Imaging the active faults with ambient noise passive seismics and its application to characterize the Huangzhuang-Gaoliying fault in Beijing Area, northern China

Most serious geotechnical problems related to rock engineering are generated by the existence of faults. Detection of fault (especially active faults) is the first step to conduct any further in-depth studies in faulted rock mass or rock blocks. In this paper, we investigated the plausibility to image fault zones by passive seismic surveys using recorded ambient noise. The test site is in the north suburb of Beijing, northern China along the south bank of the northwest-southeast running Wenyuhe River, where the NNE-striking Huangzhuang-Gaoliying fault (HGF, active in the Holocene) is crossing. In general, the results are in good agreement with previous studies using active source seismics conducted in this area along the HGF and existing borehole drillings in the vicinity. Undoubtedly, Active source seismic reflection technique is the best technique to image fault in depth with high resolution. The drawback is its high cost and the necessity of using explosives, a practice usually prohibited in urban settings. In contrast, passive seismic surveys take the advantage of the ever-existing ambient noise source, and provide a low-cost technique, and fast deployment that can locate the fault effectively. Though the imaging resolution is lower compared to those obtained by active source seismic surveys, our passive seismic experiment at the Wenyuhe River site demonstrated that this approach is effective, especially for those faults with significant normal faulting component and the stratigraphy is significantly different on the two sides crossing the fault line.