Inferred Seismic Fault Associated with the 1998 M = 6.2 Zhangbei-Shanyi Earthquake, Hebei Province, China

Abstract The shallow, Ms = 6.2, 1998 Zhangbei-Shanyi earthquake that affected the northwest region of Beijing, China, occurred at the intersection of two active fault zones, located on the north and east edges of the Ordos tableland. A detailed map of the intensity distribution of damaged building shows that the most damaged area was centered 8 to 10 km away from the epicenter, including an ellipsoidal region with a strike of NNE, where more than 70 to 90% of buildings were destroyed. Many chimneys and gate pillars were broken and fell toward the SSE-SSW direction in the western side of the most damaged area and to the NNE-NNW direction in the eastern side. Aftershocks were also concentrated in the most damaged area. It is inferred that the boundary of the downfallen direction change is the surface trace of the seismic fault. Based on the seismic data, the distribution of damaged buildings, and the downfallen directions of 70 chimneys and gate pillars, it is identified that the seismic fault is a thrust fault striking NNE and dipping 40° to 50° northwest with a large right-lateral displacement component.