Cette étude vise à améliorer la connaissance de la structure du bassin de Tadla en se basant sur ... more Cette étude vise à améliorer la connaissance de la structure du bassin de Tadla en se basant sur l'analyse et l'interprétation des données gravimétriques. Une carte de l'anomalie résiduelle a d'abord été calculée à partir de la carte de l'anomalie de Bouguer, qui est fortement affectée par un gradient régional. La carte calculée fournit des informations sur la variation de la densité du sous-sol, mais elle n'apporte pas suffisamment d'éléments, d'où la l'intérêt de recourir à des filtrages dans l'objectif de mettre en évidence les structures affectant le bassin. Nous avons choisi les techniques du gradient horizontal et du prolongement vers le haut, qui permettent de déterminer de nouvelles structures et de fournir des informations sur leurs pendages. La carte structurale de la zone d'étude élaborée constitue un document susceptible de rationaliser les futurs travaux d'exploration des eaux souterraines dans le bassin de Tadla. Pour citer cet article : A. Najine et al., C. R. Geoscience 338 (2006).This study is based on the analysis and the interpretation of the gravity data of the Tadla basin. Its purpose is to increase the knowledge of this basin structure. A residual anomaly map was first calculated from the Bouguer anomaly data witch are strongly affected by a regional gradient. The computed map provides information on the ground density variation but it does not bring enough of new elements. Data filtering allows us to emphasize the structures affecting the basin. We chose the horizontal gradient coupled to the upward continuation techniques that permit to highlight news structures and to give information on their dip. The elaborated structural map of the study area constitutes a useful document for rationalizing the future groundwater exploration in the Tadla basin. To cite this article: A. Najine et al., C. R. Geoscience 338 (2006).
This study is based on a site survey carried out in the capital city of Morocco, Rabat. For this ... more This study is based on a site survey carried out in the capital city of Morocco, Rabat. For this aim, we used a technique based on the recording and processing of seismic ambient noise to characterize local geological conditions in terms of the dynamic response of soil during earthquakes. This technique consists of an assessment of the spectral ratio of the horizontal to vertical components of microtremors recorded at the surface during a few minutes, and allows determination of the fundamental period and the maximum amplification factor at the site of measurement. We applied this technique in the city of Rabat to obtain distribution maps of dominant periods and amplification factors assessed in more than 250 sites. In order to discuss the results of this study, we used the information available in this zone about the lithology and topography to correlate the obtained values of dominant periods and amplification factors with the ground conditions. Finally, we established a microzoning map of the city of Rabat based on the contours of dominant periods. The microzoning map established in this study can be used by engineers and decision makers for urban and land use planning and also as a guide in reduction of the seismic vulnerability of buildings.
Cette étude vise à améliorer la connaissance de la structure du bassin de Tadla en se basant sur ... more Cette étude vise à améliorer la connaissance de la structure du bassin de Tadla en se basant sur l'analyse et l'interprétation des données gravimétriques. Une carte de l'anomalie résiduelle a d'abord été calculée à partir de la carte de l'anomalie de Bouguer, qui est fortement affectée par un gradient régional. La carte calculée fournit des informations sur la variation de la densité du sous-sol, mais elle n'apporte pas suffisamment d'éléments, d'où la l'intérêt de recourir à des filtrages dans l'objectif de mettre en évidence les structures affectant le bassin. Nous avons choisi les techniques du gradient horizontal et du prolongement vers le haut, qui permettent de déterminer de nouvelles structures et de fournir des informations sur leurs pendages. La carte structurale de la zone d'étude élaborée constitue un document susceptible de rationaliser les futurs travaux d'exploration des eaux souterraines dans le bassin de Tadla. Pour citer cet article : A. Najine et al., C. R. Geoscience 338 (2006).This study is based on the analysis and the interpretation of the gravity data of the Tadla basin. Its purpose is to increase the knowledge of this basin structure. A residual anomaly map was first calculated from the Bouguer anomaly data witch are strongly affected by a regional gradient. The computed map provides information on the ground density variation but it does not bring enough of new elements. Data filtering allows us to emphasize the structures affecting the basin. We chose the horizontal gradient coupled to the upward continuation techniques that permit to highlight news structures and to give information on their dip. The elaborated structural map of the study area constitutes a useful document for rationalizing the future groundwater exploration in the Tadla basin. To cite this article: A. Najine et al., C. R. Geoscience 338 (2006).
This study is based on a site survey carried out in the capital city of Morocco, Rabat. For this ... more This study is based on a site survey carried out in the capital city of Morocco, Rabat. For this aim, we used a technique based on the recording and processing of seismic ambient noise to characterize local geological conditions in terms of the dynamic response of soil during earthquakes. This technique consists of an assessment of the spectral ratio of the horizontal to vertical components of microtremors recorded at the surface during a few minutes, and allows determination of the fundamental period and the maximum amplification factor at the site of measurement. We applied this technique in the city of Rabat to obtain distribution maps of dominant periods and amplification factors assessed in more than 250 sites. In order to discuss the results of this study, we used the information available in this zone about the lithology and topography to correlate the obtained values of dominant periods and amplification factors with the ground conditions. Finally, we established a microzoning map of the city of Rabat based on the contours of dominant periods. The microzoning map established in this study can be used by engineers and decision makers for urban and land use planning and also as a guide in reduction of the seismic vulnerability of buildings.
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