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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.

Following the Lushan M S 7.0 earthquake on 20 April 2013, a topic of much concern is whether events of M S 7 or greater could occur again on the southern segment of the Longmenshan fault zone. In providing evidence to answer this question, this work analyzes the tectonic relationship between the Lushan event and the 2008 Wenchuan earthquake and the rupture history of the southern segment of the Longmenshan fault zone, through field investigations of active tectonics and paleoearthquake research, and our preliminary conclusions are as follows. The activity of the southern segment of the Longmenshan fault zone is much different to that of its central section, and the late Quaternary activity has propagated forward to the basin in the east. The seismogenic structure of the 2008 Wenchuan earthquake is the central-fore-range fault system, whereas that of the 2013 Lushan event is attributed to the fore-range-range-front fault system, rather than the central fault. The southern segment of the Longmenshan fault zone becomes wider towards the south with an increasing number of secondary faults, of which the individual faults exhibit much weaker surface activity. Therefore, this section is not as capable of generating a major earthquake as is the central segment. It is most likely that the 2013 earthquake fills the seismic gap around Lushan on the southern segment of the Longmenshan fault zone.

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Geomorphic study on Wujiahe segment of Serteng piedmont fault, Inner Mongolia is made. Through analysis of the available data in combination with the results of predecessors' studies it can be obtained that average vertical displacement rate is 0.48-0.75 mm/a along the Wujiahe segment since the late Pleistocene (14.450~22.340 ka BP) and 0.56--0.88 mm/a since the early-middle Holocene (5.570--8.830 ka BP). Analyzing paleoseismic phenomena revealed in the excavated 5 trenches in combination with the results of predecessors' studies of paleoearthquakes on the fault, we determine five paleoseismic events on the Wujiahe segment of Serteng piedmont fault since 27.0 ka BP and the recurrence interval to be about 4.300~4.400 ka. A cluster of paleoearthquakes occurred probably during 8.000-9.000 ka BP and two paleoseismic events in 10.000-20.000 ka BP may be missed. A comparison between height of fault scarps and sum of displacement caused by paleoseismic events revealed in trenches, and recurrence interval of paleoseismic events obtained from average displacement rate along the fault and the dislocation by one event suggest that three paleoseismic events are absent in Alagaitu trench. Two paleoseismic events may be absent on the whole active fault segment.

Late Quaternary rupture behavior of large earthquakes along the Yingxiu-Beichuan fault and the Longmen Shan fault zone has been the focus of geoscientists since the 2008 Wenchuan earthquake. However, most studies have concentrated on the southern segment of the fault from Yingxiu to Beichuan. Here we opened trenches and used borehole drilling in Guixi and Pingxi along the northern segment (north of Beichuan) with the following paleoseismic results: (1) Trenches at Pingxi and Guixi reveal that at least one paleoseismic event occurred prior to the 2008 Wenchuan earthquake with ages of 770-955 A.D. and 665-1030 A.D. determined at the two locations, respectively. This event is possibly associated with a historical earthquake documented from 16 November to 15 December of 942 A.D.; furthermore, the trench and boreholes at Guixi may reveal another paleoseismic event occurred at 8240-7785 B.C.; (2) the northern segment (north of Beichuan) of the seismogenic structure of the 2008 Wenchuan earthquake ruptured independently from the southern segment; specifically, the southern segment records three events within the past 6000 years, whereas the northern segment shows a different rupture behavior. We suggest that the Yingxiu-Beichuan fault can be divided into at least two rupture segments.

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

Decreasing deformation rates across the southern Tianshan have led to different seismogenic mechanisms and different proposed models to explain the orogen-scale fault kinematics. In this study, we focus on the segmentation of the Kepingtage fault by studying variations in the total offset and shortening rates of the Kepingtage fault along the southern front of the Tianshan. We used fault scarp mapping and trench excavations to assess fault segmentation and deformation on the Kepingtage fault. Our results indicate there are different shortening rates on the western (2.5-2.7 mm/year) versus the eastern segments (~ 0.3 mm/year), which are separated by the Piqiang tear fault. The decrease in shortening rates is not gradual; instead, it decreases sharply from west to east at the Piqiang fault. These segmentation boundaries are also supported by geodetic data and balanced structural restorations. Our data support a model where strike-slip faults accommodate step-changes in the deformation rates and the earthquake risks from west to east across the Tianshan.