2002, 24(3):193-198,219.
Abstract:The geoelectrical fields induced by oscillating dipole source are numerically simulated in different heterogeneous models. The results show that for the model of ordinary layered media it is impossible to observe such electrical signals on earth surface. It is found that the surface field can be enhanced 2 or 3 orders if these is high conductive fault in the layered model. The surface abnormal electrical signals of ordinary electric structure is about several mV/km or less, however it could reach hundreds mV/km in special electrical structure.It is deserved to point out that the area of strongest abnormal signals is not over the epicenter, but is in some points of fault.This means the heterogeneity of electric structure is advantageous to detect abnormal electrical signals, on the other hand, it leads to the complex phenomena of abnormal electrical signals distribution on surface.
WANG Xiao-qiang , WANG Qi , CHENG Rui-zhong , QIAO Xue-jun , LI Jie , ZHANG Yong-gang , HAI Li
2002, 24(3):199-207.
Abstract:Jiashi and its adjacent region in Xinjiang, China is one of the areas that are effected by plate movement strongly in China mainland, and it is also one of the areas with the strongest seismic activity at present. In order to study the crustal movement features, a large-ranged, high-precision GPS monito ring network is established, which consists of mo re than 40 points. The data surveying from 1994 to 2000 are processed by using GIPSY-OA-SIS Ⅱsoftware with presision of baseline between 10-8~10-9. The image of crustal deformation ratio shows that recent tectonic movement in the western segment of Tianshan is crustal shortening and deformation in NS indirection, about 20 mm/y r, and the compression of India plate to Eurasia plate is the main dynamic source. The movement ratios are different in places, and the mean strain rate is 0.04×10-6/a.
ZHANG Dong-li , WANG Lan-min , WANG Yu-hua
2002, 24(3):208-214.
Abstract:In the study, the FEM (Finite -Element Method)are used to predict the seismic subsidence, and the relations, among the subsidence characteristic of loess ground and the site, the foundations, the soil dynamic property, can be studied quantitatively. As a method, it can provide the theoretical laws for seismic design and seismic resistance. At the same time, loess dynamics used in earthquake engineering is developed greatly.
JIANG Jian-ping , ZHANG Yang-song , GAO Guang-yun , LUO Guo-yu
2002, 24(3):215-219.
Abstract:The quaternary fault in soilmass, as a kind of soilmass structure plane, become a new research field in geotechnical engineering. It is found by researching the characteristics of fault plane in soilmass that fault active connected with tick-slip movement when R <80%, and with steady state slip movement when R >80%.
2002, 24(3):220-224,229.
Abstract:Based on the GB50218-94 classification of rockmass quality and deformation data of Jinchuan experimental tunnel, a new method of classification by using the artificial nervous network is established. The classification of rockmass quality of tunnel of 1218m in Jinchuan mining area is made by using the method, and result shows that it is effective.
DONG Zhi-ping , HE Wen-gui , DAI Hua-g uang
2002, 24(3):225-229.
Abstract:The Baodaihe fault is the main seismic rupture zone of 1954 Shandan earthquake(M=7¼), which shows rig ht-lateral strike slip movement with a small portion of dip-slip component. The fault is about 4.5 km long. For the first time, three paleoearthquake events can be identified in the trench cross the Baodaihe fault. According to the 1 C 4 and TL age date of the strata in the trench, the first event occurred later than 3 120±250 a B. P., the second one took place approximately 2 500±1 70 a B. P., and the third one occurred later than 2 150±170 a B. P., the recurrence interral of great earthquake alo ng the fault is approximately 350~700 years.
2002, 24(3):230-235.
Abstract:The spatial and tempo ral activity characteristics of strong earthquakes around Ordos massif (34°~42° N, 104.5°~114.5° E)are studied by using the earthquake data(MS ≥ 6.0) from A. D. 400 to 2000. The result shows that there are characteristics of active in stages, the spatial and temporal order in migration, filling seismic gaps and epicenters repeat, distribution of strong earthquakes be equal in distance. The seismic risk analysis shows that the possible places of next MS 7 earthquake are both ends on Yinshan seismic zone in north margin of Ordos massif.
2002, 24(3):236-240.
Abstract:The focal mechanism of MS 5.4 earthquake on June 1, 1996, in the Tianzhu pull-apart basin of western Haiyuan fault is studied. The seismogenic fault of the event is determined by using the precisely locating aftershocks, which recorded by the local digital seismic network.The result shows that the earthquake caused by the fracture of a nearly SN direction small fault, which perpendicular to western Haiyuan main fault, in the Tianzhu basin. The seismic risk along western Haiyuan fault is discussed on the basis of the fracture model and the condition of stress concentration in the area.
2002, 24(3):241-246.
Abstract:The correlation of earthquakes with MS ≥ 7.0 in interior Tibet plateau and Burma transform tectonic region, southwestern of Yongnan region is studied.The results show that the spatio-temporal co rrelation is among earthquake very obvious in Tibet plateau and its adjacent regions. The main features of seismicity are cluster in temporal, migration in space and order in migratory route. In each cluster, usually the events first occurred in Burma transform tectonic region and southwestern of Yongnan, then migrate to the Southnorthern Seismic Belt and interior Tibet along two routes, with complete pattern.
2002, 24(3):247-250.
Abstract:How to apply Hurst exponent of seismic frequency to predicting earthquake in Jiangsu province and its adjacent area is studied. It indicate that the Rvalue derived from retrospective prediction test to the earthquakes (MS ≥ 5.0)in the area since 1970 is 0.365, and 81.8%of earthquakes which are predicted correctly take place in one year after anomoly start. Therefore it can be used for predicting earthquake in Jiangsu province and its adjacent area.
2002, 24(3):251-256,261.
Abstract:The data of radon and other items of deep well groundwater in Qing 6 well, Yumen city and Jing 3 well, Jingchuan county, Gansu province, are processed by multiple regression, correlation and univatent difference analysis to remove interference factor. The results show that there are obvious anomalies in data of both wells before Sunan MS5.4, Tuolai MS6.0 and Lixian MS5.1 earthquakes. The reflecting and predicting earthquake ability are evaluated.
GENG Jie , ZHOU Bin , ZHANG Zhao-dong
2002, 24(3):257-261.
Abstract:The barometric pressure efficiency and interrelation coefficient of groundwater level in five deep wells are calculated by using high-order difference method and the best interrelation result between them is optimized. The anomalous variations on two curves are obtained before the Heze 5.9 earthquake in 1983 and Lulong 5.3 earthquake in 1982. The result indicats that anomalous information obtained from the method is feasible, and can be used as short -impending anomaly before moderate and strong earthquakes.
ZHANG Zi-guang , ZHANG Su-xin , ZHENG Yun-zhen , WANG He-sheng
2002, 24(3):262-266.
Abstract:The curves of recorded seismic wave on groundwater level in Shanxi water 2 and Yue 42 wells, in Tangshan city, Hebei province, are contrasted. Both wells locate in the same geological unit and same water-bearing bed, with same water level dynamic style, but have very different abilities of recording seismic wave. The mechanism of the difference in two wells is analysed from the structure of wells and the property of seismic surface wave. The result shows that the inherent period of well hole is the first important condition for influencing the ability of recording seismic wave of groundwater level in well.
REN Xie-mei , MA He-qing , ZHAO Zhi-jun , XIE Xiao-fen
2002, 24(3):267-272.
Abstract:Through analysising the seismicity data before ML ≥ 5.0 earthquakes in Ningxia and its adjacent areas since 1965, it is found that there mostly is the characteristics of enhancement of moderate earthquakes before ML ≥ 5.0 earthquakes. In A part of the study area, the probability for occurrence of ML ≥ 5.0 earthquake is 0.71 after anomaly of the enhancement of moderate earthquakes in 7 months; and it is 0.60 in 3 years in B part. The probability that earthquake locats near the outer linked lines of all earthquakes in one enhancement of moderate earthquakes is 0.79. Its R -value is 0.75. So the enhancement of moderate earthquakes can be a middle period prediction method for M ≥ 5 earthquake in this region.
XIAO Li-zhu , LIU Xiao-feng , ZHENG Wei-ping
2002, 24(3):273-277.
Abstract:The earthquake of MS 5.3 occrred at the Qiqing town Sunan county in Gansu province has been systematicaly analyzed. The features of seismicity and the characteristics of anomalies of before the earthquake are studied. The earthquake sequences is mainshock type. The value of b is 0.38;h value is 0.9; and the energy release of mainshock is 99. 1 percent of all earthquake sequences. The characteristics of the event sequence is high strong and low frequency. The distribution of remainshock is more concentrated and the direction is N E.
2002, 24(3):278-282.
Abstract:Some errors in the paper "Manifest expressions of three basic parameters in Biot theory" written by the author him self (Northwestern Seismological Journal, Vol. 19, No. 4, 1997)are corrected. These errors do not coincide with what Prof. Ding discussed in the paper "On mistakes about ‘Manifest expressions of three basic parameters in Biot theory’"(Northwestern Seismological Journal, Vol. 20,No. 4, 1998). Meanwhile same concept errors in Prof. Ding's paper are discussed.
XIE Zhi , LIU Yao-xing , HU Wei-jian , XIE Jian-jian , MA Jun-ling , ZHAO Hui
2002, 24(3):283-286.
Abstract:The focal mechanisms of 52ML ≥ 3.5 earthquakes in Henan and its adjacent region from 1965 to 2000 are given. The results indicate that the strikes of the two nodal planes of these focal mechanisms are NNE and NWW repectively; most of the principal compressive stress axes P strike NEE and principal extensive stress axes T strike NNW; the seismo-tectonics mainly are strike-slip faults. The direction of P axes change from tumble into identity before moderate earthquakes.
2002, 24(3):287-287.
Abstract:人类活动排放二氧化碳气体使全球增温,从而引起极冰融化、海水淹没海边城市以及暴洪和疾病的增加.因而全球增温已成为人们非常关注的问题.
Sopyright:China Earthquake Engineering Journal