Geodetic Deformation versus Seismic Crustal Moment-Rates: Insights from the Ibero-Maghrebian Region

Abstract

Seismic and geodetic moment-rate comparisons can reveal regions with unexpected potential seismic hazards. We performed such a comparison for the Southeastern Iberia—Maghreb region. Located at the western Mediterranean border along the Eurasia–Nubia plate convergence, the region has been subject to a number of large earthquakes (M ≥ 6.5) in the last millennium. To this end, on the basis of available geological, tectonic, and seismological data, we divided the study area into twenty-five seismogenic source zones. Many of these seismogenic source zones, comprising the Western Betics, the Western Rif mountains, and the High, Middle, and Saharan Atlas, are characterized by seismic/geodetic ratio values lower than 23%, evidencing their prevailing aseismic behavior. Intermediate seismic/geodetic ratio values (between 35% and 60%) have been observed for some zones belonging to the Eastern Betics, the central Rif, and the Middle Atlas, indicating how crustal seismicity accounts only for a moderate fraction of the total deformation-rate budget. High seismic/geodetic ratio values (> 95%) have been observed along the Tell Atlas, highlighting a fully seismic deformation.

High‐ and Low‐Angle Normal Fault Activity in a Collisional Orogen: The Northeastern Granada Basin (Betic Cordillera)

“…Stich et al (2006) calculated a horizontal regional compression in the NW-SE direction, parallel to the shortening direction. Sparacino et al (2020) presented evidence supporting both NE-SW extension and NW-SE shortening. Despite the scarce availability of focal mechanisms, they serve to reveal the structure, to compute the stress regime, and to discuss the tectonic model.…”

“…Sparacino et al. (2020) presented an evidence supporting both NE‐SW extension and NW‐SE shortening. Despite the scarce availability of focal mechanisms, they serve to reveal the structure, to compute the stress regime, and to discuss the tectonic model.…”

Geometry and kinematics of the Baza Fault (central Betic Cordillera, South Spain): insights into its seismic potential

“…This difference could be related to the fact that calculations using long term slip-rates may be overestimated. Long-term slip rates incorporate the seismic displacement, but also the potential aseismic displacement related to creeping processes along the BF (Sparacino et al, 2020) and the displacement produced by low-magnitude earthquakes with no surface ruptures. On the contrary, recurrence intervals obtained from the palaeoseismological data may be underestimated.…”

Crustal deformation, active tectonics and seismic potential in the Sicily Channel (Central Mediterranean), along the Nubia–Eurasia plate boundary

“…This comparison allows identifying regions where deformation is entirely released by crustal seismicity from those where the excess of deformation can be released either through large impending earthquakes or aseismic slip across creeping faults. Examples where this comparison has been successfully applied encompass several tectonic regions worldwide, including Iran 1 , 2 , western Canada 3 , western USA 4 , Greece 5 and the western Mediterranean 6 .…”