The Alhama de Murcia Fault is one of the main active structures of the Eastern Betic Shear Zone (SE Spain), characterized by the presence, along its trace, of Neogene basins developed under early to late Miocene extensional tectonics. A dominant NNW‐SSE shortening direction is active from late Miocene driven by the present‐day plate convergence. We present the structural analysis of the northeastern section of this fault, where reliable estimations of slip rates were unknown due to the lack of geomorphological evidence of recent activity. The recent tectonic evolution and reactivation of the northeastern section are closely related to the Fortuna basin development and tectonic inversion. We approach the structural analysis through the interpretation of seismic reflection profiles, well data, fieldwork, and 3D geological modeling. We estimated a maximum long‐term slip rate of (0.32 +0.18/−0.13) mm/yr in the Librilla sector (last 4.8–7.6 Ma), based on cross‐section restorations and assuming current motion trends from GPS data. According to the results from the cross sections restored along the section and a vertical displacement analysis based on a 3D model, the slip rate distribution shows a decrease of activity toward the northeastern tip of the studied fault section. This supports a transference of deformation between the Alhama de Murcia Fault and the Carrascoy Fault, which seems to absorb part of the shortening during the Plio‐Quaternary, explaining the lower relief created by the activity of the northeastern section. The slip rates obtained have important implications in seismic hazard assessments and in the distribution of deformation along the region.

Earthquake hazard forecasting often has to deal with the scarcity of seismicity data, the complexity of fault segmentation, the uncertainties derived from the characterization of seismogenic sources, the dynamics of earthquake rupture and the recurrence model used. Instrumental earthquake recordings are available only since about 1900 and they are not reliable until several decades later. There are a few regions with representative historical data of large earthquakes for more than 2000 years in Italy (Boschi, 2000), Japan (Ishibashi, 2004), and China (Liu et al., 2011) that allow acquisition of reliable major earthquake magnitudes and recurrence statistics. In regions with low to moderate seismicity, such as some zones of the western Mediterranean or intracontinental areas, earthquake hazard estimation is especially challenging (see e.g., Estay et al., 2016;Gamage & Venkatesan, 2019;Perea & Atakan, 2007). Most of the large, and consequently damaging earthquakes, have recurrence times on the order of hundreds or thousands of years. Since historical catalogs are often scarce and imprecise, the paleoseismic record provides valuable data about rare but devastating major events and long-term recurrence times, but these data usually have large uncertainties (McCalpin, 2009). Often, the slow fault systems, besides generating low seismicity in terms of frequency, show little geomorphological expression. This makes it difficult to define the segmentation of fault traces and the parameters relating to their 3D geometry and their kinematics. Fault system geometry also plays an important role in the stress interactions that control the earthquake ruptures and therefore magnitude and recurrence statistics (e.g.

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Abstract. Strike-slip fault ruptures have a limited capacity to generate vertical deformation, and for this reason they are usually dismissed as potential destructive tsunami sources. At the western tip of the western Mediterranean, in the Alboran Sea, tectonics is characterized by the presence of large transcurrent fault systems and minor reverse and normal faults in a zone of diffuse deformation. The strike-slip Carboneras fault is one of the largest sources in the Alboran Sea and therefore with the greatest seismogenic capacity. It is also one of the active structures with higher slip rates in the eastern Betic fault zone and has been proposed as the source of the damaging 1522 (M 6.5; Int. VIII–IX) Almeria earthquake. The dimensions and location of the Carboneras fault imply a high seismic and tsunami threat. In this paper we present tsunami simulations from seismic sources generated with physics-based earthquake simulators. We have generated a 1 Myr synthetic seismic catalogue consistent on 773 893 events, with magnitudes ranging between Mw 3.3 and 7.6. From these events we have selected those sources producing a potential energy capable of generating a noticeable tsunami, those sources being earthquakes with magnitudes ranging from 6.71 to 7.62. The Carboneras fault has the capacity to generate locally damaging tsunamis; however, on a regional scale its tsunami threat is limited. The frequency–magnitude distribution of the generated seismic catalogue reflects the variability of magnitudes associated with the rupture of the entire fault, departing the upper limit from the classical Gutenberg–Richter potential relation. The inter-event time for the maximum earthquake magnitudes is usually between 2000 and 6000 years. The use of physics-based earthquake simulations for tsunamigenic sources allows an in-depth characterization of the scenarios, allowing a qualitative leap in their parametrization.