河南内乡-镇平ML4.7级地震及其震前 地震活动特征   总被引：2，自引：1，他引：2  

谢智  王文旭  刘尧兴  胡凤英  许孝法 《华南地震》2001,21(1):26-31

2000年4月29日河南内乡－镇平ML4．7级地震是一次显著地震事件，地震序列属孤立型，根据震区地震地质背景，等震线分布以及震源机制解的综合分析表明，发震断层为北西向的朱阳关－桐柏断裂，对1992年至今该区2．0级以上地震空间分布的研究认为，震前的地震空间分在由无序到有序的演化过程，即存在一个地震正常活动，地震空间，地震条带，震前震中区平静至发震的发展过程。  相似文献   

Seismicity, seismotectonics and crustal structure of the southern Kenya Rift—new data from the Lake Magadi area     

M. Ibs-von Seht  S. Blumenstein  R. Wagner  D. Hollnack  J. Wohlenberg 《Geophysical Journal International》2001,146(2):439-453

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Probabilistic Seismic Hazard Assessment Along the Southeastern Coast of Vietnam     

Hong Phuong  Nguyen 《Natural Hazards》2001,24(1):53-74

On the basis of the analysis of geological, tectonic characteristics and earthquake manifestation features, a causative relation between geodynamic regime and seismicity has been established for the southeastern coastal zone and continental shelf of Vietnam. The probabilistic methods have been used to evaluate ground shaking effects at Nha Trang city aswell as for the entire study area. Short, intermediate and long term predictions of ground shaking (in the form of peak ground accelerationmaps) show high risks in the coastal zone of central Vietnam and in the southeastern continental shelf of the country.  相似文献   

Induced seismicity at wujiangdu reservoir,China: a case induced in the karst area   总被引：6，自引：0，他引：6  

Hu Yuliang  Liu Zuyuan  Yang Oingyuan  Chen Xiancheng  Hu Ping  Ma Wentao  Lei Jun 《Pure and Applied Geophysics》1996,147(2):409-418

To date 19 cases of reservoir-induced seismicity have been acknowledged in China and 15 of them are associated with karst. The Wujiangdu case is a typical one induced in the karst area. The dam with a height of 165 m is the highest built in a karst area in China. Seismic activity has been successively induced in five reservoir segments seven months after the impoundment in 1979. A temporary seismic network consisting of 8 stations was set up in one of the segments some 40 km upstream from the dam. The results indicate that epicenters were distributed along the immediate banks, composed of karstified carbonate, and focal depths were only several hundred meters. Most of the focal mechanisms were of thrust and normal faulting. It is suggested that karst may be an important factor in inducing seismicity. It can provide an hydraulic connection to change the saturation and pressure and also weak planes for dislocation to induce seismicity.  相似文献   

Space-time interaction amongst clusters of mining induced seismicity   总被引：1，自引：0，他引：1  

A. Kijko  C. W. Funk 《Pure and Applied Geophysics》1996,147(2):277-288

Elementary cluster analysis of induced seismicity in a South African gold mine has shown that there is a clear interaction amongst the clusters; and that the level of the interaction is a function of the distance. The clusering algorithm used is an adaptation of the single-link cluster analysis which considers both three-dimensional space and time. A high level of interaction between the clusters is demonstrated from the cross-correlation analysis of seismic activity rates and radiated energy. A distinct decrease in the value of correlation coefficients was detectable as distance increased. This was somewhat surprising, considering the simplicity of the technique used. Since no attempt is made to study the physical mechanisms of interaction, these results are very preliminary, but interesting from an observational point of view.  相似文献   

Seismotectonic models and CN algorithm: The case of Italy     

Giovanni Costa  Ivanka Orozova-Stanishkova  Giuliano Francesco Panza  Irina M. Rotwain 《Pure and Applied Geophysics》1996,147(1):119-130

The CN algorithm is utilized here both for the intermediate term earthquake prediction and to validate the seismotectonic model of the Italian territory. Using the results of the analysis, made through the CN algorithm and taking into account the seismotectonic model, three main areas, one for Northern Italy, one for Central Italy and one for Southern Italy, are defined. Two transition areas between the three main areas are delineated. The earthquakes which occurred in these two areas contribute to the precursor phenomena identified by the CN algorithm in each main area.  相似文献   

A determination of source properties of large intraplate earthquakes in Alaska     

Hilary J. Fletcher  Douglas H. Christensen 《Pure and Applied Geophysics》1996,146(1):21-41

Historically, large and potentially hazardous earthquakes have occurred within the interior of Alaska. However, most have not been adequately studied using modern methods of waveform modeling. The 22 July 1937, 16 October 1947, and 7 April 1958 earthquakes are three of the largest events known to have occurred within central Alaska (M _s =7.3,M _s =7.2 andM _s =7.3, respectively). We analyzed teleseismic body waves to gain information about the focal parameters of these events. In order to deconvolve the source time functions from teleseismic records, we first attempted to improve upon the published focal mechanisms for each event. Synthetic seismograms were computed for different source parameters, using the reflectivity method. A search was completed which compared the hand-digitized data with a suite of synthetic traces covering the complete parameter space of strike, dip, and slip direction. In this way, the focal mechanism showing the maximum correlation between the observed and calculated traces was found. Source time functions, i.e., the moment release as a function of time, were then deconvolved from teleseismic records for the three historical earthquakes, using the focal mechanisms which best fit the data. From these deconvolutions, we also recovered the depth of the events and their seismic moments. The earthquakes were all found to have a shallow foci, with depths of less than 10 km.The 1937 earthquake occurred within a northeast-southwest band of seismicity termed the Salcha seismic zone (SSZ). We confirm the previously published focal mechanism, indicating strike-slip faulting, with one focal plane parallel to the SSZ which was interpreted as the fault plane. Assuming a unilateral fault model and a reasonable rupture velocity of between 2 and 3 km/s, the 21 second rupture duration for this event indicates that all of the 65 km long SSZ may have ruptured during this event. The 1947 event, located to the south of the northwest-southeast trending Fairbanks seismic zone, was found to have a duration of about 11 seconds, thus indicating a rupture length of up to 30 km. The rupture duration of the 1958 earthquake, which occurred near the town of Huslia, approximately 400 km ENE of Fairbanks, was found to be about 9 seconds. This gives a rupture length consistent with the observed damage, an area of 16 km by 64 km.  相似文献   

信息增益在地震趋势估计中的应用   总被引：2，自引：0，他引：2  

沈萍  冯国政 《中国地震》1996,12(4):378-382

从熵中信息增益的定义出发，将地震中的能量和频度作为一个整体考虑，研究了全球１９００－１９９２斫Ｍ≥６．０地震的信息增益。结果表明，强震前有信息增益减小的特点。信息增益方法的引入，为利用中小地震进入地震跟踪预报提供了一个新途径。  相似文献   

Tectonic analysis of mine tremor mechanisms from the Upper Silesian Coal Basin     

Grzegorz Sagan  Lesław Teper  Waclaw M. Zuberek 《Pure and Applied Geophysics》1996,147(2):217-238

Fault network of the Upper Silesian Coal Basin (USCB) is built of sets of strike-slip, oblique-slip and dip-slip faults. It is a typical product of force couple which acts evenly with the parallel of latitude, causing horizontal and anti-clockwise movement of rock-mass. Earlier research of focal mechanisms of mine tremors, using a standard fault plane solution, has shown that some events are related to tectonic directions in main structural units of the USCB. An attempt was undertaken to analyze the records of mine tremors from the period 1992–1994 in the selected coal fields. The digital records of about 200 mine tremors with energy larger than 1×10⁴ J (M _L >1.23) were analyzed with SMT software for seismic moment tensor inversion. The decomposition of seismic moment tensor of mine tremors was segmented into isotropic (I) part, compensated linear vector dipole (CLVD) part and double-couple (DC) part. The DC part is prevalent (up to 70%) in the majority of quakes from the central region of the USCB. A group of mine tremors with large I element (up to 50%) can also be observed. The spatial orientation of the fault and auxiliary planes were obtained from the computations for the seismic moment DC part. Study of the DC part of the seismic moment tensor made it possible for us to separate the group of events which might be acknowledged to have their origin in unstable energy release on surfaces of faults forming a regional structural pattern. The possible influence of the Cainozoic tectonic history of the USCB on the recent shape of stress field is discussed.  相似文献   

1996年1—3月的全球地震动态     

吴佳翼 《国际地震动态》1996,(8):18-20

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