Co-seismic surface rupture of 2010 Yushu earthquake (Ms7.1), Qinghai, China and its correlation with mountain uplift

In field investigation we found that Qinghai Yushu Ms7.1 earthquake occurred on April 14, 2010 produced a ~65 km long co-seismic surface rupture zone which strikes 310° and dips NE. The entire zone is composed of two parts: the west section is about 19 km long and the east section is 30 km. Between these two sections, a 15 km long zone surface rupture gap is observed. Surface ruptures displayed common sinistral lines mainly featuring right stepping en-echelon ruptures, while vertical offsets developed. The ratios between co-seismic vertical offset and horizontal offset range from 0.13 to 0.53, while the geomorphic dv/dh values of 0.27~0.63 are close to co-seismic dv/dh (0.13~0.53), indicating that the Yushu Nanshan uplift probably showed the same kinematic and dynamic characteristics. In other words, the Yushu Nanshan uplift is resulting from the cumulative vertical offsets produced by many earthquakes similar to Yushu earthquake along Yushu fault in the geological history. We conclude that we need 1800~2600 earthquakes similar to Yushu earthquake to form Yushu Nanshan. Former researchers reckon the recurrence period of the Yushu section of Ganzi-Yushu fault zone to be 120-200 years, which would make us believe that this fault section's activity started from 200~400 ka ago.