关键词: 大地切片调查法, 三河-平谷8级地震, 古地震, 垂直同震位移

Abstract: Geo-slicer method,a newly developed technique for detecting active fault,is designed to take a slice of unconsolidated Quaternary strata whose texture and structure are not destroyed. The Sanhe-Pinggu M8 earthquake of 1679 is the biggest one recorded in Beijing area. The macroscopical epicenter is located around Pangezhuang Village,Xiadian Town,Hebei Province. We successfully applied the geo-slicer method to detecting the rupture of this earthquake near its epicenter. Through our test research,we gained the following knowledge: 1)the detailed deposit structure of the unconsolidated strata can be kept in the geo-slicer; 2)the power unit should be selected to fit to different site conditions,and for Beijing area,a power unit with "grab+vibrant hammer" is better than that with "crane+hammer" ; 3)there is some shortening due to the vibration of the power,but the shortening is generally less than 5%. Moreover,synthesizing the information from the geo-slicers and trench,we found two earthquake events. One is the 1679 earthquake and the other is the one before the 1679. The vertical seismic displacements are 1.4m and 1.2m,respectively.

Key words: geo-slicer, Sanhe-Pinggu earthquake, paleoearthquake, vertical seismic displacement