Study of Paleoearthquakes by Excavation of Grouped Trenches on the Zemuhe Fault in Daqingliangzi,Xichang,Sichuan

Uncertainties are common in the dating of paleoearthquakes. To improve the credibility of the dating of paleoearthquakes, analysis was done on fault activity, sedimentary environment and seismo-geomorphology to investigate paleoearthquakes along the Zemuhe active fault zone. Grouped trenches were excavated near Daqingliangzi, which revealed three palaeoearthquake events aged 160a, 3100a and 5500a～8900a, respectively, including recurrence intervals of about 3000a. Sedimentary processes related to strike-slip fault type earthquakes were discussed, and a sedimentary model was put forward for strike-slip faults at hillsides where drumlin and reverse scarp developed.