## 3 Historical and Instrumental Seismicity in the Guadalquivir Basin  
Seismicity is not an outstanding process within the Guadalquivir Depression, however, important historical destructive events (\(\geq\)VIII EMS) have occurred in the zone along the northern border of the Neogene basin (Figure 1; Appendix A). In detail, aside from those events that occurred during the Islamic period, the city of Cordoba was the subject of an important seismic sequence during the late 19 th century (1863-1900). During this modern seismic period, maximum estimated intensities reached up to VI EMS [15] (IGN, 2022). Contrastingly, instrumental seismicity is not relevant (<4.0 mb; \(\leq\)V EMS) and it is mostly related to seismic series that occurred along the northern border of the basin between the  
Figure 2: Geologic and Geodynamic setting of the Archaeological site of Medina Azahara. (**A**): General sketch showing the lithospheric structure of the Betic foreland basin, flexural processes and related seismicity. Based in data from [17; 18] (not scaled). The cross-section displays the buried faults and stress tensors (\(\sigma\)1–\(\sigma\)2–\(\sigma\)3) deduced for recent focal solutions related with ongoing flexural process throughout the basin in the northern zone of the basin [18] (**B**): Geological cross-section displaying the structural arrangement of Paleozoic and Cenozoic materials beneath Medina Azahara. Based in the geological map of the zone [28] Vertical Exaggeration \(\times\)4.  
year 1945 and the present day [15]. However, more persistent and moderate instrumental seismicity (<4.5 mb; \(\leq\)VI EMS) is recorded along the southern Betic front of the basin [25; 26]. These southern events are mainly seismic swarms related to blind reverse and strike-slip faults within the basin [18; 25]. Figure 2A illustrate the location and kinematics of the northern and southern buried faults of the Guadalquivir basin in relation to the isostatic flexure of the zone, as proposed by some authors [18]. Regarding to historical seismicity, the more important events occurred during the lifetime of the caliphal city or soon after its abandonment, that is, during the second half of the 10 th century and from 11 th to 12 th centuries (Appendix A). Figure 3 illustrates the different historical seismic periods and events in relation to the construction, rise and fall of Medina Azahara. Two seismic periods between the years 944-957 CE (\(\leq\)VII MSK) and 971-974 CE (\(\leq\)VI-VII MSK), overlap the lifetime of the caliphal city (Appendix A; Figure 3). The last period occurred just before its sudden abandonment in the year 975 CE [5] (Figure 3) and the last event (974 CE) was strong enough to be felt in Extremadura (Coria) and Toledo about 300 km away [9]. Historical accounts on this earthquake describe: \"On Monday 21 st of Safar (Year of the Hijra 364 = 9 November, 974 CE), at the end of the midday prayer, an earthquake happened in Cordoba and its surrounding region, well perceived but of short duration. The tremor was felt at the same time in all the Andalusi regions. The police chief and military governor of the Jawf (Extremadura and its adjacent parts), [PERSON], wrote from the city of Coria reporting on this earthquake, as well as the exact date and hour of the event [32]. These two groups of earthquakes are well grounded on accounts by Arabic historians, with descriptions of slight building damage in Cordoba, especially those of the first seismic period [9; 10; 32]. However, these earthquakes do not seem to have sufficient destructive potential to promote the abandonment of the studied site, but maybe to cause some deformations and minor EAEs. However, other destructive earthquakes occurred in the zone after this period in the years 986-987 CE (\(\geq\)VII MSK), 1024 CE (VIII-IX MSK) and 1169 CE (IX-X MSK), strong enough to produce noticeable to important damage in the studied site (Appendix A; Figure 3).