The Zhaotong-Ludian Fault zone, composed mainly of three right-step en echelon faults, namely, the Zhaotong-Ludian Fault, the Sayuhe Fault and the Longshu Fault, strikes 40°～60° on the whole, with the Sayuhe Fault and the Longshu Fault dipping SE and the Zhaotong-Ludian Fault dipping NW, and they all together constitute a complicated thrust fault system. Based on years of field investigation results of geology and geomorphography, we elaborate the late Quaternary active features, the geological and geomorphic evidences of the latest activity of the Zhaotong-Ludian Faults. Our observation shows that: the late Cenozoic basins along the Zhaotong-Luian Fault zone are obviously dominated by the fault; there are many neo-active fault landforms, such as, flat and straight fault troughs, directional aligned fault facets and fault scarps, and the upper Pleistocene to Holocene strata are offset by the fault. The fault zone has been active since the late Quaternary. For example, the fault at Daqiaobian dislocated a set of strata of the Pliocene, and middle to upper Pleistocene, with an apparently reverse character. The fault trending NE is developed in the Holocene diluvium with oblique striation on the fault plane at Guangming Village. Deposits with an OSL age of(23.4±1.8)ka BP on T2 terrace of a small river near Beizha town was offset by the fault. There is a fault scarp trending NE 40°, 0.5～2.0m in height, on the first terrace of the Longshu River near the Longshu Village. Several Quaternary faults are revealed by the trench which offset the late Pleistocene to Holocene strata and there are three poleo-earthquake events discovered in the trench. At Yanjiao Village the gravel layer has risen steeply and is aligned in a line because of squeezing effect of the fault; the rivers and ridges nearby are synchronously offset dextrally up to 30～40m. The fault zone is dominated by reverse faulting with a small amount of right-lateral motion. Besides, there are some NW-trending faults interweaving with the NE-trending fault zone, some of which are active since late Quaternary as well, and they are the conjugate structures with the NE-trending faults. Surface deformation, such as NE- and NW-trending ground fissures and reverse scarp landforms, has been generated in the epicenter area of the 2014 Ludian M6.5 earthquake, the distribution of which is in consistence with the NE- and NW-trending faults. Because of far-field deformation response and energy exchange and transfer between blocks, the Liangshan active sub-block formed on the east of the Sichuan-Yunnan block, and the Zhaotong-Ludian Fault zone lies in the forefront of the SE movement of this sub-block. On account of its distinct location and its complicated geometric structure, the Zhaotong-Ludian Fault zone is one of main carriers of the tectonic deformation of the Liangshan active sub-block to absorb and accommodate the strains produced by the block's SE movement, and is the southern boundary of the Liangshan sub-block. From the point of view of the regional tectonic positions and the kinematic characteristics, the relation of Zhaotong-Ludian Fault zone to the Liangshan active sub-block is exactly as the relation of the Longmanshan Faults to Bayan Har block. Consequently, the Zhaotong-Ludian Fault zone has an important significance in the division of active block boundaries and the regional tectonic framework, and meanwhile, it is also an important seismogenic structure in the northeastern Yunnan.

There are numerous Late Quaternary active faults in Dari area, Qinghai Province, with the major strike orientation of NW-NWW and SN. Through analyzing of satellite images and field investigation, we observed significant new activity of the middle segment of Dari Fault during Late Quaternary. The Dari Fault locates in the south of Qinghai Province, and it's a left-lateral strike-slip active fault. Along the studied segment, the surface rupture zones of the M7 (3/4) earthquake are still preserved. The rupture styles of the M7 (3/4) earthquake surface rupture zones are varied and diversified in different segments. This feature is represented by changes of local tectonic stress. The Dari area, as a typical active tectonic zone, is ideal for studying the neotectonics and the geomorphological responses. So in this paper, we also discussed the relationship between the tectonic activities and its geomorphological response in the study area. Analysis on ASTER GDEM V2 digital data enabled us to extract the sub-basins and rivers in this region, and finally determine the hypsometric curves and hypsometric integral(HI values)of the sub-basins. Hypsometry is adopted to analyze the evolution processes of six sub-basins of the Yellow River in the study area. The results show that the geomorphological evolution of the six sub-basins is in the stage of maturity, and the evolution process is highly synchronized, indicating the overall result of regional tectonic uplift or subsidence. Furthermore, the distribution characteristics of the hypsometric integrals(HI value)of the sub-basins reveal that the location of low HI value areas coinsides with the distribution of Quaternary graben basins and valleys, reflecting the results of different local tectonic subsidence and erosion. On the other hand, the high HI areas mainly occur where the strike of the Dari earthquake surface rupture zone changes from NWW to NW and where Early Jurassic and Late Triassic granodiorites are distributed, indicating clearly the variation of local tectonics and difference in lithology.

Field investigations show that the M_S8.0 Wenchuan earthquake of 12^th May 2008 ruptured two NW-dipping imbricate reverse faults along the Longmenshan Fault zone at the eastern margin of the Tibetan Plateau.This earthquake generated a 240km long surface rupture along the Beichuan-Yingxiu Fault characterized by right-lateral oblique faulting and a 90km long surface rupture along the Guanxian-Jiangyou Fault characterized by dip-slip reverse faulting.Maximum vertical and horizontal dispacements of 6.2m and 4.9m,respectively,were observed along the Beichuan-Yingxiu Fault,whereas a maximum vertical displacement of 3.5m occurred along the Guanxian-jiangyou Fault.This co-seismic surface rupture pattern,involving multiple structures,is among the most complicated of recent great earthquakes.Its surface rupture length is the longest among the co-seismic surface rupture zones for reverse faulting events ever reported.Aftershocks recorded by local network clearly outline the hanging wall of the Beichuan-Yingxiu Fault and indicate that the fault dips about 47? to the west.Industry seismic lines,in addition to surface ruptures and aftershocks,allow us to build a 3D model for the rupture geometry that shows crustal shortening is the dominant process along the Longmen Shan to accommodate long-term deformation.Oblique thrusting accomplished by the earthquake indicates that the east-southeastward extrusion of Tibet Plateau accommodates,in part,the continuing penetration of the Indian plate into the Eurasian plate,and this extrusion is transformed at the eastern margin of the Tibetan Plateau into crustal thickening and shortening along the Longmenshan Fault zone that is responsible for the growth of high topography in the region.

The Longmenshan Fault zone,trending in NE,lies between the Songpan-Ganzi orogenic belt and the Yangzi block.It consists of four major faults,such as the Houshan Fault,and related thrusting sheets.It is a nappe structure characterized by forward spreading.It formed during the Indo-China movement and was active many times since then.Since the Quaternary,this fault zone has been very active,and exhibits differential activity on its various sections.In this work,we make an integrated analysis of this fault zone based on data of geomorphology,geology,Bouguer gravity anomalies,and earthquakes.The results show that the near NS-striking Leidong Fault,located along Beichuan-Anxian,is the boundary between the middle and northeastern sections of the Longmenshan Fault zone.The two sections have high distinctive activity.The middle section is very active since late Pleistocene time with frequent medium-and small-sized earthquakes,while the northeastern section has weak activity since Quaternary with occasional small earthquakes.Due to the compression and uplift of the Tibetan Plateau and lateral sliding of blocks,the Sichuan-Qinghai block moves towards SEE,resulting in an active boundary of the block.This boundary includes the Mingshan uplift and the middle and southwestern sections of the Longmenshan Fault zone,both of which are truncated by the Mingshan uplift.And the northeastern section of the Longmenshan Fault zone has been abandoned.

The Litang-Batang region of western Sichuan Province is located at the eastern section of the Tibet Plateau. Since the Late-Cenozoic,the East Tibet Block has thrust over the Sichuan-Yunnan Block from west to east along the NS-trending Jinshajiang Fault zone,resulting in the nappe tectonic belt of 30 km width accompanied by the formation of the NNE-trending Batang Fault and the NW-trending Litang Fault,a pair of conjugate shear faults. In the vicinity of Daoxu,south of Derenduo,the generally NS-trending Jinshajiang Fault zone extends along NNW direction and displaces left-laterally a series of gullies for about 120～140m. At south of Yarigong,the fault extends along NNE direction and dislocates right-laterally a series of gullies for about 180～210m. In contrast,no evidence of horizontal displacement is observed on the NS-trending segment of the fault. It is suggested,therefore,that the Jinshajiang Fault zone should be characterized by shortening in nearly EW direction. Based on the results of GPS measurement,the shortening rate is determined to be about 2～3mm/yr. The NW-trending Litang Fault is dominated mainly by left-lateral shear movement. According to the dislocation value and the initiation time of dislocation obtained at southeast of Kangga,southeast of Litang and northwest of Heni etc,the average horizontal slip rate on the Litang Fault is estimated to be 3.2～4.4mm/yr on the Litang-Dewu segment,and 2.6～3.0mm/yr on the segment to the north of Litang. The NNE-trending Batang Fault cuts obliquely the main part of the Jinshajiang tectonic zone,displaying mainly right-lateral shear movement. At Mangling Village of Markam County,Tibet,the average horizontal slip rate on the fault is estimated as 2.0～2.7mm/yr,wiile in the vicinity of Batang it is estimated to be 1.3～1.9mm/yr. The connecting line of the eqicenters of the 1989 Batang M 6.7 earthquake swarm and the long-axis of the aftershock distribution all extend nearly along EW direction,and the focal mechanism solution indicates an EW-trending normal faulting. Therefore,we tend to believe that the NNE-trending Batang Fault and the NW-trending Litang Fault to be a pair of conjugate shear ruptures. The southern block between these two faults slips southwards,resulting in EW-trending normal fault at the intersection of the two faults. It was the tensile rupturing on the normal fault that induced the Batang M 6.7 earthquake swarm,as evidenced by the development of EW-trending normal faults on the southern edge of the Maoya basin and the nearly EW-trending surface rupture of about 2 km in length produced by the Batang M 6.7 earthquake swarm.