# Stochastic Modeling of the Al Hoseima (Morocco) Aftershock Sequences of 1994, 2004 and 2016
## 2 Geological Setting Overview  
The Rif, along with the Betics, forms the westernmost alpine ranges of the Mediterranean Sea and are linked by the Gibraltar Arc. The Alboran Sea is in the center (Figures 1 and 2). The central-south region of the Alboran Sea and the eastern Rif Cordillera belong to the seismically active area of Al Hiceima. The Internal and External Zones separated by the Flysch Units tectonically constitute the Rif Cordillera. In addition, several late intramontane Neogene-Quaternary sedimentary basins emerged, some of which were linked to the Alboran Sea, forming the largest basin of the orogen [15]. The Internal Zone comprises Sebtide and Ghomaride superposed tectonic complexes formed by Paleozoic, Mesozoic and Cenozoic rocks, which are strongly affected by the Alpine Orogeny and have their equivalents in the Betics, called Alpujarride and Malaguide. Some of these complexes have undergone metamorphism and have been thrust over the Flysch Units and the External Zone in the Rif. Figure 2: Seismicity recorded by the Spanish IGN included in the 1994, 2004 and 2016 seismic series from magnitude 2.0. Main tectonic features are displayed. The Flysch Units, which are mostly Tertiary sedimentary rocks with some locally ultrabasic rocks, constitute the sedimentary basin that separates the Internal and External Zones and is underlain by oceanic crust. They thrust southward across the External Zone, which is formed by Mesozoic and Cenozoic sedimentary rocks that are mostly unmetamorphosed or, in some cases, have a low degree of metamorphism. The Alboran Sea is primarily formed by Neogene and Quaternary sediments deposited on a basement that corresponds to the Internal Zone complexes [16]. Furthermore, Neogene to Quaternary volcanic rocks can be found in the central-eastern Alboran Sea and eastern Rif and Betics. The main alpine deformations in this area occurred throughout the Oligocene and Miocene and continue into the present. The earliest stages of deformation were partially simultaneous with the process of western migration of the Betic and Rif Internal Zones, coinciding with the opening of the Alboran Sea and forming the Gibraltar Arc during a period of severe weakening of the continental crust. The new Alboran marine area corresponds to the western end of the Algoro-Provencal Basin, which began to open at the end of the Oligocene [17], forming a new oceanic floor. In the Alboran Sea, the continental crust was markedly weaker and situated on the new oceanic floor on its eastern border. Subduction processes, combined with NNW-SSE convergence and regional compression of the Iberian and Nubian plates [18; 19; 20], resulted in significant deformation in the northern and southern borders of the earliest Alboran Sea. These processes developed the Gibraltar Arc, with the uplift of the Rif and Betic Cordillera, which were radially deformed [21] around the Alboran Sea and undergoing a regional E-W compression. Later, from the late Miocene, when the opening was nearly at its end ceasing the E-W compression, the general NNW-SSE compression was completely re-established [22]. The region then began to undergo folding (e.g., the Alboran Ridge anticline) and faulting (e.g., the Al Idrisi, Yusuf, Carboneras, Averroes, Jebha and Nekor faults, in addition to other minor faults). Since the Miocene, important NNE-SSW sinistral strike-slip fault systems crossing the Alboran Sea (Trans Alboran shear zone; [23]) were formed, such as the Carboneras Fault, coming from Almeria, Spain and the Nekor and Jebha faults, the last being renowned inland [24]. Later, the Al Idrisi and other conjugated NW-SE faults developed (e.g., the Averroes Fault), as well as some E-W faults and thrusts with a general ENE-SW strike. The upper Neogene and Quaternary sediments of the central and eastern Alboran Sea are affected by these deformations, whereas the western Alboran Sea undergoes mud volcanic tectonics [25]. This regional geodynamic setting continues into the present. Almost all the domains mentioned are present in the study area.