A tentative discussion on the seismic and geological significance of the seismic rockfall along the Yushu faulted zone in Qinghai Province

In 2010, Ms 7.1 earthquake in Yushu ,Qinghai Province triggered a series of secondary geological disasters, in addition to the earthquake landslide, distribution of seismic rock fall along the fault zone and its adjacent side is extremely common. By the investigation of rockfalls in Yushu area, the survey indicated in a number of typical rockfall zone, in addition to the fresh rockfalls formed in the 2010 earthquake, there are still a lot of early seismic rockfalls scattered, which suggests that the development of seismic rockfall is similar to paleo-earthquake activity, with multi-period and a certain number of in-situ recurrent. The typical seismic rockfall survey found that the distribution characteristics of rockfall is mainly: general concentrated distribution below steep rock slopes near the active fault belt, scattered distribution, rolling far away, and often accompanied by paleo-earthquake landslide.Preliminary U series dating result of 8 seismic rockfalls calcium membrane, distributed in 6030±300a BP, 4720±210a BP, 3530±490~3560±280a BP, 2010±160a BP, 1090±70a BP,760±20a BP and 230±20a BP before present, this result tallies with the seismic events reflected by paleo-earthquake trench and paleo-earthquake landslide well, further reveals the Yushu fault zone occurred multi-period events in the Holocene middle-late leading to the surfacial seismic rockfalls. It also shows that seismic rock fall and calcium membrane dating is a potential and especially worthy way to further explore for the paleo-earthquake research.