Wulanwulahu-Yushu Fault is an important active fault at the boundary area between Bayankala block and Qiangtang block.The slip rate of this fault in the late Quaternary is of fundamental importance for analyzing the seismic hazards and kinematic characteristics of neighboring active blocks.Due to the limited field conditions,the study of the late Quaternary fault activity on the eastern segment of this fault is rare.On the basis of interpretations of remote sensing images and field investigation,the eastern segment of this fault is active since late Quaternary and the offset geomorphic features are prominent,displaying left-lateral and high-angle thrust faulting.Using the methods of detailed geomorphic mapping,geological survey,differential GPS survey,optically stimulated luminescence(OSL)dating and radiocarbon(¹⁴C)dating,this paper makes an analysis of the late Quaternary geomorphic features and slip rate of the eastern segment of this fault.Four typical sites on the fault,including Xiabatang,Zhada,Shangbatang and southwest corner of Batang Basin,were selected for the field investigation.At Xiabatang,the vertical slip rate of the fault is 0.23～0.28mm/a since around 22～27ka BP,0.40～0.51mm/a since 4～5ka BP,and left lateral slip rate is 6.0mm/a since 27ka BP.At Zhada,the vertical slip rate is 0.23mm/a since around 24ka BP.At Shangbatang,the vertical slip rate is 0.45～0.63mm/a since around 6～9ka BP.At southwest corner of Batang Basin,the left lateral slip rate is 4.0mm/a since 150ka BP.The average vertical slip rate of the eastern segment of Wulanwulahu-Yushu Fault is 0.23～0.28mm/a since late Pleistocene,the average vertical slip rate is 0.40～0.63mm/a since early-mid Holocene,and the left lateral slip rate is about 4～6mm/a since late Quaternary.

Lots of different ideas stay on whether the Dongbeiwang-Xiaotangshan Fault in the northwest of Beijing exists or how it displays and acts.This paper analyzes the present seismic prospecting data and drill logs from exploration of active faults in Beijing urban areas,and reaches conclusion that the Dongbeiwang-Xiaotangshan Fault does exist as a subsurface fault and it is 40km long,trending NNE.Divided by the Nankou-Sunhe Fault,we name its northeast segment as the Xiaotangshan Fault and the southwest segment as the Dongbeiwang Fault.The Xiaotangshan Fault is active in early Pleistocene but not in middle Pleistocene.The Dongbeiwang Fault is active in the end of mid-Pleistocene but not in late Pleistocene.

The May 12,2008 M_S 8.0 Wenchuan earthquake in Sichuan Province,China produced a 240km long co-seismic surface rupture zone along the Longmenshan Central Fault.Our investigation focuses mainly on the three regions along the co-seismic surface ruptures,i.e.the Nanba Town and the Fenghuang village on the northern segment of the rupture zone,and the Yingxiu town on the southern segment.We studied the river terraces in these regions offset by the active fault,measured the surface ruptures and the fault scarps on the multilevel terraces and obtained the height of the fault scarps on each terrace,namely,the cumulative vertical slip of the active fault recorded by terrace,through data calculation and analysis.If we use the vertical slip of this earthquake as the average vertical slip of the paleoearthquakes,then the ratio of the cumulative vertical slip of each terrace to this average vertical slip is the cumulative times of paleoearthquakes recorded by each terrace.The research results show that T₁ of every study area has undergone only one paleoearthquake event ever since its formation,T₂ about 5 paleoearthquake events,T₃ about 9～11 paleoearthquakes and T₄ about 20 paleoearthquakes.Based on the research result of this paper,and combined with the previously dating ages of the terraces,we can obtain some reliable data about the recurrence intervals of the paleoearthquakes.

Field investigation on the surface ruptures of the M_S8.0 Wenchuan earthquake along the segment between Beichuan and Qingchuan shows that there is one surface rupture zone developed on this segment,which extends generally along the Beichuan-Qingchuan Fault zone.Observation at Huangjiaba Chenjiaba,Guixi,Pingtong,Nanba,and Shikan suggests that the surface ruptures on this segment spread continuously along the trend of the fault,with single structure and a length of 60～90km.The surface rupture has not reached Guanzhuang of Qingchuan county.The observable rupture zone is about 62km,between Beichuan and Shikan,trending 20°～55° in general,dipping NW with an angle of 70°,showing mainly thrusting with dextral strike-slipping.The most distinct feature of the surface ruptures of this earthquake is the vertical surface bending,which indicates the thrusting of the deep fault.Its horizontal motion on this segment displays as dextral strike slipping,without sinistral slipping component.The value of the vertical coseismic displacements decreases gradually from 3m at Huangjiaba to about 1.5m at Nanba and Shikan;The amount of the dextral displacements does not change evidently,generally between 1.5m and 2.0m.Features of the surface rupture show that the causative tectonics of this M_S8.0 Wenchuan earthquake is the Yingxiu-Beichuan-Qingchuan Fault,whose movement is characterized mainly by thrusting,with a dextral slipping component,and the thrusting direction is from west to east.

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.

Identification of potential seismic zone follows the earthquake structure analogy and seismic activity repetition principles at present.Active fault segmentation is an important aspect and should be considered when identifying potential seismic zones.There are three different segmentation plans along Daqingshan piedmont fault,Inner Mongolia.This article compares and analyses the segmentations and then gets a new potential seismic zone identification plan along Daqingshan piedmont fault.Identification of potential seismic zone includes the range subdivision and the estimation on the maximum earthquake magnitude of potential seismic zones.This article sub-divides the ranges of potential seismic zones according to active fault segmentation plan along the Daqinshan piedmont fault proposed by Ran Yong-kang.Ordos Massif is surrounded by depression zones which have similar earthquake structures and historical earthquake records with magnitude over 8 expect the Hu-Bao depression zone.So,this paper compares Daqingshan piedmont fault with other depression zones around Ordos Massif,especially the Huashan piedmont fault,and gets the conclusion of the maximum earthquake magnitude of Daqingshan potential seismic zones.

We estimate the slip rates of three faults in the central segment of Longmenshan Fault zone, namely, the Maowen-Wenchuan Fault, the Beichuan-Yingxiu Fault and the Jiangyou-Guanxian Fault, based on the measurement and dating of deformation of Late Quaternary terraces along the Minjiang River and its tributaries. The three-level Late Quaternary terraces, T₁, T₂ and T₃, are well developed along the Dujiangyan-Wenchuan reach of the Minjiang River. The cross profiles show that T₃ and T₁ have undergone a complete development process. The thermoluminescence ages of the upper deposits on T₁, T₂ and T₃ are 9～13ka BP, 19～30(ka BP) and 51～58ka BP, respectively. Therefore, we can constrain the ages of T₁, T₂ and T₃ surfaces to 10ka BP, 20ka BP and 50ka BP, respectively. The synchronous three-level terraces also exist in the valleys of the Baishahe River and other tributaries of the Minjiang River. These river terraces are laterally and vertically dislocated by the Longmenshan Fault zone. According to the dating and vertical displacements of river terraces, the Late Quaternary reverse slip rates of the Maowen-Wenchuan Fault, the Beichuan-Yingxiu Fault and the Jiangyou-Guanxian Fault are estimated to be 0.5mm/a, 0.6～0.3mm/a, 0.2mm/a, respectively. According to the lateral displacements of river terraces, the Late Quaternary dextral strike-slip rate of the Maowen-Wenchuan Fault and the Beichuan-Yingxiu Fault averages 1mm/a each. The late Quaternary faulting of the Longmenshan Fault zone is characterized with intermittency. Three faulting stages can be identified. The first one is between 50ka BP to 20ka BP, the second one between 20ka BP to 10ka BP, and the latest starts at 10ka BP. The existence of thick alluvial deposits in the present channel indicates that the uplift of Longmenshan Mountains is more complex than previously estimated.

Late Quaternary tectonic movement in the northeast part of Shandong Peninsula was dominated mainly by integral uplift,while fault activity inside the peninsula was relatively weak. Late Pleistocene faults are limited to some local areas,and one of them is the newly discovered Dongdianhou Fault. The fault is located to the north of Taiboding Mountains,associated with a broad fracture zone of 100m wide. Outcrops of fault profile can be observed in many places along the fault strand. The fault has a general strike of nearly East-West and a total length of about 20km. Geomorphically,the fault appears as a straight fault valley consisting of 3 upper reaches of stream. The mountains on the southern side of the fault are obviously higher than those on the northern side. The cross section of the fault to the west of Xinshangzhuang Village shows that the fault displaces the unconsolidated rubble bed dated to be 84～75ka BP in age,resulting in a 1 8m high colluvial wedge,which is overlain by talus bed dated to be 64ka BP in age. The vertical slip rate of the fault is estimated roughly to be about 0.16mm/a. Soft fault gouges were observed on the fault planes exposed to the south of Diaoyushi Village and to the east of Taoyuan Village,and the age of the gouges is dated by thermoluminescent method to be 82ka BP. The characteristics of the fault and the age of overlying layers indicate that the latest faulting event occurred in early and middle stage of Late Pleistocene,while since the late stage of Late Pleistocene the fault has not ruptured the surface. According to the relation between surface rupture parameters and earthquake magnitude,it is estimated that the magnitude of the maximum potential earthquake on this fault is 6/2.