Seismic site effect estimation in the city of Rabat (Morocco)

Abstract

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.