Study on the Relationship between Paleoseismic on Laji Mountain Fault and Catastrophic Event on Lajiashan Site

The geometric features of the Lajishan Fault Zone are got by remote sensing data in high resolution.According to the field investigation and excavation trenches,we do the research of paleoseismics on Laji M ountain Fault.The result obtained as follow: The fault scarps were formed in stage terrace of YellowRiver,because of the thrusting activity of Lajishan Fault in the Dajiahe Region.Through the excavation trenches on the location of scarps,there were at least two medium-strong paleoseismic in the study region,which made the stage terrace of YellowRiver formed.The last paleoseismic occurred on about( 3 136 ± 51) a.BP,the slip rate along Lajishan Fault Zone is estimated to be about 0.51 mm / a since late Holocene.The Lajia site which formed in about 3650~ 2750 a BP is 6.4 km far from the trench profiles,so the strong paleoseismic on Lajishan M ountain Fault Zone is closely related to the destroy of Lajia culture.The research has the important scientific value to recognize the seismic risk of Lajishan M ountain Fault Zone and determine the paleoseismic evidence of forming the Lajia site.