The Longling-Lancang fault zone is a newly emerging fault zone, which is composed of multisecondary faults, distributed in the obligate or clustered types, and characterized by the zoning of active faults, earthquake faults and earthquakes. Its kinematic feature is dextral extensive and the formation epoch is early-middle Pleistocene. It is still active in the later period. The rupture in the future tends to cut across the tectonically-blocked segment, discontinuous segment of the fault and then through the whole fault zone. The formation of the nealy emerging fault zone has close relation with the uplift of the Qingzang Plateau. The composite action by the material fluid from the north to the south and the intrusion of Asamu block towards northeast makes the Dianmian block to rotate in a counter-clock wise direction and forms a new dextral shear, NNW-trending fault zone in the central area of the block.

Based on new data and studies on active blocks in recent years, we propose the principle, evidence and method for division of active blocks of the south region of Sichuan Yunnan Province. It is suggested that the Quaternary active faults which have major scales and have been active till present are the necessary and primary boundary conditions for block division. The newly formed Tengchong-Jinghong NNW zone and Dali-Chuxiong NWW zone have an important role in the block division. In the light of the nature of faults, motion modes, and GPS data the present-day active mode of each block is analyzed. It is concluded that earthquakes of M 7 or greater occur on the first class boundaries of active blocks, events of M6～M7 on the second class boundaries, and the active blocks of secondary class are the main locations of major earthquakes.

The Xiadian fault is one of the most important concealed active faults in the northern part of the North China Plain. The Sanhe-Pinggu earthquake (M=8) is the latest surface rupturing event on this fault. Two stratigraphic drill logs on both sides of the Xiadian fault are chronologized by using thermoluminescene and ¹⁴C dating methods. Comparison shows a differential sedimentation on both sides of the fault in the last 26 ka B.P. The stratigraphic marks are established for identifying paleoearthquakes in the drill logs and 11 events are recognized. The main results of this study include: (1)The vertical slip of the Xiadian fault decreased since the Last Glacial Maximum in the past 26ka B.P. The vertical slip rate reached 1.2mm/a during the period of 21～26 ka B.P., 0.98mm/a during the period of 10～21 ka and 0.34mm/a in the past 10 ka B.P., respectively. (2)11 paleoearthquakes are identified by the drill logs which indicate an irregular recurrence behaviour in the past 26ka B.P. The paleoearthquakes clustered with a relatively short interval of 900～1 200 years in the Last Inter-Stadial and Last Glacial Maximum (19.3～26 ka B.P.), while several paleoearthquakes recurred quasi-periodically with an interval of 3 770～5 800 years in the Post Glacial. (3)The paleoearthquake recurrence pattern seems to be associated with paleo-climate variation in the Last Glacial. The earthquake clustering occurred in the Last Inter-Stadial and Last Glacial Maximum with a short recurrence interval. The recurrence interval became longer in the Post Glacial.

The reverse fault fold zones in the foreland basin of northern Tianshan is a typical active compression area in interior of continents. The research of the surface and deep structure,and its relationship in the active compression tectonic region is extremely important for the understanding its seismogenic structure and dividing its potential earthquake sources. On the basis of detailed research on the major active tectonics and synthetical studies in northern Tianshan,the deformation of the structure,earthquakes and active tectonics,and the relationship between surface and deep structures have been discussed in this paper. Finally,a few questions have been put forward in the process of potential earthquake source dividing in the active compression tectonic belt. Based on the research of the 1906 Manas earthquake (M7.7) and paleoearthquakes on the active reverse faults,we can know that the blind active crust ramp under the piedmont in the northern Tianshan area is the place of large earthquake occurring,and divided the blind ramp into two segments at the Jinguohe area. The active blind crust ramp may have two large potential earthquake (M8.0) sources. There are eight active anticlines in the northern Tianshan,west Urumqi. We can also compare these active anticlines with the active folds in the west region of the United States of America,and conclude that these active anticlines can only produce some middle earthquakes (M6.0). All the active anticlines in the northern Tianshan,west Urumqi,may have eight potential earthquake sources.

The regional seismotectonic environment of the Zhangbei Shangyi earthquake is stated in detail together with its seismic intensity distribution,co seismic ground fissures,focal mechanism solutions and interpretation of linear structures on the MSS satellite images around the epicenter.Its possible seismogenic fault or structure is also discussed.It is suggested that this earthquake was resulted from the most recent abrupt slip on a NNE trending fault at the northwestern termination of the Zhangjiakou Penglai fault zone.The future seismicity of the Zhangjiakou Penglai fault zone is worth to pay attention.

The recognizable segment boundaries of the Rukuu reverse fault system are obtained through study of coseismic surface ruptures for the 1896 Rikuu earthquake, long-term faulting behaviour and offset geomorphology. They are the transition areas for permanent change of fault scarps, watershed altitudes most nearby the faults and geometrical structures of active reverse faults in cross section, and buried tranverse bedrock ridges. The stepovers and fault trace gaps in kilometers' order can not stop or slow down effectively coseismic-surface-rupture propagation along the reverse fault strike, thus, can not serve as segment boundaries for reverse faults. The seismic risk on the Senya and Yokote segments of the Rikuu reverse fault system along the eastern margin of the Yokote basin is also assessed briefly.

Three basic geomorphic units, which were developed in response to the climate changes during the last glaciation, are recongnized along the northern piedmont of the ENE-trending Liulengshan range from airphoto interpretations and field observations.These three units are the inter-stadial fluvial fan (S₃) about 23～53 ka old, the maximum-glacial fluvial fan(S₂) about 10～23 ka old and the post-glacial fluvial fan(S₁) about 1～10 ka old, respectively.Five fluvial terraces(T₀～T₄) were also developed owing to the climatic temperature fluctuations on thousandyear scale.These geomorphic units(S₁～S₃) and fluvial terraces(T₀～T₄) are chronometrically dated by thermoluminescence.Stripped geomorphic mapping shows a natural segmentation in offset-geomorphology along the norhern piedmont fault of Liulengshan range.Six segments can be divided in the mapping areas and they are the Xifutou, Donghouzikou-Dawangcun, Xitunpu-Qiulin, Huoshilin-Qiuchangcheng, Huajialing-Xiejiayao and Longmazhuang-Xinpu segments from the west to the east, respectively.A set of quantitative data (faulting ages, vertical displacements and slip rates) are obtained from long-distance topographic profiles across the offset geomorphic units or fuvial terraces.The average Holocene vertical slip rates are 0.43～0.48mm/a for the Donghouzikou-Dawangcun segment, a bout 0.45 mm /a for t he Xitunpn-Qiulin segment, and 0.53～0.55mm/a for the Longmazhuang-Xinpu segment.The faulting irregularity is demonstrated by temproal and spatial flucturation in vertical slip rates during the Late Quaternary.The period of 15.6～7.6ha B P is the main phase of intensely verical faulting along the northern piedmont of Liulengshan range.

Quantitative relationship between length(L)and maximun displacement(D)of strike-slip surface rupture zone, earthquake magnitude(M_s) and recurrence interval(T) for earthquakes in west China is empirically fitted. The result indicates that the earthquake magnitude M_s and recurrence interval T are closely associated with both rupture length L and maximum displacment D.M_s can be estimated from multiplication product LD, and T is closely related to the ratio D/L. Given M_s or LD for an earthuqake,the larger the D/L valus is,the longer the recurrence interval T becomes. Given surface rupture length L for an earthquake with longer recurrence interval T, its M_s or LD is larger. Given maximum displacement D for an earthquake with larger M_s or LD, its recurrence interval is shorter.

The three-dimensional structure of the ground fissure zone in the area of Datong Railway Bureau is studied in detail form the data of field investigation, geological trenching and shallow seismic prospecting, as well as analyis of its neotectonic background and underground water overextraction. The developing ground fissure zone has been propagating westwards at a rate of 260 ～ 520 m/a since 1983; Its differential movement rate across the zone reaches 22.1～24.4mm/a. The extensional rate of the main fissure is 1.11～11.6mm/a, vertical slip rate about 0.2～8.57mm/a, and left-lateral slip rate about 1.87～3.57mm/a. Its active behavior belongs to a brittle-plastic model. This ground fissure zone has been caused by the recent creep along the Baimacheng fault-aburied active fault. The local overextraction of the underground water has accelerated the development of the ground fissure zone. The formation of the ground fissures is an aseismic geologic hazard.

The northern piedmont fault of the Liuleng Mountain in the extentional region of the north-ern end of Shanxi graben system lies along the southern edge of Yangyuan basin and controls theorigin and development of the basin, It is a dip-slip normal fault, NEE-trending and N-dipping.Two moderate and large earthquake swarms (Ms=6.1, Ms=5.8) successively occurried alongthe fault in 1989 and 1991.The fault consists of a marginal faul of the basin (F₁)and a newly formed fault(F₂) cuttingthe late Pleistocene to Holocene alluvial deposits within the basin. The F₁ and F₂ faults form astepped fault zone along the northern piedmont and joint together into the western segment. Thefault activity is characterized by inheritant displacements. It cuts stream terraces of different agesand piedmont loess terraces, causing two basalt eruptions (K-Ar age of the basalt and TL age ofits underlying baked bed is 1.71±0.41Ma, 18.29±1.39～19.7±1.54×10⁴a B.P. respectively). Later activity along the fault offset the basalt to form a 30～50m high scarp. At the middlesegment of the fault, F₁ has been inactive since late Pleistocene,whereas newly formed fault F₂ at 2～3km north of the edge of the basin has offset alluvial fan surface and stream terraces of different ages since late Quaternary. The eastern segment of the fault cuts the third terrace at thejunction of Sanggan and Huliu rivers and formed a 50～60m high scarp.Several topographic profiles across the scarps on different segments and un-coeval geomorphic surface were mapped to obtain vertical offset by using auto-level. Ages of the different geomorphic surfaces were determined by TL and ¹⁴C. Average vertical slip rate is 0.43～0.75mm/aduring the late Pleistocene to the Holocene. The age of the youngest layer cut by the fault is 0.76～0.86×10⁴a B.P..

The 1906 Manas earthquake is an important event in the northern Tianshan of China. TheSeismogenic fault controlling this earthquake has not been well understood. Detailed field investi-gation indicates that the ground ruptures in the epicentral area were caused by gravitational andshaking effects during the earthquake. The fresh fault scarps along the Tugulu-Manas-Houer-goush reverse fault and fold zone are the possible surface ruptures associated with the 1906 Manasearthquake. The displacement is between 0.2 and 0.5m. Total length of the fault scarp is lessthan 10 km which is far more less than a normal rupture length associated with an earthquake of magnitude 7.7.Anticlinal uplifting along this reverse fault and fold zone indicates that the earthquake probably occurred along low-angle reverse fault at depth as a blind reverse faulting event.The surface rupture and deformation took place far away from the epicentral area. Most of thecoseismic deformation was accomodated by folding and uplifting,and only less than 10 km surface rupture was formed.Thus,the 1906 Manas earthquake is probably a“folding earthquake”.

Shanxi graben system is one of the most famous strong earthquake belts on China Continent. In this paper, the problems on recurrence and migration of the historic strong earthquakes (M≥6), the precusory anomalies of the intermediate and strong earthquakes (41/3≤M<7) before M≥7 earthquakes occurring, and linear segmentation of the strain accumulation curves are discussed. The temporary trends of the recent and future seismicities are analysed. Finally the possible seismic risk areas in which intermediate and strong earthquake may occur are also outlined in the graben system.