Editorial Office of Northwestern Seismological Journal
2000, 22(1):2-5.
Abstract:《西北地震学报》自1979年创刊以来,已经走过了20年的历程.多年来,《西北地震学报》坚持办刊宗旨,贯彻双百方针,及时报道西北地区及全国地震科研工作的新成果、新进展,为发展我国的地震科学事业,促进国内外学术交流以及在培养人才方面做出了积极的贡献.
QIN Bao yan , ZHANG Yuan sheng
2000, 22(1):6-10.
Abstract:Based on the comprehensive model,the relation between vP/vS anomalous area evolution characteristics,positive or negative,before some moderate or strong earthquakes and main earthquake location in Gansu and its neighborhood is discussed by using convergent method.The results show that main shock often occurs on the boundary between negative and positive anomalous areas,as well as in the crossing area of different character velocity ratio anomalies.Moreover,it is discovered that there is a close relation between wave velocity ratio anomaly and the movement of adjustment element.The convergent method of wave velocity ratio spatial anomaly boundary has universal significance for predicting earthquake location.
2000, 22(1):11-16.
Abstract:The fundamental principle and methods of probabilistic seismic hazard analysis based on the Poisson's model and the characteristic earthquake model depending on time are discussed.The comparison between two models and PGA maps of middle-eastern Qilian area are made.The results show that probabilistic seismic hazard analysis by characteristic earthquake model depending on time is more rational in theory than that by the Poisson's model.
YAO Lan-yu , NIE Yong-an , ZHAO Gen-mo
2000, 22(1):17-24.
Abstract:A complete suit of closely analytical expressions of stress field is presented for the strike-slip shear fault with an arbitrary dip angle in a semi-infinite medium.Checking and reviewing the analytical expressions of stress field by other researchers,closely mathematical reasoning for the expressions is done again,thus this suit of expressions has become more perfect and reliable.
XU Xiu-deng , ZHANG Hang-cai , LI Gui-da
2000, 22(1):25-28.
Abstract:Analysing the data of the total atmosphere temperature,it is discovered that anomalous increase of atmosphere temperature a few days before the Zhangbei MS6.2 earthquake on Jan.10,1998 in epicentral region and its surrounding areas is a kind of impending earthquake precursor.Space distribution of anomalies shows that epicentre of the earthquake is in strong anomaly area which is surrounded by weak anomaly area;the earthquake may be caused by extension of Zhangjiakou -Beijing -Penglai fault of NW towards the west and related to activity of Shangyi -Duolun NE fault etc.at the same time.Development of the total temperature isopleths reflects summarily the process of the accumulation,the expansion and the release of strain.
WANG Ji-hua , LIN Yuan-wu , GAO Song-sheng , LIU Cheng-long
2000, 22(1):29-33.
Abstract:The relationship between the characteristics of change of CO2 in fault product gas in Houhaoyao,Huailai county in 1998 and influence factors,such as geotemperature and rainfall is analysed.The observation values of CO2 in fault product gas and geotemperature change generally in synchronism.The reason of negative correlation between change of CO2 and geotemperature is discussed.The negative correlation from March to early in June,1998 resulted from recovery process of CO2 observation values from high to low after the Zhangbei-Shangyi MS6.2 earthquake.The negative correlation from the middle of June to the middle of Sept.,1998 resulted from excessive rainfall during this period.The anomalous characteristics of CO2 before and after the Xilinhaote MS5.2 earthquake,Inner Mongolia on January 29,1999 and the Zhangbei MS5.6 strong aftershock on March 11,1999 are introduced.
2000, 22(1):34-40.
Abstract:The medium-short term prediction and monitor process of the Lijiang MS7 earthquake on Feb.3,1996 of Yunnan province is introduced.Seismicity trend before the earthquake was forecasted according to seismicity feature and commensurable characteristics of strong earthquake activities of Sichuan and Yunnan areas.Since Oct.,1995,a lot of kinds of the anomalies with large amplitude,such as radon and CO2 contents in groundwater and groundwater level etc.synchronized in a wide range of western Yunnan,especially along Zhongdian -Nanjian seismic area.The characteristics of these short-term anomalies are introduced and analysed.According to the anomalous characteristics and distribution of the anomalies,as well as seismicity indices,the author thought that a M 5~6 earthquake may occur in Zhongdian -Lijiang -Jianchuan -Huaping zone the end of Feb.,1996 before and had presented a written prediction to the government of Dali prefecture.
WANG Shu ming , LIN Chang you , YANG Chang fu , CHEN Jun ying , LUO Dong shan , LU Fu lin
2000, 22(1):41-46.
Abstract:Based on two dimensional digital simulation of the frequency electromagnetic sounding with electric dipole supply,the variation characters and static displacement of five kinds of apparent resistivity in wave area are theoretically studied,and the effects of surface local lateral inhomogeneities on distortion of apparent resistivity curves are qualitatively analysed.
DONG Zhi-ping , HE Wen-gui , DAI Hua-guang
2000, 22(1):47-47.
Abstract:1954年山丹地震遗留至今的破裂带主要有2条:包代河至黑山头为主破裂带,长约16 km;独峰顶至坡拉麻顶为次级破裂带,断续分布长约10 km.2条破裂带走向均为NW,近于平行,二者相距约6 km,分别由地震断层、崩塌和地裂缝等构成.
2000, 22(1):48-53.
Abstract:Strain disturbance εi values before 5 strong earthquakes (ML ≥ 6.5) in Yunnan region have been calculated and analyzed.The results indicate that about 5~8 years before earthquake εi values of earthquakes with magnitude of normalized 4 show obviously the abnormal high value;The εi values are lower in the coming epicenter,but increase in periphery of the epicenter,developing the gap;The εi values show a tendency from a random and scattered distribution to converging towards epicenter and strengthening.
WU Fu-chun , DUAN Feng , KE Chang-an , ZHANG Chun-sheng , DONG Xing-hong
2000, 22(1):54-58.
Abstract:Some characteristics of the Jingyang MS4.8 earthquake in 1998 are analysed.The results show that the earthquake is during weaker seismicity in Guanzhong,Shaanxi.Sequence of the earthquake is isolated type and differs from sequences of greater part of historic strong earthquakes in Guanzhong area which are mainshock-aftershock type.The sequence type of the earthquake is very scarce in Chinese continent.The focal mechanism solution of the earthquake shows that the seismogenic fault is left-lateral slip one,the principal stress orientation is NE~SW and identical with the direction of regional stress field of northern China.
2000, 22(1):59-62.
Abstract:Relationship between characteristic of high frequency and low intensity of M ≥ 6 earthquake activity of Chinese continent and M ≥ 7 earthquakes of China and the whole world is ana-lysed.The results show that the characteristic appeared during the weak activity of M ≥ 7 earthquakes of the whole world.There is a very fair possibility of M ≥ 7 earthquakes to occur in the vicinity of Taiwan province one year after the characteristic and in Chinese continent two years after the characteristic.
MA Wen jing , ZHANG Xiao qing , ZHANG Xiao dong
2000, 22(1):63-68.
Abstract:The earthquake magnitude and energy sequence are fitted by using mathematical model based on mean generation function and prediction for medium term earthquake trend of next three years are made.The method has following features:couple score criterion is applied for raising the fitting accuracy and rate;and balance between numerical prediction and trend prediction is considers;the multistage fitting of difference sequence for raising accuracy and speed of fitting is used.Besides,the optimum period of the time sequence is given.The earthquake trend of Chinese continent in next 1~3 years is forecasted by using the method.
LIU Wei-he , WANG Zhen-ya , XU Qin
2000, 22(1):69-74.
Abstract:Based on the historical seismicity data,correlation between seismic activity of deep seismic area in northeastern China and that of Chinese continent is analyzed and studied.The result shows that seismic activity in seismicity peak period of Chinese continent is related to MS ≥ 6.5 deep focus earthquakes.During three years after deep focus earthquake occurred,seismicity of Chinese continent obviously strengthened and strong earthquakes may occur along 40° N and north-south seismic zone.
ZHAN Zhi-jia , GAO Jin-tian , ZHAO Cong-li , ZHANG Hong-li , SHEN Wen-zhi
2000, 22(1):75-79.
Abstract:The G-856 proton precession magnetometer is characterized by high accuracy,intelligence and combined application with computer.It is suitable for seismomagnetic precursor observation and earthquake prediction research.Main property of the magnetometer and results of its property test are introduced.The optimum seismomagnetic observation should be to mainly observe geomagnetic total intensity with proton magnetometer and combine to observe geomagnetic three components and geomagnetic shortperiod variations.
2000, 22(1):80-83.
Abstract:The dynamic model forecasting the origin time of earthquake is established by using the grey control system and choosing MS5.0 seismic sequences as samples.The best model is chosen to forecast moderate and strong earthquakes of the juncture of Shanxi,Hebei and Inner Mongolia.Trend of strong earthquakes of the area is forecasted by using the models.
SHI Yu cheng , CAI Hong wei , XU Hui ping , LIU Hong mei
2000, 22(1):84-90.
Abstract:Taking Mogao grotto as example,the seismic resistance characteristics of retain wall type grotto is discussed.Methods for the seismic stability evaluation of surrounding rock and auxiliary structures of grottoes are studied.It is concluded that the method of dynamic analysis can be mainly used in seismic response analysis for large scale grottoes and its auxiliary structures,at the same time,results of pseudo static analysis have to be used as reference.Furthermore,some thoughts and methods of evaluating seismic resistance ability of grottos are put forward.
HE Wen gui , LIU Bai chi , YUAN Dao yang , YANG Ming
2000, 22(1):91-98.
Abstract:Based on data of field investigation in major area of Lenglongling fault zone,geometric characteristics and slip rate of the fault zone are studied.The results show that the fault zone is an active one in Holocene and consists of a group of secondary faults.According to its total characteristic,the fault zone can be divided into 3 segments.The average left lateral horizontal slip rates of the fault zone since middle Pleistocene are calculated.The horizontal slip rate in middle Pleistocene is 2.14~4.64 mm/a,the rate in Epipleistocene is 2.86~4.07 mm/a,the rate in Holocene is 3.35~4.62 mm/a.The vertical slip rate is 0.38 mm/a since Holocene.
XING Xi-chun , WANG Zheng-liang , MAO Juan , SHAO Hui-cheng
2000, 22(1):99-101.
Abstract:Anomalous changes of deformation data observed by Jingyang station before and after the Jingyang MS4.8 earthquake on Jan.5,1998 are analyzed.Medium and short-term anomalies before the earthquake and obvious postseismic effect in the data are discovered.
CHEN Shao-guang , PAN Wei-shuang , WEI Ru-qing
2000, 22(1):102-104.
Abstract:Anomalous character of radon content in Liaogu-1 well before the Ningjin MS5.8 earthquake on November 9,1981 and the Heze MS5.9 earthquake on November 7,1983 are analysed.Radon content in the well has gone up by a wide margin 5~10 days before the earthquakes.The earthquakes occurred during radon content dropping.Therefore,the anomalous changes of radon content of the well can be regarded as a short-impending prediction index.
Sopyright:China Earthquake Engineering Journal