Study on Medium- and Long-term Strong Earthquake Risk Along the Zhangjiakou-Penglai Fault Zone

The Zhangjiakou-Penglai fault zone lies in the northern part of North China Plain and extends along the Zhangjiakou-Huailai-Sanhe-Tianjin-Bohai Sea-Penglai-Yantai-North Huanghai Sealine,it is about 900km long and some 250-km kide in a northwest direction.The 1679 SanhePinggu M8.0 and the 1976 Tangshan M7.8 earthquakes occurred in the fault zone.In this paper an analysis of Gutenberg-Richter's empirical relation and time process of historic and recent earthquakes along the eastern and western segments of the fault zone separated by the 117°Eline indicates that they obey a Poison process and ,hence,a calculation from it yields a cumulative probability of strong earthquake occurrence along the two segments before 2010,i.e.the probabiltiy of M6.0 earthquake occurrence is 0.80 along the eastern segnment and the probability of M7.0 earthquake occurrence is 0.76 along the western segment of the fault zone.