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11.
Djillali Benouar 《Natural Hazards》1996,13(2):119-131
This paper presents the evaluation of seismic hazard at the site of Algiers (capital of Algeria). In order to implement earthquake-resistant design codes, it is usually necessary to know the maximum dynamic load which a particular structure might experience during its economic life, or alternatively, the most probable return period of a specified design load. The evaluation of the seismic hazard at the site, based on peak ground motion acceleration and using Cornell's method and Benouar's earthquake Maghreb catalogue, in terms of return period, probability of exceedance of PGA, design ground motion and a response spectrum, is carried out for the City of Algiers and its surroundings. The response spectrum for Algiers presented in this paper is the first one realized in Algeria using revised Algerian data. 相似文献
12.
D. Benouar 《地震工程与结构动力学》1994,23(7):717-727
This paper presents the results of an investigation of the magnitude–intensity and intensity–attenuation relationships for earthquakes in the Atlas block and Algeria using macroseismic data. This work is based on a selected sample of isoseismal maps from 32 events which were recently revised. Surface-wave magnitudes, Ms, are recalculated using the Prague formula and range from 4·2 to 7·45. Because the Atlas mountains block is in a collision zone, earthquakes occur in general within a layer 15 km deep. Expressions of general form for the magnitude–intensity and intensity–attenuation correlations are adopted and are, respectively, and where R2 = d2 + h2, d the source distance in km, h the focal depth in km, Ms the revised surface-wave magnitude, Msc the predicted surface-wave magnitude, Ii the intensity at isoseismal i, I the predicted intensity, σ the standard deviation and P is zero for 50-percentile values and one for 84-percentile, and the coefficients A's and B's are determined by regression analysis. The results of this study show that the intensity–attenuation models are adequate to predict quite well the die-out of intensity with distance in the Atlas zone and coastal Algeria; it is also found that magnitude can be predicted accurately by calibrating isoseismal radii against revised instrumental surface-wave magnitude. Such magnitude–intensity relationships may be used to evaluate the magnitude of historical earthquakes in the region under survey, with no instrumental data, for which isoseismal radii and intensities are available. 相似文献
13.
As large destructive seismic events are not frequent in Algeria, anexhaustive knowledge of the historical seismicity is required to have arealistic view of seismic hazard in this part of the world. This research workpresents a critical reappraisal of seismicity in the north-eastern Algeria forseismotectonic and seismic hazard purposes. This part of work focuses onthe seismicity of pre-1900 period for the area under consideration[33°N-38°N, 4°E-9.5°E]. By going back tothe available documentary sources and evaluating and analysing the eventsin geographical, cultural and historical context, it has been possible toidentify 111 events, from 1850–1899, which are not reported in therecent Algerian catalogue. Several spurious events, reported in standardlistings, have been deleted and nine unknown events have been discovered.It is quite clear that macroseismic information derived from press reportsand published documents in Algeria, under certain conditions, is veryincomplete, even for destructive earthquakes, located in the countrysideaway from communication centres. One of the reasons for this iscensorship, noticeable during the colonisation period. Critical analysis ofnewly collected information has allowed the determination and/or theimprovement of the macroseismic parameters of each event, such aslocation, maximum epicentral intensity and magnitude to produce anearthquake catalogue as homogeneous and complete as the available data,for the zone under study. The criteria used in this research are explainedand eight historical earthquakes have been the subject of retrospectivemacroseismic field construction.The investigation of historical earthquakes is one of the most important taskin studying seismotectonic for seismic hazard evaluation purposes. 相似文献
14.
The Bou Medfaa earthquake of 7 November 1959 occurred at 2 h 32 min 7 s (GMT); it is one of the most destructive seismic events that central Algeria experienced this century. The main shock, which lasted 8 s in Bou Medfaa, caused only two injuries but made at least 500 homeless; it destroyed or heavily damaged more than 80% of the houses, farms and public buildings in Bou Medfaa and its immediate surroundings. Poor-quality constructions were the main cause of the damage. The total cost of damage was estimated at 300 million French francs. The earthquake was preceded by two slight foreshocks and followed by a series of lower intensity aftershocks. It was associated with slight surface ground fissures in Bou Medfaa. Compilation and detailed study of the contemporary source documents relative to this earthquake have led to the reconstruction of its macroseismic field and thus to the re-assessment of the strength of the ground shaking. Intensities were re-evaluated anew in many sites. Maximum intensity has been re-estimated at I0 = VIII (MSK), assigned to Bou Medfaa, Hammam Righa and their close vicinities, an area about 8 km radius. The shock was felt as far as Dellys 150 km away with intensity III (MSK). From the intensity data, the macroseismic epicentre was located slightly north of Bou Medfaa at 36·41°N, 2·48°E, and an isoseismal map of the main shock has been constructed. The surface-wave magnitude has been calculated, without station corrections, at 4·90 (±0·40). The instrumental epicentre has been relocated, using the present location procedure of the ISC, at 36·38°N, 2·55°E. The analysis of destructive earthquakes provides a fundamental means for the reduction of future seismic catastrophes by suggesting new ways of improving local construction procedures, building materials, strengthening and properly repairing existing structures and implantation of new urban and rural settlements. 相似文献
15.
Seismicity and Tectonic Structures in the Site of Algiers and its Surroundings: A Step Towards Microzonation 总被引：5，自引：0，他引：5
A. Harbi S. Maouche A. Ayadi D. Benouar G. F. Panza H. Benhallou 《Pure and Applied Geophysics》2004,161(5-6):949-967
— We intend to reappraise the seismogenic potential of the geologic structures in the site of Algiers and its surroundings. A compilation of a working earthquake catalogue is first made using all events reported in all previous documentation available. However for the sake of homogeneity and a certain degree of reliability of the data, only revised seismic events with epicenter coordinates, magnitude and/or intensity are included. A tectonic setting of the zone under investigation and available fault plane solutions are presented. The results obtained in previous seismological studies of the most recent earthquakes of the area are also discussed. The findings highlight the great interest to be taken in the detailed and timely assessment of the seismic hazard of Algiers and its surroundings which is made possible by the realistic modelling of the scenario seismic input. 相似文献
16.
A. Mendas A. Delali M. Khalfallah L. Likou M. A. Gacemi H. Boukrentach A. Djilali R. Mahmoudi 《Arabian Journal of Geosciences》2014,7(2):435-445
The weighted sum already incorporated into a geographical information system (GIS) makes it possible to identify the best lands useful for sustainable agriculture. However, it does not allow for the inclusion of the decision makers’ preferences so that a choice can be made when there are conflicts between decision makers. Because of their spatial aggregation functions, multicriteria decision analysis methods can facilitate decision making in situations where several solutions are available, various criteria have to be taken into account, and decision makers disagree about one point or another. Combinations between ArcGIS and multicriteria analysis methods in this case Elimination Et Choix Traduisant la Realité (ELECTRE TRI) and a version of the weighted sum method simple additive weighting, applicable to the vector data model, have been established. The parameters and the classification system of Food and Agriculture Organization are used in this work. This approach has been tested on the area of Mleta in Algeria. Land suitability maps for durum wheat have been produced. Through the comparison between results obtained by these two methods and those available in a classical method, based on manual overlay procedures, it appears that optimistic procedure of the ELECTRE TRI method is better suited to the problem of land suitability for agriculture. 相似文献