No abstract

No abstract

As revealed by field investigations, the co-seismic surface rupture zone of the 2010 M S 7.1 Yushu earthquake, Qinghai is a characteristic sinistral strike-slip feature consisting of three distinct sinistral primary ruptures, with an overall strike of 310°-320° and a total length of 31 km. In addition, an approximately 2-km-long en-echelon tensile fissure zone was found east of Longbao Town; if this site is taken as the north end of the rupture zone, then the rupture had a total length of ~51 km. The surface rupture zone is composed of a series of fissures arranged in an en-echelon or alternating relationship between compressive bulges and tensile fissures, with a measured maximum horizontal displacement of 1.8 m. The surface rupture zone extends along the mapped Garzê-Yushu Fault, which implicates it as the seismogenic fault for this earthquake. Historically, a few earthquakes with a magnitude of about 7 have occurred along the fault, and additionally traces of paleoearthquakes are evident that characterize the short-period recurrence interval of large earthquakes here. Similar to the seismogenic process of the 2008 Wenchuan earthquake, the Yushu earthquake is also due to the stress accumulation and release on the block boundaries resulting from the eastward expansion of Qinghai-Tibet Plateau. However, in contrast with the Wenchuan earthquake, the Yushu earthquake had a sinistral strike-slip mechanism resulting from the uneven eastward extrusion of the Baryan Har and Sichuan-Yunnan fault blocks. M S 7.1 Yushu earthquake, surface rupture, large historical earthquakes, Garzê-Yushu Fault Citation: Chen L C, Wang H, Ran Y K, et al. The M S 7.1 Yushu earthquake surface rupture and large historical earthquakes on the Garzê-Yushu Fault. At 7 : 49 on April 14, 2010, an M s 7.1 earthquake occurred in Yushu County, Yushu Tibetan Autonomous Prefecture, Qinghai Province, China. The earthquake left more than 2200 people dead and destroyed more than 80% of the buildings in Jiegu Town. It was one of the largest earthquakes experienced in the region since the 2008 M s 8.0 Wenchuan earthquake, causing huge losses of life and property in China. The seismotectonic setting and earthquake surface rupture characteristics for this earthquake and the recurrence pattern of major earthquakes on the seismogenic faults in this area are major concerns of community and a focus of research activity. *Corresponding author (email: ykran@263.net)The investigation and discussion of such issues as soon as possible after an earthquake occurs can provide important reference information for post-earthquake reconstruction and delineate key surveillance and protection regimes for future large earthquakes. Based on the first field survey to be conducted in the area after the earthquake, we aim to depict the co-seismic surface ruptures of the Yushu earthquake and to analyze the seismogenic structures and earthquake recurrence characteristics in combination with historical earthquake records and paleoseismology surveys.

No abstract

The amount of coseismic deformation and its distribution of the Wenchuan earthquake provide important scientific bases for revealing the mechanisms of earthquake preparation and characterizing the rupture propagation of the Wenchuan earthquake. The previous studies have indicated that the earthquake ruptured the middle-to-north segment of the Longmenshan central fault and the middle segment of the Longmenshan range-front fault, which are characterized by two surface rupture zones of 240 km and 90 km in length, respectively. Based on the pre-earthquake information and photos of landforms and buildings obtained through geologic and geomorphic survey of the area around Shaba Village of Beichuan County, Sichuan Province and the extensive interview with local villagers, we measured the displacements of the major terrain features and the dislocated buildings by total station instruments and differential GPS and obtained the maximum vertical displacement of 9±0.5 m and right-lateral displacement of 2±0.5 m around the Zou's house in Shaba Village. Though the near-surface deformation exhibits a normal faulting around Shaba Village, the dynamic environment has not changed on the whole. The NW wall of the fault uplifted but without gravity gliding as normally occurring on the hanging wall of a normal fault, which proves that the 9±0.5 m displacement should be the maximum coseismic vertical displacement of the May 12, 2008 Ms 8.0 Wenchuan earthquake. Wenchuan earthquake, Shaba Village in Beichuan County, maximum coseismic displacement, deformation pattern Citation: Ran Y K, Shi X, Wang H, et al. The maximum coseismic vertical surface displacement and surface deformation pattern accompanying the Ms 8.0 Wenchuan earthquake.The coseismic deformation amount and its distribution will provide significant scientific bases for understanding the dynamics and kinematics of the eastern border of Tibetan Plateau, revealing the mechanism of earthquake preparation and rupture propagation of the Wenchuan earthquake, and planning for post-earthquake reconstruction. Extensive investigation and study were conducted after the Wenchuan earthquake on the coseismic deformation amounts and their distribution by geo-scientists from various aspects, e.g. ground surface survey over about 1000 observation sites in particular, and abundant observation data were achieved [1-15] (http:// www.csi.ac.cn/sichuan/henyuntai.pdf).The main knowledge about the earthquake includes: two surface rupture zones accompanying the Wenchuan earthquake were generated along the central to north segment of the NE-trending central Longmenshan fault and the middle segment of the range-front fault of Longmenshan, respectively, of which, the master surface rupture zone along the central fault is about 240 km long, and its northmost part departs from the central fault and extends along a NE-trending sub-fault between the central fault and the Qingchuan fault. The surface rupture zone along the range-front fault of the Longmen Mountain is about 90 km