures, the interpretation as it’s ultimate step will directly determine the accuracy and precision. So the research on the interpretation methods of active fault is very necessary.This paper is systemic interpreted the seismic datas of six 2D seismic lines and two 3D seismic areas in Beijing Huairou. The study area covered with thick Quaternary sediment that composed mostly of loose layers, including clay layer, sand layer and gravel bed, wave impedance difference between the interface is small, and it has very intense absorption to the signal, this causes the seismic data has low signal-to-noise ratio problem and the effective wave energy is weak. In vertical the Quaternary strata composed different lithology thin interbed, Thickness is difficult to reach the limits of resolution of seismic interpretation. Active faults extend to the Quaternary layer and become more shallow. Relative to the reflection seismic exploration method, the fault throw is smaller, the breakpoint is too unclear to identify it in the seismic reflection profile, it’s more difficult to interpret active faults from the seismic data, so it need to compare the suitable methods for this study area.Considering the Geology and Seismic characteristics of datas for the study area, firstly we use regional geological and other geophysical methods of detection results of the study area to establish a geological model, and then we select the 3D seismic data interpretation,3D visualization technology, attributes analysis technology, coherent technology and refraction tomography method on two 3D seismic work area shallow active faults to interpret. As the quality of North refraction data is better, so we use refraction tomography and 3D seismic interpretation techniques, combined with 2D seismic data interpretation, we identify the Huangzhuang-Gaoliying fracture and its characteristics and nature of a detailed analysis. To the Southern District, we use coherent technology to identify the Niulanshan fracture and extract a variety of attributes, and make a comprehensive analysis to identify the existence of Niulanshan and Beixiaoying faults. With the Combination of coherent interpretation of the results of slices along the layer properties and two-dimensional seismic data to interpret the results, a detailed analysis of Niulanshan and Beixiaoying fracture and fracture characteristics of horizontal distribution and profile characteristics. The combination of North and South in the interpretation of results, we obtained a set of seismic interpretation methods of the shallow seismic geological characteristics of the study area of active faults.