CHEN Wen-bin , XU Xi-wei , ZHANG Zhi-jian , CHEN Yong-ming , HE Wen-gui , LIU Hong-chun , DAI Hua-guang , Lu Ming
2001, 23(4):313-317.
Abstract:Preparatory field investigation reveals that the surface deformation zone of the Qinghai-Xinjiang MS 8.1 earthquake on November 14, 2001 distributes along the south foot of Kunlunshan mountains, and may terminate at the Bugedabanfeng as the western end while the eastern end is tracked down at the point 70 km east from the Qinghai-Xizang Raod.The total length of the deformation zone reaches 350 km.The deformation shows clear strike-slip feature and the maximum horizontal offset is found to be 6 m.It was temporarily determined that the macro-epicenter is 30 km east from the Kusaihu lake, and the intensity in the macro-epicenter is Ⅺ.It's suggested that the earthquake be named as Kusai hu earthquake.
2001, 23(4):318-329,338.
Abstract:The basic formula of pseudo-spectral method are derived for simulating inhomogeneous anisotropic elastic waves field.The boundary modifying equations of characteristic variables method are derived thoroughly which have been presented by previous authors separately, and the explicit formula of 3D and 2D problems of solid and liquid media are given.2.5D elasticwave field of two models are simulated,moreover, the polarization and time delay of S wave splitting are discussed in detail.
2001, 23(4):330-338.
Abstract:The recurrence probabilities of earthquakes for faults in future in mid-eastern Qilianshan area are analyzed by using quantitative data for the active faults which are obtained by the authors and other men of learning in recent years and the probability model depending on time,based on improving the precisions of the quantitative data.The results are as follows:(1)The recurrence probabilities of strong earthquake on Jinqiang river and Maomaoshan segments of Laohushan-Maomaoshan fault are higher.Except the two segments,the probabilities of MS ≥ 7.0 earthquakes on faults in the area are nearly zero in future 100 years.(2)The probabilities of strong earthquakes on the two segments are 15.76%, 29.03% and 15. 33%,28.41%respectively and the probabilities of the two segments together are 28.67%and 49.19% respectively in future 10 and 20 years.Infuture 50 years,the probability of MS7.5 earthquake on the two segments together is 81.79%.(3)The probability of MS ≥ 7.0 earthquake on Maxianshan fault in future 50 years is 19.87%.
WANG Wei , SONG Xian-yue , WANG Zheng-zheng
2001, 23(4):339-345.
Abstract:The seismicity data of moderate or small earthquakes in North China are used to space scanning of seismic inhomogeneous degree GL-value.Characteristics of mid-short term anomalous changes of the value before mid-strong earthquakes in the region are studied.The result shows that the mid-term anomalous area of the GL -value obviously contracts or disappears in mid-short term of about 1 year before moderate or strong earthquakes in generally.The anomalous area appears again in several months before some earthquakes.Some problems about mid-short term prediction by using the GL-value are also discussed.
2001, 23(4):346-353.
Abstract:The Helmholtz's equations and boundary conditions are set up for study on electrical field induced by oscillation dipole source in layered media from the Maxwell's equations and introducing the Hertz electric vector potential.The equations for calculation of electrical field on surface of the layered media are obtained.The integral equations for calculation of electric field on the surface of the layered media with a fault are derived from the Maxwell's equations and introducing the Green's tensor.The equations can be used in numerical simulation of geoelectric field change on earth surface.
2001, 23(4):354-358.
Abstract:On the basis of the theory for dissipative structure, the main characteristics of Rundle model earthquake are studied in detail.It is found that the double-stable states and the cusp catastrophe are shown in the process of fault dislocation for Rundle model.There are the hysteresis loop of fault dislocation, as the external stress changes between the critical values pc and -pc, and catastrophes occurred at the critical values pc and -pc.The former corresponds to the accumulation of strain energy of the system, and the latter (i.e., strong earthquakes)is the main mechanism for energy dissipation of the system.
2001, 23(4):359-364.
Abstract:Methods determining seismic parameters and mechanical parameters of stratum using data of borehole strain tide and strain seismic wave when elastic parameters of coupling medium in borehole can not be directly determined are introduced.That the substitution of equilibrium equation for wave equation will not only enable the use of borehole strain seismic wave to monitor earthquake, but also greatly simplify the determination methods as compared with direct use of wave equation.
SU Xu , MA Wen-jing , ZHANG Xiao-qing
2001, 23(4):365-369.
Abstract:Regional seismicity characters before and after the Main MS 7.5 earthquake on Nov.8, 1997 and its far-field precursors are analyzed and studied.The results show that before the earthquake, a gap of MS ≥ 5.0 earthquakes has been formed in the south of the epicenter and frequency of ML ≥ 4.0 earthquake along Zangbei seismic zone decreased;Ground stress of Delingha station which is to the east of the epicenter and 940 km distant from it and groundwater temperature of Geermu station which is about 600 km distant from the epicenter have shows of short and impending anomalies.The background of the earthquake and stress field adjustment after the event are approached.
2001, 23(4):369-369.
Abstract:在太阳活动峰年,中国大陆内部和蒙古国内的近东西向断层易于发生8级和8级以上大震,7.5级以上大震也有类似情况,而7级左右地震则此情况不明显。
2001, 23(4):370-376,394.
Abstract:The status and effect of the earthquake prediction in one-year-scale on the emphatic danger zone in Gansu province from 1976 have been analysed.The concerned questions have been discussed.It can be concluded:(1)The corresponding percentage of 19.4 percent indicates the real states of the earthquake prediction in one-year-scale in Gansu.(2)The key to improve the level of the earthquake prediction is that the states of regional seismic activity and precursors variety should be researched and understood further.
ZHANG Chao-jun , LI Zhan-wei , WANG Cui-ping , WANG Bin , ZHAO Meng-sheng , WANG Shu-ming , WANG Yan-wei , LI Tai-lai
2001, 23(4):377-381.
Abstract:Based on the analysis on seismicity and variations of some seismometry indices in Wulateqianqi region, Inner Mongolia from 1998 to July, 2000, seismicity trend of the region in future is studied.It is believed that there is a little possibility of MS 6.0 earthquake to occur in a future year, but there is a larger one of events with magnitude of about 4 or 5 to occur.The gaps on focus depth sections along longitude or latitude may be risk regions of coming strong earthquakes.
2001, 23(4):382-388.
Abstract:Activity characteristics of strong earthquakes in Keping block, Xinjiang since 1969 are analy zed.It is found that the strong earthquakes in the block periodically and circularity occur and the periods are corresponding with active periods of strong earthquakes of Xinjiang region.The seismicities of Xikeer and Wushi small region in the Keping block have a certain significance to prediction of MS ≥ 6 earthquakes in the block.After a MS ≥ 6 earthquakes, activities of MS ≥ 4.5 earthquakes in the block indicated places of coming strong earthquakes in a certain extent.
GAO Guo-ying , WANG Hai-tao , WEN He-ping , WEI Bin
2001, 23(4):389-394.
Abstract:The synthetic focal mechanism solutions of small earthquakes recorded by Wuqia, Kashi and Bachu stations in Xinjiang are used to study background of stress field before mid-strong earthquakes in northeastern Pamir.The results show that the P axis directions of the solutions from the three stations have a dominant distribution respectively, which are indentical with the regional stress field.The directions show a better conformability before four MS ≥ 6.0 earthquakes.Especially, before the Jiashi strong swarm, the direction of the P axes are concentrately distributed from 60°to 70°which are indentical with P axis direction of focal mechanism solution of the swarm.
2001, 23(4):395-403.
Abstract:The formed ages and uplift rates of river terraces of Qilianshan region are determined with the chronologe methed of tectonic-climate circle.The determined ages of the terraces are tested and compared with the results determined by using other methods.The studies indicate the method is practical to determine formed ages of terraces, but the results for low terraces need correcting with field measure data.Tectonic uplift is intermittent and go through four powerful stages since Quaternary period in Qilianshan region.
ZHUANG Kun-yuan , HUANG Bing-shu , WANG Wei , ZHANG Cun
2001, 23(4):404-409,411.
Abstract:According to the requirement of "Instruction for Earthquake Situation Analysis at Site" (revised by Seismological Bureau of China), a system PTDSS (Post-Earthquake Tendency Decision Support System)was built which combined with data processing, earthquake locating, expert system and database as one system.In this system, FAM (Fussy Associative Memory)model is used to make this system having function of self-learning, the main characteristic of second generation expert system.In the knowledge base not only many experts' experiences are collected;but also many valuable new knowledge learnt by system itself is included which is meaningful for tendency decision making up and up to now it is still not summarized by prediction expert.The results of examination for earthquake cases show the system possesses good prediction ability.
2001, 23(4):410-411.
Abstract:据2001年8月23日《长春晚报》报道,最近上海天文台预测,厄尔尼诺事件将在今年年末发生。
Sopyright:China Earthquake Engineering Journal