A MAIN EARTHQUAKE CATALOG FOR SEISMIC HAZARD STUDIES IN NORTHERN MOROCCO

In this study we present an earthquake catalog, including its main properties, in terms of moment magnitude and spanning from years 1045 to 2005, aimed to perform seismic hazard studies in Northern Morocco. It embraces a region geographically limited within 27°-37°N and 15°W-1°E. In order to obtain a main earthquake catalog for this region as complete and homogeneous as possible, we have conducted the following steps. Firstly, data from different local (Spanish IGN, Moroccan CNRM, Algerian CRAAG, …) and international (ISC, EMSC, Harvard CMT, …) seismological agencies have been collected, as well as from numerous published papers about the seismicity of the region, including both historic and instrumental events. Then, empirical relationships among reported magnitudes (mb, mbLg, MS, ML and MD) or macroseismic intensity and moment magnitude (MW), some of them developed specifically for the region, were used to compile a uniform catalog. For those earthquakes with marine epicenter and reported Imax values, epicentral intensity has been computed from attenuation relationships. Finally, all non-Poissonian earthquakes, including foreshocks, aftershocks and swarms, as well as events with magnitude smaller than MW 3.0, have been removed. The obtained final catalog, although not as complete and uniform as it could be desirable for this type of studies, certainly improves those compiled until now in the region of interest. The catalog can be considered complete approximately since 1910 for magnitudes above MW 4.0, and approximately since 1700 for magnitudes above MW 6.0.