La fracturación del borde sur de la depresión de Granada. (Discusión acerca del escenario del terremoto del 25-XII-1884)

Abstract

The southern edge of the Granada basin is delimited by faults trending in an E-W to N 100-120 E direction and others trending in the general direction of NNW-SSE and N 15-40 E. All of these faults have been active since the Upper-Miocene and strongly infiuenced the deposits of the Neogene and Quaternary materials. Later they were responsible for the enclosing and compartmentation of the basin. The formation of the Sierra Tejeda and Sierra Almijara reliefs are also due to these faults. Apart from vertical displacements the E-W faults also show strike-slip movements and these latter must have been active since the end of the Lower-Miocene, through the Middle-Miocene and perhaps up to and including the Terminal-Scrravallian. Since then , to the north of the sierras Tejeda and Almijara, there has been a continual process of subsidence along an axis. Within this zone the lignites of Arenas del Rey were formed. This axis of fracturing and subsidence would appear to have been responsible for the earthquake on 25th December 1884. The compression directions during the Upper-Quaternary have been N 20 W and almost E-W and were accompanied by significant vertical displacements.