GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 1.1 123 INSIGHT ON SEISMIC HAZARD OF THE IBERO-MAGHREBIAN REGION FROM SEISMIC AND GEODETIC MOMENT-RATES COMPARISON F. Sparacino 1 , M. Palano 1 , J.A. Peláez 2 1 Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo - Sezione di Catania, Catania, Italy 2 Department of Physics, University of Jaén, Jaén, Spain Introduction. Seismic and geodetic moment-rates comparison can reveal regions with unexpected potential seismic hazard. Their ratio, expressed as a percentage, is called Seismic Coupling Coefficient (SCC) and allows to differentiate crustal deformation modality (seismic versus aseismic), as well as to highlight regions showing gaps in seismic cycle. We performed such a comparison for Southeastern Iberia - Maghreb region which (Fig. 1), located at the western Mediterranean border along the Eurasian-Nubian plate convergence, has been marked by the occurrence of large earthquakes in the last millennium. To this aim, on the basis of available geological, tectonic and seismological data, we divided the study area in twenty-five seismogenic source zones. Data and methodology. For each seismogenic source zone, the seismic moment-rate was computed according to the Hyndman and Weichert (1983) formulation, obtained by integrating the cumulative truncated Gutenberg-Richter distribution up to a maximummagnitude value, i.e., the magnitude of the largest earthquake that could occur within a specified region. These values and associated uncertainties have been estimated by adopting different approaches. Regarding the Spanish seismogenic source zones, maximum values have been primarily estimated on the dimensions of known active faults and considerations of the maximum dimension of other mapped faults and structures recognized on field by adopting the empirical laws reported in Wells and Coppersmith (1994). For the zones characterized by a lack tectonic data, maximum values have been estimated directly from the seismic catalog by adopting a cumulative exponential-truncated Gutenberg-Richter recurrence relationship. Regarding the seismic source zones located along the African margin, maximum values have been estimated from the seismic Fig. 1 - Simplified tectonic map of the Southeastern Iberia - Maghreb region. Seismogenic sources are also reported.