SEISMIC MICROZONATION AND SITE EFFECTS AT AL HOCEIMA CITY,MOROCCO

Measurements of background noise at Al Hoceima city and its extension zones allowed us to elaborate a seismic microzonation map. The analysis of this map shows existing relationships between the observed dominant periods and the local geological conditions. In particular, a strong correlation between the dominant periods and the topography is apparent; indeed, we find larger dominant periods in areas with higher topography such as in the Ras El Abed sector to the north of the city and in the area of Cala Bonita, south of the city. Furthermore, the field work conducted in the region revealed that the karstic phenomenon is well developed in the Ras El Abed sector, and affects the dominant periods and a hence the site response.