From March 8^th to 29^th, 1966, five earthquakes(M≥6)occurred in the Xingtai area, with the M_S6.8 earthquake on March 8^th and the M_S7.2 earthquake on March 22^nd being the most severely damaged. The Xingtai earthquake resulted in over 8 000 deaths and the economic losses up to 1 billion yuan. The Xingtai earthquake has opened the scientific practice of earthquake prediction in China and is a milestone in the development of earthquake science in China.

Based on previous research results, there is a deep fault beneath the Xingtai earthquake area, which is the energy source of earthquakes, while there is a relatively independent fault system in the shallow part, which is generally recognized by scholars. However, the divergence regarding the seismogenic structure of the Xingtai earthquake mainly focuses on the unclear coupling relationship between the deep and shallow structural systems in the seismic area. The structural relationship between deep seismic faults and the shallow Xinhe Fault system requires new evidence to determine. In addition, previous scholars have proposed the viewpoint of “Newly generated Fault”, which can better explain the rupture characteristics of the Xingtai earthquake, but it still needs to be supported by the inversion results of the seismic rupture process based on the three-dimensional crustal fine structure. There are many small earthquakes in the Xingtai area. Deep structural information can be obtained using small earthquake data. Especially after 2009, the significant improvement in earthquake positioning accuracy in North China has made it possible to obtain new insights into deep structures. By locating small earthquakes, the spatial distribution and motion characteristics of faults are characterized, and seismic travel time tomography reveals the deep crustal velocity structure characteristics of the earthquake area. Combining previous geophysical exploration results, conducting deep and shallow structural analysis is of great significance for studying the spatial distribution, motion characteristics, and coupling relationship between deep and shallow structural systems of the fault system in the study area. The continuous aftershocks after the 1966 M_S7.2 earthquake in Xingtai, Hebei Province, have provided favorable conditions for conducting studies on deep tectonic structures in the region.

In this paper, based on the observation data of the Hebei seismostation from 1991 to 2021, we obtained the precise position results of 9 644 earthquakes in Xingtai and its neighboring area using the double-difference positioning method, and depicted the spatial patterns of deep ruptures. Based on the observation data of the North China Mobile Seismic Array from 2006 to 2008, 38 578 P-wave arrivals were used to obtain high-resolution travel time tomography results in the study area. This study shows that there are strong lateral heterogeneities in the velocity structure of the crust in the study area, with obvious low-velocity anomalies in the upper crust and high-velocity anomalies in the middle and lower crusts between the Xinhe Fault and the Yuanshi Fault, and the Xingtai earthquake is located at the junction of the high- and low-velocity anomalies, which has the medium conditions for accumulating large amounts of strain energy and is prone to rupture and stress release. The general trend of the dense zone of small earthquakes in the Xingtai earthquake area is relatively consistent with that of the eastern boundary of the high- and low-velocity anomalies. It is assumed that the deep and shallow fractures spreading along the eastern boundary of the high- and low-velocity bodies have been connected up and down and that the boundary of the anomalies is also a part where velocity changes are relatively strong and easily lead to seismic rupture; the results of various seismic and geological surveys have revealed that a deep major rupture that cuts through the entire crust exists beneath the Xingtai earthquake zone, with SE tendency and the upper breakpoint located near Dongwang, and the Xingtai earthquake prompted the deep and shallow pre-existing ruptures to connect from top to bottom.

Through simultaneous inversion of earthquake hypocenters and velocity structure, we obtained the precise locations of earthquakes occurring from 1981 to 2013 in northern Shanxi and the 3D velocity structure, and analyzed emphatically the Kouquan Fault. The result of earthquake relocation shows that earthquakes are concentrated in the central-north segment of Kouquan Fault and the distribution is sparse towards both south and north end of the fault, which indicates that the strong activity is in the central-north segment of Kouquan Fault and the seismicity becomes weaker towards both ends. The result of velocity structure shows that the earthquake concentrated segment of Kouquan Fault is on the side of relative low-velocity area in the high-velocity body, and the south segment of Kouquan Fault is the continuous low velocity. We can recognize the velocity gradient zone from the obvious depression near the Kouquan Fault, which, as we preliminarily speculate, may be the evidence of the presence of Kouquan Fault(or basement detachment)at the deep part. The parallel velocity profile (velocity ratio profile) to Kouquan Fault shows that the earthquake cluster in the central-north segment of Kouquan Fault is located in the abrupt change zone from high to low velocity(from high to low velocity ratio).

With the advances in simulation techniques and understanding of geodynamic processes,numerical simulation is likely to play an increasingly important role in the research of seismic hazard analysis and earthquake prediction.In this paper,on the basis of the paper "A preliminary study on the application of numerical simulation methods to earthquake prediction research(Ⅰ)",the possible application of uncoordinated deformation analysis,Coulomb stress changes and earthquake probability modeling to the study of earthquake prediction is further discussed.When rock deforms from the elastic into the yield stage,the system is in a critical unstable state,the rock movement may deviate from the normal track and become complicated.The study results show that,before Wenan earthquake(M_S 5.1)on July 4,2006,GPS velocity was well consistent with the numerical simulation speed in most areas of North China,while there were some differences in some regions,especially in the northeast of the North China Plain block,where big inconsistency in movement characteristics occurred,resulting perhaps from the preparation of Wenan earthquake.Research on earthquakes triggered by Coulomb stress change is a focus problem now.Numerical simulation may play an important role in the analysis of Coulomb stress changes.By constructing three-dimensional dynamic model,the effect of various factors on the value and distribution of Coulomb stress change can be simulated,and more realistic results can be obtained.By numerical simulation of Coulomb stress changes to seismic activities beneath Sichuan Zipingpu reservoirs,it is found that with the increase of reservoir water storage time,the pore pressure diffusion in the effective additional stress field will be gradually expanded to the range of more than 10km underground.The regional effective additional stress field and seismic activities show different characteristics in several typical regions.The United States Southern California Earthquake Center has tried to study the earthquake probability as research objectives.It is worthy of referencing in China's earthquake research.Computer simulation of synthetic earthquake catalog is an effective way to solve the lack of data.The future direction of development should be a more realistic three-dimensional dynamic model,taking into account the multi-field coupling between heat,fluid and etc. ,improving hardware and software conditions and shortening the calculation time step,obtaining more complete information on fault movement,and simulating the fault activities.

Earthquake preparation and occurrence is a complex physical process.Although the earthquake abnormalities are varied,the strain energy accumulation is requisite before an earthquake.Earthquake prediction analysis must consider the strain energy accumulation process.As hard to go into the Earth's interior,direct measurement of stress and strain in deep focus is very difficulty.The use of numerical analysis,which constructs three-dimensional dynamic models of the crust and upper mantle to simulate the rock deformation process,is currently one of the most effective methods to study the crustal energy transfer and accumulation.The simulation result of current crustal deformation is consistent with the existing GPS data around the Eastern Himalayan Syntaxis and its surrounding areas,in that the crustal horizontal displacement field of the eastern Tibetan Plateau rotates clockwise around the Eastern Himalayan Syntaxis.Current effective stress concentration areas mainly distribute along the block boundary fault belts around the Eastern Himalayan Syntaxis,especially along the southeast section of Jiali Fault,Moto Fault,Apalong Fault,India-Myanmar subduction zone and the Sichuan-Yunnan border region.It should be noted the risk of future strong earthquakes in these areas.In the adjacent interconnected tectonic areas,the blocks and faults are interrelated and interacted each other.When an earthquake occurs in a region,the rapid displacement and deformation of rock will inevitably lead to displacement and deformation of the associated blocks and faults; strain energy will transfer from one region to others.The numerical simulation results of deformation process in the Capital area from 1989 to 1998 clearly show that the high strain energy concentration region shifted from Datong area where 1989 earthquake(M_S 5.8)occurred to Zhangbei area where 1998 earthquake happened.It illustrates that the application of numerical simulation analysis method may help us predict the possible strain energy transfer process,thus,providing the reference target regions for earthquake monitoring.

In-situ stress measurement was carried out near the eastern segment of Wanyaogou Fault,western segment of Yamalike Fault,and middle-eastern segment of Xishan Fault in the urban area of Urumqi.The characteristics of tectonic stress magnitude,direction and distribution were obtained.The borehole HFZK3 is located on the south side of the eastern segment of Wanyaogou Fault,the depth is 62.13m;The borehole HFZK5 is located on the south side of the western segment of Yamalike Fault,and the depth is 30m;The boreholes HFZK9 and HFZK12 are located on the middle and eastern segment of Xishan Fault,and the depth are 34m and 54.5m,separately.According to stress measurement data,the direction of maximum horizontal principal stress is NE-NEE,different with the direction of regional tectonic stress of SN-NNE.This indicates that,effected by fault activity,the stress state near fault is obvious different with the regional tectonic stress field.The activity of fault zone is discussed using stress measurement data.The horizontal stress increases with depth,and its relation with vertical stress is σ_H>σ_h>σ_v.Such stress state is propitious to reverse faulting.The result is consistent with geological study.According to Coulomb friction criteria and taking m=0.6～1.0,the stress state near fault reaches or exceeds the critical value of generating frictional sliding along reverse fault,indicating that the current tectonic activity is reverse faulting.

The Lijiang-Xiaojinhe Fault lies in Northwest Yunnan Plateau, striking N40°E and extending for 360km. It is an important transverse active fault, obliquely cutting the "Sichuan Yunnan Rhombic Block" in southwest China. Interpretation of aerophotos, field investigation, and age determination of this active fault have revealed that the fault is an active reverse sinistral strike slip fault, dipping northwest at high angle. Relocation of basins and analysis of synsedimentary dislocation of the basins provide an estimate of the horizontal dislocation amount along the fault of 7.4～7.6km since Quaternary. In addition to the large scale horizontal movement, the vertical differentiation of relief and landforms on both sides of the fault is also strikingly shown. The relief along the fault strand from Lijiang northeastward to Ninglang and Muli is higher on the northwest side and lower on the southeast side, between which lie a series of steep fault scarps and a topographically steep zone. Comparison of the relief on both sides of the fault shows that the vertical throw of the fault is 500～700m or more. The horizontal and vertical dislocation rates along the Lijiang Xiaojinhe Fault since Quaternary and since middle Pleistocene are estimated preliminary to be 3.7～3.8mm/a and 1.0～1.5mm/a, respectively. In the northeast of Lijiang, especially along the Changping Muzhuda and Baerqiao area in Ninglang, a series of evidence of sinistral horizontal dislocation, such as offset ridges, gullies, proluvial fans, and terraces was found. The amount of horizontal dislocation varies from several meters to hundreds meters. All these may indicate the characteristics of obvious movement along the fault since late Quaternary. The amounts of horizontal dislocation and the related data of age determination indicate that the average dislocation rate since late Pleistocene is in the range of 2.6～ 4.0 mm/a with a mean value of 3.3mm/a; the average dislocation rate since Holocene is in the range of 2.5～5.0mm/a with a mean value of 3.5mm/a. The similarity of slip rates in various stages of Quaternary indicates the relative stability of movement along the fault and the long range persistence of the active block boundary. The compression and overthrust of the shallow layer crust, the existence of deep geophysical gradient zone and zonal area of strong seismicity along the fault, as well as the variation in movement rate of blocks on both sides of the fault reveal the significant shielding effect of the Lijiang Xiaojinhe fault on the southward migration and "flow" of the mass in the middle upper crust along the "Sichuan Yunnan Rhombic Block" after the uplift of Qinghai Xizang Plateau.

We have conducted an integrated survey and investigation on the Quaternary activity of the Liaocheng-Lankao buried fault. The used methods include geochemical exploration, shallow seismic exploration, drilling geological profile and neo-strata dating. The object is to determine the accurate location of the fault, dislocation amount of each time period since Quaternary and the offset age of the last time of dislocation. The results show that the dislocation of the fault extends upward to the depth 20m or so below the surface. This fault has been active in early Holocene time. The average slip rate of the fault is 0.12mm/a.

Unlike low resolution (>1000 years) δ ¹⁸O record which mostly indicates temperature change in the past,variations of high-resolution (<100 years) δ¹⁸O record of stalgmite mainly reflect changes in rainfall and the isotopic compition of moisture source in the study area. The δ ¹³C value of speleothem is mainly controlled by isotope composition of soil CO₂that consists of isotopic composition of C₃and C₄plants. The C₃/C₄ratio is strongly correlated with climatic change. When the δ ¹⁸O and δ ¹³C shift to more negative values,the ratio of C₃/C₄indicates wet climate increased precipitation,development of forest. All those climatic conditions may indicate summer monsoon strengthening in the study area. This thoutht provides a new approach to reconstruct high resolution paleomonsoon records. We have first demonstrated this new idea throughout a series studies in Shihua Cave,Beijing. A 12.5cm stalagmite was subsampled at 1mm interval (～25 years resolution) and 109 samples were collected for δ ¹⁸O and δ ¹³C analyses. Using Hendy rule,cave temperature and δ ¹⁸O H₂O ,we have illustrated the isotopic equilibrium between precipitated calcite and its parent solution and the reliability of our measurement. The δ ¹⁸O and δ ¹³C records provide climatic information during the past 3000 years in Beijing. Our results show that there are six apparently climatic cycles during the last 3000 years in Beijing. The wet periods were peaked at 2860,2350,1850,1480,790 and 150 yr B.P.,respectively,with a time step about 500 years. After 600 yr B.P. ,all of the δ ¹³C values show much heaiver than 3ka-mean values. We suspect that this change in C₃/C₄ratio (de-forest) was influenced by human activity also. There is a good agreement in the comparisons of the paleoclimate interpreted from the speeothem δ ¹⁸O and δ ¹³C records with historical records of temperature and precipitation in Beijing,and precipitation in North Central China reconstructed from tree-ring study in Huashan Mountain. Climate in Beijing during the last 500 years,was strongly influenced by the Little Ice Age event which had been found as a global climatic event. In Beijing the climate was relativly arid during the early period of the Little Ice Age. The climate became wetter after 400 yr B.P. and reached a maximum moisture for the 3000 yr period at ～150 yr B.P. Since 100 yr B.P.,the climate has become arid again.

The application of radiocarbon dating of speleothems is often limited by "dead carbon" contamination.In this paper we have established a new model to correct contamination of "dead carbon" and determine growth rate of a stalagmite which was collected from Shihua cave, Beijing.Based on the measurements of ¹⁴C activity on 11 samples from the stalagmite, we have found that 5 of the samples have little "dead carbon" contamination and four of the samples contain relatively constant contamination of "dead carbon".The two groups of the samples gives us two linear relationships between natural log of ¹⁴C activity and depth with the same slopes but different intercepts.These data results illustrate that the stalagmite has a relatively constant growth rate and no growth hiatus which are the assumptions of the model.Using the model we have reconstructed the chronology Of the stalagmite and obtained a mean growth rate of 0.042 mm/a.The results are in good agreement with the mean growth rate determined by the annual growth banding and the youngest age measured by ²¹⁰Pb method.

We have measured δD, δ¹⁸O and ³H of surface water, spring water and drip water in Shihua cave area.The average values with the standard deviation of δD and δ¹⁸O are (-65.4±3.5)‰, (SMOW) and (-9.4±0.3)‰(SMOW), respectively.The average tritium content is (30.8± 4.5)TU.These data demonstrate that the drip water in Shihua cave represents fast penetration of surface water above the cave, and the mixing effect of old groundwater is negligible.Therefore, the variations in isotopic composition of cave drip water can reflect changes in isotopic composition of surface water which represent weighted mean annual isotopic composition of precipitation in the locality.The major factors that influence isotopic composition of cave drip water are mean annual air temperature, mean annual rainfall and change in moisture source.This research work forms the basis of using high-resolution δ¹⁸O record in speleothem to reconstruct paleoclimatic record in the region, especially for paleomonsoon variability.

A deep sounding work by converted waves of earthquakes has been conducted in Xingtaiearthquake region. As a result, 6 cross-sections of deep structure in Xingtai earthquake area have been constructed (3 in NW trend and others in NE trend). On the bases of these sections the structures of major deep crustal interfaces G,C and M were determined. At the same time, the velocity models of P and S waves were constructed. Moreover, background of 3-D deep structure and the dynamic conditions for earthquake occurrence are also discussed.

The studying sections are situated in the northwest and southeast of the Fuyun county, Xinjiang. Many pollen grains of shrub and herb plant have been found in the sediments from the sections of Tuerhong, Gangou, Kalaxiangeer and Wulunguhe, mainly belong to Ephedra sp., Artemisia sp., Chenopodiaceae and Compositae.On the basis of the analysis results it is believed that the vegetation related to the sediments of the sections is mainly typical one of a desert-steppe and steppe vegetation.The result of sporo-pollen analysis shows that there was a climatic fluctuation during the formation of the sediments of these sections. The prevailing climate was warm and dry.The results of pollen analysis are comparable with the pollen data on the Holoce-ne sediments in many regions of our country. Moveover, the seven samples from these sections for ¹⁴C dating give the age value of 2000-7000a. For this reason the four studying sections can be ascribed to the Holocene.Based on palynological data from both sides of the fault in Gangon section, the geological age of the fault formation can be infered to be impassable Holocene.

Because of recent activity of the fault zone of northern piedment of Nanhua Mountain,21 gullies along the fault zone within 16 kilometers from Caiyuan to Luanduizi were obviously offsetted,showing well oriented sinistral displacements.This paper studies geological and geomorphological features,precoss and offsets of the gullies,and determines for the fault zone the average slip rate (4.3mm/yr,since Late Pleistocene),on the basis of ¹⁴C dating of deposits and data on the rate of head-ward erosion.Moreover,according to observations in the field,the maximum displacement for the seismic fault in the epicentral area of Haiyuan M 8.5 Earthquake of 1920 is about 6.9m.On the basis of above data,the recurrence time of 8.5 strong earthquake along the fault zone has been estimated as about 1600 years.

The strata of the Holocene,which was divided on the basis of radiocarbon datings and sporo-pollen analysis,indicate that the Holocene strata in Dali area can be found mainly along the Erhai lake and surroundings of Xi lake and Cibi lake,as well as the piedmont belt.The Holocene sediments are of diluvial and river-lacustraine origin.The Holocene boundary is marked by a layer of lacustraine sediments consisting:of peat or its similar and is about 15 meters at a depth beneath the Eryuan region.And the sandy gravel and gravel distributed on the eastern slop of Mt.Diancangshan can be ascribed to the Early-Middle Holocene.

The optimum numerical filter is a useful mathematical tool for separating waves with a given period or eliminating short period fluctuations in a time series, including three types: low-pass filter, band-pass filter and high-pass filter.In this paper, a new formula for calculation of sinusoidal integral is presented and the optimum numerical filter is already applied in different fields of geology.