关键词: 三河－平谷地震, 古地震, 地震复发周期

Abstract: The 4 paleoearthquake events that have occurred on seismogenic fault of 1679 Sanhe Pinggu M8 Earthquake since 20ka B.P. are exposed through the analysis of trenches and fault scarp profiles. The earlier two events are marked by liquefaction and the later two events are shown by direct fault offset,including the 1679 event. The 1679 event and pre 1679 event are two characteristic earthquakes of which the maximum displacement is about 1.75m and 1.41m,respectively and the intensity of two events is very close. The occurrence time of 4 events was about 20000,13000,7500 and 317a B.P.,respectively. Average interval of recurrence is (6561?691)a. It indicates the characteristics of quasi- periodic occurrence of earthquakes.

Key words: Sanhe-Pinggu earthquke, Paeoearthqake, Earthquake recurrence interval