Abstract The Roman archaeological site of Baelo Claudia (Cádiz, south Spain) is located within the Gibraltar Arch, a region with no significant recent or historical seismicity. However, previous studies have emphasized the occurrence of repeated strong archaeoseismic damage (intensity≥IX MSK) at Baelo Claudia tentatively bracketed in this study around ad 40–60 and ad 260–290. A multidisciplinary study has been carried out including the detailed mapping of surface deformation and building damage, surface geology and geomorphology, collection of structural data, and an extensive ground penetrating radar (GPR) survey. The obtained data are not conclusive when considered separately, but evident links between archaeoseismic damage, structural and GPR data indicate that the destruction of the city was linked to seismic shaking. The analysis of the pattern and orientation of deformation clearly indicates SW–NE directed compression due to ground shaking. This analysis also focuses on localized landslides and liquefaction processes, which appear to be coeval with the earthquakes, but the poor geotechnical parameters of the clayey substratum were determinant to amplify the observed level of destruction. The application of the present Spanish seismic code (NCSE-02) indicates that intensity VIII MSK (0.24–0.26 g) can be reached in this zone for 500 year return periods.

Abstract The Betic and Rif cordilleras, lying to the north and south of the Alborán sea, form an arc-shaped mountain belt joining across the Straits of Gibraltar. The arc developed during, and partly in response to, late Mesozoic to Cenozoic convergence between Africa and Iberia. Three main pre-Miocene tectonic domains have been identified within the arc (Fig. 16.1a ). The first of these represents the palaeomargins of the southern part of the Iberian plate and the northern (Maghrebian) part of the African plate. Both palaeomargins comprise autochthonous, parautochthonous, and/or allochthonous non-metamorphic Mesozoic and Tertiary cover overlying a Variscan basement. These palaeomargins were deformed in response to Alpine events and now form the External Zones of the two cordilleras. The second major tectonic domain comprises deformed Cretaceous to Miocene deep-water ‘flysch’ sediments located in the western Betics and along the northern part of Africa from the Gibraltar Strait to the Kabylies (Fig. 16.1 ; e.g. Durand-Delga 1980 ). These ‘flysch’ sediments are thought to have been deposited in a basin located between the palaeomargins of Iberia and Africa and the rocks that form the internal part of the mountain belt ( Balanyá & García-Dueñas 1987 ). The third major tectonic unit is known as the Alborán domain or Internal Zones ( Balanyá & García-Dueñas 1987 ), and mainly comprises three nappe complexes of variable metamorphic grade, which are, from bottom to top, the Nevado-Filábride, the Alpujárride and the low-grade Maláguide complexes (Fig. 16.1 ). In addition, sedimentary rocks