Active faulting in the internal zones of the central Betic Cordilleras (SE, Spain)

The internal zones of the Betic Cordilleras show a present-day relief that is mainly controlled by kilo- metre-size, symmetrical or north-vergent folds which developed mostly since Middle Miocene times. The Sierra Nevada, Sierra Alhamilla, Sierra de Los Filabres, Sierra Tejeda and Sierra de Gador, among others, are roughly E-W trending high mountain ranges, corresponding to antiforms where metamorphic rocks crop out. The surrounding depressions are located in synforms, where Neogene rocks are preserved from erosion. Field evidence shows that the growth of the folds is coeval with fault development, and that at least three of them, i.e. the Padul Fault, the Zafarraya Fault, and the Balanegra Fault, may be considered to be active seismogenetic structures. The Zafarraya Fault, in particular, is thought to be responsible for the 1884 Andalucia Earthquake. The fault is located at the northern limb of the Sierra Tejeda antiform, and could be interpreted as a collapse structure developed along the external arch of the uplifted fold. The Padul and Balanegra faults are located at the southeastern border of the Granada Basin and south of the Sierra de Gador, respectively. They belong to a set of NW-SE oriented faults that are mainly normal in character and indicate NE-SW extension. The set up, since 1999, of a GPS network within and around the Granada Basin and the planed installation of a new network in the Sierra Tejeda, will give us new insights on the present-day deformation behaviour of both folds and faults in the area.