## 7 Discussion and Conclusions
Similar oriented patterns have been observed during recent instrumental earthquakes being possible to relate them to the primary arrival direction of surface seismic waves and earthquake source parameters [43; 46; 47]. Moderate earthquakes occurred between 971 and 974 CE (Appendix A) and were local events affecting the city of Cordoba [9; 10], but they can hardly be correlated with the observed damage. These events occurred during the last years of use of Medina Azahara as Caliphal residence, just before its relocation in Medina al-Zahira in the year 981 CE [36]. The 974 CE event was the only one energetic enough to damage the city as it affected the city of Cordoba and its surroundings, being felt in the whole Al-Andalus at such distant villages as Coria in Extremadura [9] about 300 km NW of Cordoba. Critical reviews on historical seismicity in Spain by [10], suggests that this is the unique event of this period that can be certainly located in Cordoba. The following 986-987 CE earthquake occurred during the early abandonment of Medina Azahara and it was described as strong enough to damage one of the bridges at Cordoba. However, this event is only documented in a work [33] and it is a doubtful earthquake not catalogued in the historical database of IGN and IAG. The AD 1024-1025 earthquake is considered \"the Great Earthquake of al-Andalus\" and it is listed in the IGN and IAG seismic catalogues with an intensity X MSK [8; 14; 15]. More recently, this earthquake is considered to have an intensity VIII-IX EMS (European Macroseismic Scale), with an estimated magnitude \(>\) 5.5 Mw [61] (Appendix A). This earthquake is documented in Arabic sources and its description includes collapse of mountains, violent ground movement and destruction of buildings [32; 62]. The fact that this event occurred under confusing socio-political circumstances during the _\"fithra\"_ (1009-1031 CE) may be the reason why it was overlooked by the local historians of Cordoba, resulting in its poor documentation. Of special significance is the fact that the Caliphal city was moved from Medina Azahara during 980-981 CE. Therefore, the 1024-1025 event occurred in an early abandonment stage of the city soon after its plundering by the Berber troops in 1010 CE (Figure 3). All these factors could conjugate to produce most of the oriented damage analyzed in this paper and contribute to the early ruin of the site. As suggested by modern archaeological excavations, the ruin levels correspond to the caliphal period which truly finished in 1031 CE (Figure 3). This ruinous state led to the use of this ancient city as a quarry for centuries, removing much of the archaeological evidence of earthquakes (EAEs). However, the remaining EAEs indicate a probable seismic origin, apparently produced by a unique event given the consistent oriented damage (N145\({}^{\circ}\)-150\({}^{\circ}\) E; Figure 19). In this sense, the 1169-1170 CE Andujar earthquake (X MSK) induced important damage and fatalities in the city of Cordoba (\(\geq\)VII MSK), as reported by contemporaneous Arabic accounts (see Section 3), so it can be considered as another probable damaging event for the site. Regarding the preserved remains, the probable seismically induced destruction of rich buildings (i.e., Abderrammian III Saloon; Figure 18) may have allowed the preservation of many of their luxurious decorative architectural elements (cooper, marbles, etc.) under the rubble, saving them from early robbery and centuries of plundering. Otherwise, these valuable elements would have been stolen, miss-sold and reused in former medieval buildings in Cordoba, the Islamic Iberia, or the entire Maghreb [63]. Collapse levels by earthquake damage would facilitate the preservation of valuable elements under the ruins of the historical heritage from the ancient Al-Andalus, allowing their recovery by the archaeological excavations carried out in Medina Azahara from the early 20 th century [5].