• Volume 31,Issue 4,2009 Table of Contents
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    • Influence of Seismic Source Mechanism and Fault Property on  Near-field Strong Ground Motion

      2009, 31(4):311-318.

      Abstract (814) HTML (0) PDF 1.12 M (1115) Comment (0) Favorites

      Abstract:Based on the simulation of strong ground motion at near-field by numerical Green function method, take the seismic source with heterogeneous dislocation distribution and crustal velocity structures in 1994 Northridge earthquake as computing model, two studies are proceeded: (1) For vertical strike fault(the dip is 90°), we simulate the strong ground motion by means of unilateral rupture and bilateral rupture, and analyze the influence on two major strong ground motion characters--the rupture directivity effect and hanging wall effect. (2) For oblique fault, (the dip is 45°), we compute the strong ground motion of normal fault, thrust fault and strike fault with unilateral rupture mode, and analyze the influence on rupture directivity effect and hanging wall effect. The results reveal that in near field, the rupture directivity effect and hang- ing wall effect are obviously influenced by different fault properties and seismic source modes. The seismic source modes effect the ground motion peak values and vectors distribution directly. In near field, whatever vertical fault or inclined fault, the ground motion intensity ahead of rup-ture directivity is stronger than that of behind rupture directivity, which indicats that the wavefront are compressed during propagation. The hanging wall effect can be described by simulation results of inclined fault very well. The maximum values of NS component and UP component appear on hanging wall near the fault and the EW component maximum values are dissymmetry on both sides along fault. The peak values caused by thrust fault are greater than by strike fault and normal fault, the values cause by normal fault are the smallest of all.

    • Study on Shaking Table Test for Seismic Response of Pile  Foundation of Bridges at the Permafrost Regions

      2009, 31(4):319-326.

      Abstract (853) HTML (0) PDF 505.10 K (767) Comment (0) Favorites

      Abstract:Based on the research project of pile foundation of the Qingshui River Bridge, which is a typical engineering named by "bridge instead of road" and locates at high temperature and instability permafrost region along the Qinghai--Tibet Railway. Under seismic dynamic loading, the shaking table test for the scale model of the piles is carried out when the soil temperature around model piles is below 0℃. The interaction between piles and frozen soil under seismic loading is researched, and the characteristics of seismic response of the pile structure are analyzed. Moreover, that the effect law of dynamic loading response of the piles on temperature and strain around piles is achieved, and the stability of the pile foundation of bridges at high temperature and instability permafrost region is evaluated as well.

    • Application of MALAB Software and ALOS Remote Sensing Imagine to Automatic Recognition of Earthquake Damage Building: Take Dujiangyan Urban As an Example

      2009, 31(4):327-332.

      Abstract (926) HTML (0) PDF 507.45 K (1009) Comment (0) Favorites

      Abstract:Remote sensing technology can provide a reliable scientific basis to the aspect of automatic recognition of earthquake damage building in the rapid evaluation and rescue decision. In this paper, based on the data of ALOS remote sensing imagine on Dujiangyan urban area after 5 ·12 Wenchuan great earthquake, taking the imagine characters of earthquake damage buildings from high resolution remote sensing as the starting point, using MATLAB software to processings of gray enhancemen, mathematic morphology reconstruction, bridge and filling, the damage buildings are automatically recognited. The result shows that it can accurately extract the earthquake damage building information by using abundant textural property and spatial structure information of ALOS remote sensing imagine and MATLAB's advantages in mathematics morphology.

    • The Surface Rupture of the Ms8.0 Wenchuan Earthquake on the  Northern Segment of Central Fault

      2009, 31(4):333-338,348.

      Abstract (762) HTML (0) PDF 496.22 K (1004) Comment (0) Favorites

      Abstract:The Surface rupture of Beichuan--Nanba--Linanshi Fault, which is the northern seg- ment of Longmenshan tectonic belt is studied. Observation at Huangjiaba,Guixi, Pingtong, Nanba and Shikanzi suggests that the surface ruptures on this segment spread continuously along the trend of the fault with N45°-65°E in general. The rate of vertical offset and horizontal offset become small from Huangjiaba(2.8:1) to Shikanzi {0.9:1). Features of surface rupture indicate that the fault movement is thrusts with dextral strike-slip. Distribution of aftershocks indicates that the area between Beichuan--Nanba--Linanshi Fault and Qingchuan Fault probably have a buried active fault.

    • Characteristics of the Surface Rupture of the Ms 8.0 Wenchuan  Earthquake on the Epicenter, Yingxiu Area

      2009, 31(4):339-343.

      Abstract (741) HTML (0) PDF 322.98 K (808) Comment (0) Favorites

      Abstract:On the epicenter area of Wenchuan great earthquake in 2008, Yingxiu town, Sichuan province, the earthquake caused a number of surface rupture, such as road bending deformation, fault scarps and new deformation at "the groove in the slope", the total length of zone is about 300 meters. Using total station and GPS, at 4 rupture points the displacement were measured, and the vertical and level components of offset were analyzed quantitatively, as well as the ratio between them. The result shows that the motion of seismogenic Yingxiu--Beichuan fault is mainly thrust with some right-lateral strike slip, the thrust component is greater than the strike-slip component at Yingxiu area. Comparing the surface rupture before and after the event at same place, it is revealed that the earthquake rupture is anastomose with the active location of Yingxiu --Beichuan fault during recent geology history, which means that the fault scarp about 40 m on the terrace Ⅳ of Mingjiang river maybe is the results of number of major earthquakes in geological history.

    • Shaking Table Test Study on Damping Performance of  Steel Ball-bearing for Grid Structure

      2009, 31(4):344-348.

      Abstract (718) HTML (0) PDF 316.23 K (947) Comment (0) Favorites

      Abstract:A new type of steel ball--bearing is presented to match the stress features and requirements of grid structures. According to the similarity principle, four scale models of grid steel ball-bearing were made and shaking table test was carried out to systematically study the isolation and damping performance of them under different seismic inputs. The results show that the bearings can effectively isolate the input of seismic vibration into upper structure and have better damping and energy dissipation ability.

    • Anomalous Change Features of Resistivity before the Wenchuan M8.0 Earthquake and Other Large Earthquake in China

      2009, 31(4):349-354,384.

      Abstract (745) HTML (0) PDF 397.59 K (1065) Comment (0) Favorites

      Abstract:The anomalous change features of resistivity in the monitoring stations, which are loca- ted near or far from the epicenter of Wenchuan M8.0 earthquake in 2008, are analyzed. There were intermediate-term anomalies for more than one year stations which are less than 400 km from the epicenter, at Pixian, Ganzi, Mianning and Wudu and short and imminent-term anomalies even existed at Lanzhou and Tianshui stations which are far from the epicenter. Also the data of electrical resistivity in past several tens years for 9 large earthquakes with M≥7.0 are summa- rized. The result shows that most anomalous resistivity changes before large earthquake are negative and the value curves are decline, earthquake often occur near the position of extremum or in resuming process. The anomalies can be found at most stations near epicenter, lasting for more than one year with annual rariation disappear. The short and imminent-term change can be ohserved also. For far stations, only some have the anomaly, mainly are short and imminent, and event occurs in or after resuming process.

    • Focal Mechanism Inverssion of Partial earthquakes in Gansu Province, 2007

      2009, 31(4):355-357.

      Abstract (748) HTML (0) PDF 177.59 K (983) Comment (0) Favorites

      Abstract:In 2007, total 43 ML〉3. 0 earthquake were recorded in Gansu province. Among them 17 events are selected for focal mechanism inversion, using the method of seismic moment tensor inversion with P wave onset. The basic parameters of best double-couple are gotten. Based on the result, the earthquake tectonic backgrounds and mechanism in some areas of Gansu province are discussed. The result could afford reference to earthquake prediction in the region.

    • The Meaning of Moderate Seismic Activity Quiet to Strong Earthquakes  in Hetao Belt and Fenwei Belt

      2009, 31(4):358-362,366.

      Abstract (742) HTML (0) PDF 414.88 K (957) Comment (0) Favorites

      Abstract:The interval days between two earthquakes in the Hetao and Fenwei seismic belts are statistical analyzed. The result shows that there were obvious moderate seismic activity quiet phenomena before strong earthquakes in large range in two belts, especially in Fenwei belt. A- mong 5 Ms≥6.0 earthquakes since 1976, 4 events occurred at the end of the seismicity abnormal quiet period or in the quiet course. Now the moderate seismicity quiet time has surpassed the biggest time interval in history record, so there is possibility of strong earthquake in Hetao belt and Zhangbo belt in future.

    • Analysis on Sand Seismic Liquefaction Prediction Based  on the Support Vector Machine

      2009, 31(4):363-366.

      Abstract (766) HTML (0) PDF 238.03 K (979) Comment (0) Favorites

      Abstract:Considering the main factors with important influence on sand seismic liquefaction, the support vector machine (SVM) model is established, which includes seven indexes such as earthquake magnitude, SPT counts, relative density, soil layer depth, time history of earthquake, peak ground acceleration and epicenter distance. Taking surving data as samples for training and learn- ing, some functions are obtained in identification of sand sample. It is shown that the identification model of SVM analysis is an effective method to predict sand liquefaction with high prediction accuracy and could be used in practice.

    • Research on Relationship between the Ground Deformation  and Dynamic Groundwater Level in Handan, Hebei

      2009, 31(4):367-373.

      Abstract (796) HTML (0) PDF 414.16 K (753) Comment (0) Favorites

      Abstract:Based on the geological structure of Handan area of Hebei province and the observation date more than 20 years, the normal and abnormal dynamic variations of ground deformation and groundwater as well as their relationship are analyzed. The main two control factors for the ground deformation in Handan area are Taihang mountains rising at west and the continual settlement movement of the northern China plain at east, which caused deformation slan to southeast. But after regional periodic heavy rainfall the deformation slan to northwest, because of the difference of geological structure. Both are normal variations. The anomalies in the deformation and groundwater level are extructed by effective methods, the result indicats that there was a good correspondence between a part of anomalies of opposing northwest slant and northern China plain moderate and strong earthquakes. So it should not be set dowe as interference that the ground lean with a wide and periodic hesvy rainfall. In a sence, it is a factor from out side to induce ground deformation and earthquake. So we shoule attach great importance to the factor.

    • Characteristics of Seismicity Anomalies before Ms 8.1 Earthquake  at the WeSt to Kunlun Mountain Pass

      2009, 31(4):374-379.

      Abstract (744) HTML (0) PDF 379.35 K (921) Comment (0) Favorites

      Abstract:The seismicity anomalies before Ms 8.1 earthquake at the west to Kunlun Mountain pass in 2001 are studied by using the methods of tracing dynamic seismicity evolution patterns, the parameters time scanning and earthquake swarm determination, which are all commonly used in earthquake prediction. The results show that the seismicity anomalies were obviously in order, the anomalies for earthquake gaps, belts and groups appeared in same period. It is considere that the evolution of earthquake gaps patterns is helpful to study the large earthquake prepare field, the earthquake swarm are precursory reflect of muir-points stress releasing before large earthquake, and large earthquake could be predicted in middle and short-term through synthesis analysis to the seismicity parameters time scanning.

    • Corresponding Relation between Kalaqin Earthquake Swarms and  Moderate-strong Earthquakes in the Around Areas

      2009, 31(4):380-384.

      Abstract (752) HTML (0) PDF 309.10 K (929) Comment (0) Favorites

      Abstract:Several typical earthquake swarms occurred in Kalaqin region, Inner mongolia, in history, and a new one occurred here from Aug. 19 to Sept. 14, 2008. In this paper, the historical earthquake swarms in this area and the relationship with moderate-strong earthquakes in around areas are analyzed. The result shows that the earthquake swarms activities in Kalaqin area have some corresponding relation with the moderate-strong earthquakes in around areas. So the new events have important foretell hint to forecast moderate-strong earthquake in the region.

    • High-velocity Rock Frictional Experiment and Physical Process of Earthquake

      2009, 31(4):385-392.

      Abstract (980) HTML (0) PDF 591.10 K (1038) Comment (0) Favorites

      Abstract:The progress of research on high-velocity rock frictional experiments in China and abroad in last 20 years is reviewed briefly. The progress in this field is mainly presented at following aspects. (a) The development of experimental technique in high-velocity rock friction has realized the simulation on earthquake process with high slip rate and large displacement be- come realistic. (b) The results reveal the mechanical properties of rocks and fault gouges under seismic slip velocity, which promotes our understanding on the weakening mechanism of fault slip, the critical slip distance and the earthquake process. (c) The experiments have made important progress in the cause of pseudotachylite and suggested other possible geological evidences left by seismic fault slip, which may offer new ideas and information for studying fault frictional properties and physical process of earthquake. It is prospected that the further study in high-velocity rock frictional experiment will focus on following aspects: developing high-velocity rock friction apparatus with temperature and pore pressure systems and investigating the high-velocity frictional properties of rocks and fault gouges under hydrothermal condition, studying mechanism of fault slip and earthquake by combining laboratory experiment and seismic data analysis, and seeking after geological records of seismic slip by combining laboratory experiment and field geological investigation.

    • Research Progress in Experimentation Areas of Seismomagnetic Measurement

      2009, 31(4):393-396,402.

      Abstract (752) HTML (0) PDF 332.55 K (975) Comment (0) Favorites

      Abstract:From the respects of current situation, processing of surveying data, method of model computing and surveying results, the research progress on experimentation areas of seismomagnetic measurement in China are introduced. Through exploring research, the important significance of the experimentation areas of seismomagnetic measurement is analyzed, and the development prospect of it is looked forward.

    • Research and Ponderation Over the Efficiency of Annual Seismic  Prediction for Wuqia--Kashi Region in Xinjiang

      2009, 31(4):397-402.

      Abstract (815) HTML (0) PDF 382.95 K (1003) Comment (0) Favorites

      Abstract:Based on the predictive results of annual seismic risk regions in Xinjiang since 1973, the efficiency in different phases for Wuqia Kashi region is studied mainly, and the active characteristics of earthquake with magnitude Ms≥6.0 since 1900 and also the magnitude Ms≥75.5 from 1972 to 2008 are analyzed. It is considered that the earthquake prediction have not obtained finer results in the Wuqia Kashi annual seismic risk regions, and the reason was lack of correct recogninon to the seismic active regulations in this region. At last, according to the history earthquake activity characteristics, we predict that Wuqia Kashi region will probably start an active period since the end of 2008, and it may be carry out an annual seismic risk area continually.

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