## 2 Geological and Geodynamic Setting  
The ancient city of Medina Azahara is located in southern Spain (Andalusia), close to the city of Cordoba, on the boundary between the Paleozoic reliefs of Sierra Morena and the Neogene Guadalquivir sedimentary basin (Figure 1). Figure 1: Geological setting of the Caliphal City of Medina Azahara in the framework of the Guadalquivir Basin (SW Spain). Main faults and macroseismic epicenters of the most important historical earthquakes occurred in Al-Andalus between the years 940 CE and 1504 CE are showed (see Appendix A for seismic details). The Guadalquivir Neogene Basin corresponds to the foreland basin of the Betic Cordillera (Figure 1) and is filled by a thick sedimentary succession (c. 1.5 km) of Miocene to Pliocene marine deposits and olisthostromic units from the last c. 15.5 Ma [16]. To the south olisthostrome melange is imbricated and overridden by the proximal tectonic wedges formed by Triassic to Paleogene materials along the Betic thrust-front [17]. Tectonic loading along the Betic front and continuous sedimentation from 10.5 to 5.5 Ma caused significant lithospheric overloading triggering isostatic forebulging along the northern margin of the basin and the adjacent Paleozoic materials of the Iberian massif [17,18] (Figure 2A). Following these authors, Pliocene to Quaternary isostatic forebulging propagated to the North into the Iberian massif giving rise to flexural upfolding in the Paleozoic materials and relief generation (i.e., Sierra Morena). Upfolding also affected to the Miocene calacarenites along the northern margin of the Guadalquivir Depression facilitating its deformation and subaerial erosion. Nowadays, isolated patches of these eroded and uplifted Miocene materials lying unconformably on the metamorphic substratum provide evidence of the process (Figure 2B). Tectonic relief rejuvenation processes of the northern edge of the Guadalquivir basin have been described using geomorphological indexes and associated with the seismic activity of this fault [19, 20, 21, 22]. As illustrated in Figure 1, NNE-SSW to nearly N-S normal faults segment the trace of the NE-SW border of the Guadalquivir Basin, a complex erosive-mechanical contact historically known as the \"Great Betic Fault\" or the Guadalquivir Fault Zone (GFZ) [21,22]. The GFZ is a large fault-flexure fragmented (split) in multiple subparallel inducing the bending and upfolding of the Paleozoic basement for about 1500 m beneath the central sector of the basin to the northern reliefs of Sierra Morena [23]. This tectonic flexure induced the uplift of Sierra Morena which marks the southern end of the Iberian Paleozoic plateau generating an important topographic step and the uplift of the overlying Late Neogene materials [24]. Cartographic and geophysical data indicate that the uplift of the late Neogene calcarenites within the Sierra Morena range reach up to 420-450 m for the last c.a. 5 M.a. [17,24]. This accumulated uplift will indicate uplift rates of about 0.09-0.1 mm/year, sufficient to explain the seismicity of the zone [17,22]. Crustal bending promoted and assisted brittle deformation at upper crustal levels (<30 km) resulting in NNE-SSW to NE-SW normal faulting in the backbulge zone [18,25] delineating the northern border of the basin (Figure 2). Following these authors, these normal faults are the responsible of the instrumental seismicity along the northern border of the Guadalquivir basin (Figure 2A), but buried reverse faulting is also responsible of the variety of seismic series and swarms instrumentally recorded in the southern zone of the basin since the early 20 th century [18,25,26]. Research on the Andujar 1069-1970 CE [27] and Carmona 1504 CE historical earthquakes [21] also suggest that backbulge normal faulting along the NNE-SSW to NE-SW faults are the responsible sources of these historical events.