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1.
The new procedure of earthquake hazard evaluation developed by Kijko and Sellevoll is tested and applied for the border region of Czechoslovakia and Poland. The new method differs from the conventional approach. It incorporates the uncertainty of earthquake magnitudes, and accepts mixed data containing only large historical events and recent, complete catalogues. Seismic hazard has been calculated for nine regions determined in the border area. In the investigated area, data of historical catalogues are uncertain or, in many cases, the epicentral intensities are unknown. Thus, a number of assumptions have to be adopted in data preparation of catalogues since the year 1200. The calculated values of parameters b in the Gutenberg-Richter frequency-intensity relation as well as the return periods, seem to be reasonable and are generally confirmed by the results obtained from catalogues for the last 80–130 years. 相似文献
2.
A general overview of some of the problems involved in earthquake catalogue handling is given as part of the works carried out into the ESC/SC8-TERESA project related with the seismic hazard assessment in two selected test areas: Sannio-Matese in Italy and the northern Rhine region (BGN). Furthermore, the necessary input data to be used in the calculation of seismic hazard has been obtained, including earthquake source zones and their seismic hazard parameters.The importance is pointed out of detailed analysis of seismic catalogues, mainly in relation to the use of aftershock information, the historical records of the region, and the possible temporal and spatial variation of seismicity, which could have an important influence on short-term hazard assessment. 相似文献
3.
M. S. Barbano J. J. Egozcue M. García Fernández A. Kijko J. Lapajne D. Mayer-Rosa V. Schenk Z. Schenková D. Slejko G. Zonno 《Natural Hazards》1989,2(3-4):217-228
The working group on Test Regions for Evaluation of Methods for Seismic Hazard Assessment in Europe (TERESA), consisted of 15 members from 10 different European countries. Methods and experience gathered in these countries have been compared and discussed for two test areas in Europe: the Sannio-Matese region, Southern Italy, with high seismic activity, and the border region between Belgium, The Netherlands, and Federal Republic of Germany, with low activity.This paper summarizes the results for one of the test areas, Sannio-Matese. Most of the participants used statistical procedures to assess earthquake hazard, receiving results in terms of probability of occurrence for intensity as the ground-motion parameter. It was found that careful preparation of input data and parameters is the major influencing factor, therefore most of the efforts of the working group was devoted to this task.The scatter of the obtained results of the group is considerable, mainly because of the uncertainties in the data and the subjectiveness involved in the procedures. For better control of both factors, more objective methods have to be developed. 相似文献
4.
5.
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
6.
In this part of our study the probabilistic seismic hazard analysis (PSHA) for Tulbagh was performed. The applied procedure is parametric and consists essentially of two steps. The first step is applicable to the area in the vicinity of Tulbagh and requires an estimation of the area-specific parameters, which, in this case, is the mean seismic activity rate, , the Gutenberg-Richter parameter, b, and the maximum regional magnitude, mmax. The second step is applicable to the Tulbagh site, and consists of parameters of distribution of amplitude of the selected ground motion parameter. The current application of the procedure provides an assessment of the PSHA in terms of peak ground acceleration (PGA) and spectral acceleration (SA). The procedure permits the combination of both historical and instrumental data. The historical part of the catalogue only contains the strongest events, whereas the complete part can be divided into several subcatalogues, each assumed complete above a specified threshold of magnitude. In the analysis, the uncertainty in the determination of the earthquake was taken into account by incorporation of the concept of `apparent magnitude'. The PSHA technique has been developed specifically for the estimation of seismic hazard at individual sites without the subjective judgement involved in the definition of seismic source zones, when the specific active faults have not been mapped or identified, and where the causes of seismicity are not well understood. The results of the hazard assessment are expressed as probabilities that specified values of PGA will be exceeded during the chosen time intervals, and similarly for the spectral accelerations. A worst case scenario sketches the possibility of a maximum PGA of 0.30g. The results of the hazard assessment can be used as input to a seismic risk assessment. 相似文献
7.
Andrzej Kijko 《Pure and Applied Geophysics》1977,115(4):1011-1021
Summary Seven optimal networks consisting of 4 to 10 stations are compared for a given region, where velocity-depth profiles and the distribution of seismic intensity are known. Assuming that the standard error of arrival time is
t
=0.05 s and the standard errors of the parameters of velocity-depth profiles are equal to 5% of their values, the average standard errors of the origin time
and focus coordinates
are estimated. The application of optimum methods to the planning of seismic networks in the Lublin Coal Basin is presented, and maps of standard errors of origin time
, depth
and epicenter (
xy
) for the case of an optimum network of 6 seismic stations are given. 相似文献
8.
Natural Hazards - This study examines the effect of the procedures used in three different probabilistic seismic hazard analysis (PSHA) methods for estimating the rates of exceedance of ground... 相似文献
9.
Earthquake motion is one of the extreme loads acting on large dams. Dam owners and regulators must therefore ensure that dams
are safely operated and present minimal risk to the public in case of extreme loads such as floods and earthquakes. Owners
of many dams or officials in charge of dam safety programs may consider comparative assessment of the seismic risk associated
with their dams and establish priorities for detailed evaluation. South Africa has in excess of 100 large state-owned dams
and the characteristics of these dams have been used to perform a basic seismic hazard assessment and rank the vulnerability
of these dams from the lowest to highest. One of the most decisive factors that contributes to the risk of a dam is the wall
type; with gravity and earthfill dams being the most vulnerable to earthquake motion. Another aspect that needs further investigation
is the downstream hazard potential which, if known to a better degree of accuracy, can provide more reasonable estimates of
the risk factors. 相似文献
10.
A first-order seismotectonic model was created for South Africa. This was done using four logical steps: geoscientific data
collection, characterisation, assimilation and zonation. Through the definition of subunits of concentrations of earthquake
foci and large neotectonic and structural domains, seismotectonic structures, systems and domains were created. Relatively
larger controls of seismicity exist between the Great Escarpment and the coast. In the south, this region is characterised
by large aeromagnetic anomalies and large EW trending faults. In the west, it is characterised by the NW–SE trending Wegener
stress anomaly, radial-trending dykes and earthquake clusters. In the east, it is characterised by a large neotectonic domain
where several large historical earthquakes occurred. In the centre of South Africa, several clusters of earthquake activity
are found, often related to mining activity. Further north, seismicity is related to both mining activity and neotectonic
deformation. This work contributes to the development of a seismotectonic model for South Africa by (1) bringing together,
digitally, several data sets in a common GIS platform (geology, geophysics, stress, seismicity, neotectonics, topography,
crustal and mantle structure and anisotropy), (2) understanding the significance of data sets for seismotectonic zonation
and limitations thereof and (3) obtaining a reasonable regional model for use in seismic hazard assessments. 相似文献