Abstract:
We estimate the energetic and spatial characteristics of seismicity in the
Algeria–Morocco region using a variety of seismic and statistical parameters, as a first step
in a detailed investigation of regional seismic hazard. We divide the region into five
seismotectonic regions, comprising the most important tectonic domains in the studied
area: the Moroccan Meseta, the Rif, the Tell, the High Plateau, and the Atlas. Characteristic
seismic hazard parameters, including the Gutenberg–Richter b-value, mean seismic
activity rate, and maximum possible earthquake magnitude, were computed using an
extension of the Aki–Utsu procedure for incomplete earthquake catalogs for each domain,
based on recent earthquake catalogs compiled for northern Morocco and northern Algeria.
Gutenberg–Richter b-values for each zone were initially estimated using the approach of
Weichert (Bull Seismol Soc Am 70:1337–1346, 1980): the estimated b-values are
1.04 ± 0.04, 0.93 ± 0.10, 0.72 ± 0.03, 0.87 ± 0.02, and 0.77 ± 0.02 for the Atlas,
Meseta, High Plateau, Rif, and Tell seismogenic zones, respectively. The fractal dimension
D2 was also estimated for each zone. From the ratio D2/b, it appears that the Tell and Rif
zones, with ratios of 2.09 and 2.12, respectively, have the highest potential earthquake
hazard in the region. The Gutenberg–Richter relationship analysis allows us to derive that
in the Tell and Rif, the number of earthquake with magnitude above Mw 4.0, since 1925
normalized to decade and to square cell with 100-km sides is equal to 2.6 and 1.91,
respectively. This study provides the first detailed information about the potential seismicity
of these large domains, including maximum regional magnitudes, characteristics of
spatial clustering, and distribution of seismic energy release.
