Abstract:Effects of stress perturbation on acoustic emission（AE） during fault friction are studied by using medium-scale experiments of rock friction,and the characteristics of seismicity caused by coseismic stress change and its implication in earthquake forecasting are discussed based on the experimental results.The experiments indicate that stress perturbation of square wave can obviously affect AE activity,it can trigger some AE events so that AE activity before stick-slip becomes stronger and occurs earlier.The effect increases with increasing average normal stress and perturbation amplitude,and perturbation effect from shear stress（increase） is more evident than that from normal stress（decrease）.In statistics,when stress perturbation is not applied,AE events usually occur just before stick-slip even if there are AE events,i.e.occurring when stress accumulation reaches above ~90%.When stress perturbation is applied,AE events occur earlier before stick-slip,i.e.occurring when stress accumulation reaches ~70% and even much earlier.The experimental results mean that whether the coseismic stress change caused by a strong earthquake can obviously affect strong seismic activity in its neighbour area,it is mainly depentent on if the absolute stress of faults comes close to instablity strength.Small earthquaks can reflect stress state of fault at certain extend,therefore,it is more reasonable to analyze earthquake potential by combing coseismic stress change and activity of small events.However,the uncertainty existing in the process should also be considered.

Abstract:In this paper we attempt to develop a simple algorithm to apply GPS observations to the short-intermediate-term earthquake prediction practices.By using the Load Unload Response Ratio（LURR） values at different stages,the earthquake potentiality in a seismogenic region is evaluated.The LURR time series fluctuats around 1.0 when the source media is in a steady state,and becomes quite high just before a large earthquake.To show the validity of the approach,the 2004 Parkfield earthquake in southern California is chosen as the example.We find that about half a year before the earthquake the LURR time series derived from the nearby GPS stations increased obviously;while from some far GPS stations,we can not observe similar anomaly.Therefore,the anomaly may be resulted from the regional crust stability change.The fact suggests that we can get new precursory anomaly to predict large earthquake by properly disposing GPS measurement data.

Abstract:Taking the annual seismicity trend reports from 1992 to 2007 given by Second Monitoring and Application Center,CEA,as statistical sample,the seismic monitoring and annual earthquake prediction for northeast margin of Qinghai-Tibet block using crustal deformation data are tested.The capacity of earthquake prediction using crustal deformation anomalies is evaluated.The results show that there was no pretermission of prediction for moderate-strong earthquake in 16 years,4 events were predicted correctly and 19 times failed,the accuracy ratio of prediction is about 21%.It is indicated that crustal deformation monitoring has good predictive capacity to moderate-strong earthquake.But caused by the uncertainty of corresponding relationship between crustal deformation and earthquake event,the percentage of failure is much higher than one of accuracy.

Abstract:On the basis of the phenomena of slope shattered deformation and failure after 5·12 Wenchuan great earthquake,the effects of body wave and surface wave in the earthquake are analyzed,and the mechanical mechanism of slope shattered deformation are studied.It is considered that the effect of seismic waves caused the alternate action of the tension stress with values and direction constantly changing acted on the rock and soil mass of slope surface layer,especially on the slope shoulder,the characteristic on perpendicular plane showed overall dynamic change and resulted in the rock and soil mass on shoulder appeared revolution-dump,positive and inverse tension action.Meanwhile,the following shear action,cracking and crushing occurred.The shear action was more concentrated on slide surface.In addition,the bulge tension and torsion forces acted together on the slope surface also.In this paper,seismic wave effect is divided into four kinds of forms： the tension-shearing rupture effect,the interface dynamic stress effect,the potential wedge splitting effect,and the super interstitial hydraulic or pore water pressure excitation mechanism.The analysis results are well in accordance with field phenomena and the result of vibration simulation model,provided an important guide for the post-disaster reconstruction and disaster prevention and mitigation.

Abstract:Through the study and analysis on the seismic tomographic data in the northeastern margin area of Tibetan Plateau,the methodology of crustal 3D database as based on MultiPatch format in ArcGIS and the crustal solid structure model of the northeastern margin of Tibetan Plateau with the modern 3D modeling software and technology are presented.It emphasizes the 3D Geosciences modeling theory,the storage methodology of seismic tomographic data and the main technology of 3D solid model.Then,the main methodology is summarized from the fundamental seismic tomographic data to 3D crustal structure model of the northeastern margin of Tibetan Plateau.

Abstract:Among the secondary mountain disasters triggered by the ＂5·12＂ Wenchuan great earthquake,most were collapses of rock and soil slope.Based on the field investigation along State Road G213 from Dujiangyan to Yingxiu and its Shuimo branch road,the collapse disaster mode,failure mechanism and self-organized criticality（SOC） dynamical characteristics of rock and soil slope are analyzed and summarized in detail.The investigation area covers Ⅸ,Ⅹ,Ⅺ seismic intensity zones,and collapse site numbers are 105.By statistical analyzing the volume and depth of the collapses,it is found that in Ⅸ zone volumes and depths of collapses obey negative power law distribution,display self-organized criticality（SOC） dynamical characteristics,but in Ⅹ,Ⅺ zones the collapse dynamical characteristics does not show self-organized criticality,it is controlled by earthquake intensity.

Abstract:Considering the fundamental solution of Gibson halfspace obtained by Thin-layer method as the Green function for BEM,some parameters in the design of 3-D Wave Impeding Block（WIB） isolation for the Gibson homogenous elastic halfspace and stratified foundation are studied in detail.The result indicates that relatively good isolation effect can be obtained by WIB in the Gibson foundation,while the WIB haves reasonable breadth and relatively small embedment depth.Increasing the thickness and modulus of WIB is most effective way to get a good effect of isolation.The Gibson ground＇s property has some influence on the effect of isolation also.The research in this paper will be helpful for the application of WIB in popular.

Abstract:Based on the middle-small earthquake data from 2001 to 2008 in Anninghe-Zemuhe earthquake belt,100 focal mechanisms of ML≥3.0 earthquakes are calculated.Using mechanical axis tensor method the direction of mean stress field of Anninghe-Zemuhe earthquake belt is given,with direction of NW-SE,which is in accord with the results given by historical moderate-strong earthquakes in the area.The strike-slip earthquakes account for large proportion in all earthquakes and located in narrow areas.The plane and section of apparent stress are plotted after calculating parameters of source spectrum of small earthquakes,it shows that the high value areas are two underground disconnected regions at depths of 5 km and 15 km near Shimian county,at depth of 5 km on Zemuhe fault at south of Xichang city,and at depths of 10 km to 20 km at north of Xichang city,respectively.If relative high value area of apparent stress is thought as indicant of future strong earthquake risk,north segment of Anninghe fault and mid-north segment of Zemuhe fault are the potential strong earthquake risk area.In these areas density and intensity of small earthquakes have increased in recent 8 years.

Abstract:Considering the randomness of earthquake and the nonlinearity of soil,introducing viscous-spring boundary,a loading pattern of inputting acceleration directly in harmonic response analysis is proposed.The practical calculation method of stochastic vibration response for pile-soi-structure interaction system based on pseudo-excitation method,equivalent linearization method and definite dynamic finite element method is presented.The parametric analyses of the single end-bearing pile structure are conducted in detail using this method.The results show that the parameters as inputting ground motion,pile length and soil modulu have obvious effect to seismic response of the system.The method could be employed to perform parametric analysis of pile-soil-structure interaction system subject with stochastic earthquake conveniently.

Abstract:The composite support technique of prestressed anchor arm and brad has been more and more widely used in foundation pit excavating.Taking a deep foundation excavation at Wangjiazhai,Zhengzhou city as an example,the computation model for the composite support technique of prestressed anchor arm and brad is established using FLAC numerical analysis method.The dynamic process of foundation excavating and support,considering the mutual effect between the support system and soil mass,is simulated.The destabilization of excavation on soil,the displacement change of foundation pit and inner force of brad and prestressed anchor are studied.The conclusions had some reference value for design and construction of the upport technique.

Abstract:Using finite element method,a FEM model of wind turbine tower considering soil-structure interaction simulated by the spring-damping element is proposed to investigate its dynamic response under multi-dimension seismic excitation in time domain.The updated Lagrange FEM formalism is adapted to discrete the equation and to use Newmark integral method to solve it step by step.Through this numeral analysis on the influence of P-Δ effect,the effects of soil-structure interaction and vertical seismic action on structure＇s dynamic property,the time-history response rule for the tower is studied with a real example.The result show that the effect of the soil-structure interaction on the seismic response of wind turbine tower structure is significate and should not be ignored.In line elastic range,the influence of vertical seismic loads and the P-Δ effect are not notable.

Abstract:Based on the field investigation result for the macroscopic anomalies appeared before and after Wenchuan MS8.0 earthquake on May 12,2008（from April 1,to July 13）in Longnan municipality and Zhouqu county of Gannan prefecture,Gansu province,through compilatio,analysis and selection for those data,the temporal and spatial distribution characteristics of the anomalies are researched.The result shows that amount of the macroscopic anomalies increased gradually with the time to event,and formed a peak just before the earthquake.In spatial more macroscopic anomalies distributed in higher earthquake intensity area.The relationship between the macroscopic anomalies and earthquake mechanism,as well as a possible effect for earthquake prediction are discussed also.

Abstract:Using the double difference earthquake location algorithm,we relocate more than 400 moderate and small earthquakes near the epicenter of 1668 Tancheng 8（1/2） earthquake since 1974.The relocated result shows that the modern moderate and small earthquakes were still concentrated in the Tancheng earthquake rupture zone.The strike of the bandy concentrated zone accords with that of the generating Anqiu-Juxian fault speculated by geological surveying.

Abstract:Using the primary components analysis method,six main parameters for indicating seismicity strenth such as frequency N（ML≥3.0）,b value,η value,A（b） value,Mf value,Ac-value are selected to analyse.The parameters are simplified effectively and a new synthetic index W for indicating seismicity strenth is obtained.It is found that the index W appeared obvious anomalies before Haicheng MS7.3 earthquake in 1975 and Xiuyan MS5.4 earthquake in Liaoning province,and returned after events.It is shown that the synthetic index W can reflect anomalous characterisitic of seiemicity well.

Abstract:The cycle process of tidal force of celestial body for Gaoling MS4.4 earthquake near Xi＇an city on Nov.5,2009 is calculated.According to this cycle the integrated multi-source temperature data are analyzed,and the abnormal temperature change images before the earthquake are gottern.The result indicates that the tidal force of celestial body has a triggering effect on fault activity.The temperature abnormal change can clearly reflect the procession of seismic fault activity： initial temperature rise→abnormally drop→return to baseline.It is shown that the effect of tidal force of celestial body on micro-earthquake activity is obvious and the temperature anomalies in micro-earthquakes are also clear.It is a good evidence for relationship between earthquake and thermal anomaly,and also for using geothermal anomaly to predict earthquake.

Abstract:Based on the digital observation data of borehole volume strain at Liuhe seismic station near Nanjing city,Jiangsu province,from 2003 to 2008,the main disturbance factors as atmospheric pressure and rainfall are analyzed,and the short-imminent abnormality characteristics of the volume strain for 3 earthquakes in the range of predict efficiency are discussed.The results show that the atmospheric pressure in short period affect strongly to value of strain with synchronization on time,the positive correlation coefficient is 0.6～0.7.The effect of rainfall to the strain is complicate,depends on the process,duration time and volume of rain.Only rainfall accumulate to certain volume the solid tide can be distorted.But we still found some features between rainfall and volume strain.The volume strain at Liuhe station had significant short-imminent abnormalies in 1～2 months before regional moderate-strong earthquakes.

Abstract:Based on the statistical and processing work for the peak acceleration data of Wenchuan MS8.0 earthquake in 2008,the statistical relationship between PGA and distance from the fault,PGA isogram and the 3-D acceleration diagrams in three directions are obtained.The results show that the peak acceleration attenuated slowly along the seismogenic fault,but attenuated rapidly in other directions,and the fastest decay appeared in the region within 100 km from the fault.High values of the peak acceleration commonly recorded in a narrow belt on both sides of the fault.Comparison of recorded values with values from the acceleration attenuation formula for west China shows that the latters are smaller and attenuate faster,it is consideredly related with the earthquake rupture mechanism and the tectonics.

Abstract:The genesis and mechanism of Wenchuan great earthquake are discussed agai.Based on the speech of some people who escaped by the earthquake in the epicentral area,Wenchuan earthquake was caused by deep gas protruding and explosion.The viewpoint mentioned above was proved by some other investigation and survey such as anomolies of satellite thermo-infrared surving and some macroscopic anormalies before the earthquake.The viewpoint of the relationship between earthquake and gas by some scholars in abroad and in home should be deeply concerned.

Abstract:GIPSY is a software from Jet Propulsion Laboratory in United State to post-process the GPS observations with high precision.It becomes more popular in GPS crustal deformation data process fields.As we known that GIPSY＇s source code is hard to obtain which aimed at the high precision GPS process and strong pertinences,so its user numbers is much less than GAMIT and Bernese.Meanwhile its preview version is difficult in installation that required basic LINUX knowledge.This paper intends to introduce the installation of GIPSY 5.0 to help the basic user to learn and use the software.