Materials for the investigation of historical seismicity in Algeriafrom the records of past earthquakes

This paper presents some materials relating to the investigation of historical seismicity in Algeria. The historical seismicity in Algeria is imperfectly known: its coverage is discontinuous and its record is grossly deficient. The seismicity of the twentieth century is relatively well documented; however, the further back in time, the harder it becomes to collect data. Even so, important research work in studying the seismicity in Algeria has been made in the past by several studies, notably those by Alexis Perrey, M. Chesneau, F. de Montessus de Ballore, N.N. Ambraseys and J. Vogt. This paper discusses the problems of historical earthquake investigation in Algeria and presents a selection of notable historical earthquakes in the country

Materials for the investigation of The Seismicity Of Algeria And Adjacent Regions during the twentieth century

Dr. Benouar presents a full and integrated study of the recent seismicity of Algeria and adjacent regions during the twentieth century. He has amassed an impressive amount of macroseismic information pertaining to individual earthquakes, which he combines with instrumental information to reassess the origin parameters of each event. In any compilation of earthquakes it is the additional information beyond the bare accumulation of figures and facts that adds interest and social understanding to the scientific appreciation of the earthquakes themselves. For this it is necessary to know the local conditions, and Dr. Benouar brings out for us very vivid1y the differences between reporting procedures at different times this century, and the ensuing difficulties. It would be most difficult for an outsider to gather the information he presents, and he makes good use of his knowledge of his native land, as well as his professional training as an engineer. We thus learn of the reluctance of the colonial powers to report on damage or casualties outside those inflicted on the expatriate community, and the general difficulties of finding information about earthquakes that occurred during the wars of independence, at a time when effects of even major earthquakes were sometimes minor compared to those of the war itself. He also does not spare us details of political difficulties that arose during periods of reconstruction following recent earthquakes. This work is not restricted, however, to description. He examines the underlying tectonics of the area and deduces estimates of hazard and risk in various parts of the country. He then proceeds to examine the engineering consequences and discuss future needs for building codes and civil protection. Dr. Benouar has produced a work which could well form a model for those wishing to undertake comprelzensive studies of seismicity of other areas, and the measures needed to reduce the effects of catastrophic earthquakes

Materials for the investigation of historical seismicity in Algeriafrom the records of past earthquakes

This paper presents some materials relating to the investigation of historical seismicity in Algeria. The historical seismicity in Algeria is imperfectly known: its coverage is discontinuous and its record is grossly deficient. The seismicity of the twentieth century is relatively well documented; however, the further back in time, the harder it becomes to collect data. Even so, important research work in studying the seismicity in Algeria has been made in the past by several studies, notably those by Alexis Perrey, M. Chesneau, F. de Montessus de Ballore, N.N. Ambraseys and J. Vogt. This paper discusses the problems of historical earthquake investigation in Algeria and presents a selection of notable historical earthquakes in the country

Materials for the investigation of The Seismicity Of Algeria And Adjacent Regions during the twentieth century

Dr. Benouar presents a full and integrated study of the recent seismicity of Algeria and adjacent regions during the twentieth century. He has amassed an impressive amount of macroseismic information pertaining to individual earthquakes, which he combines with instrumental information to reassess the origin parameters of each event. In any compilation of earthquakes it is the additional information beyond the bare accumulation of figures and facts that adds interest and social understanding to the scientific appreciation of the earthquakes themselves. For this it is necessary to know the local conditions, and Dr. Benouar brings out for us very vivid1y the differences between reporting procedures at different times this century, and the ensuing difficulties. It would be most difficult for an outsider to gather the information he presents, and he makes good use of his knowledge of his native land, as well as his professional training as an engineer. We thus learn of the reluctance of the colonial powers to report on damage or casualties outside those inflicted on the expatriate community, and the general difficulties of finding information about earthquakes that occurred during the wars of independence, at a time when effects of even major earthquakes were sometimes minor compared to those of the war itself. He also does not spare us details of political difficulties that arose during periods of reconstruction following recent earthquakes. This work is not restricted, however, to description. He examines the underlying tectonics of the area and deduces estimates of hazard and risk in various parts of the country. He then proceeds to examine the engineering consequences and discuss future needs for building codes and civil protection. Dr. Benouar has produced a work which could well form a model for those wishing to undertake comprelzensive studies of seismicity of other areas, and the measures needed to reduce the effects of catastrophic earthquakes

Post-seismic damage evaluation: a probability-based global damage index

International audienc

Seismic Base Shear Force Depending on Building Fundamental Period and Site Conditions: Deterministic Formulation and Probabilistic Analysis

The aim of this paper is to investigate the effect of the building fundamental period of reinforced concrete buildings of (6, 9, and 12-storey), with different floor plans: Symmetric, mono-symmetric, and unsymmetric. These structures are erected at different epicentral distances. Using the Boumerdes, Algeria (2003) earthquake data, we focused primarily on the establishment of the deterministic formulation linking the base shear force to two parameters: The first one is the fundamental period that represents the numerical fingerprint of the structure, and the second one is the epicentral distance used to represent the impact of the earthquake on this force. In a second step, with a view to highlight the effect of uncertainty in these parameters on the analyzed response, these parameters are modeled as random variables with a log-normal distribution. The variability of the coefficients of variation of the chosen uncertain parameters, on the statistics on the seismic base shear force, showed that the effect of uncertainty on fundamental period on this force statistics is low compared to the epicentral distance uncertainty influence

Attenuation relationships for HPGA: sensitivity analysis and applications

International audienc

A procedure for the identification of the seismic vulnerability at territorial scale. application to the Casbah of Algiers

One of the objectives of the PERPETUATE EU-FP7 project was to determine a sound approach to the quantification of the seismic vulnerability of historic centres at territorial scale. The procedure presented herein provides a ten steps guideline from how to select building samples in the area of study, to how to compute the buildings’ seismic performance and finally how to evaluate rehabilitation decisions to reduce the seismic fragility of the studied typologies over an entire district or city. The procedure is illustrated in this paper by way of application to The Casbah of Algiers, a world heritage site composed of building clusters from the Ottoman to the French period. Pre-existing seismic damage, decay due to lack of maintenance and environmental factor and a urban irregular and complex lay-out make this application particularly challenging. A total number of around 150 houses, characterised by the most representative features of the Algerian historic construction, have been selected in collaboration with the Directorate of the Office for Management of Cultural Property of the Ministry of Culture,. The seismic Vulnerability Assessment Method (VAM) underpinning the 10-step procedure is is FaMIVE (Failure Mechanism Identification and Vulnerability Evaluation), a mechanical approach based on limit state analysis and kinematics, which allows computing collapse load factor, deriving capacity curves and determining fragility functions. As the approach identifies also the collapse mechanisms, it provides a base for choosing and evaluating the effects of strengthening interventions, which are rolled out at territorial level to improve the seismic performance of the whole sample. The effectiveness of the present procedure for the identification of the seismic vulnerability at territorial scale is discussed in the conclusions