After we dealt with some faults in Greece, let’s move to Spain. The Ventas de Zafarraya Fault (VZF) west of the Granada basin (36.96° N, 4.14°W) has a beautiful morphologic expression and an exciting history. The fault bounds the Zafarraya polje to the south, with Quaternary sediments to the north (hanging wall) and limestones of the Internal Subbetics in the footwall.
The E-W trending normal fault has an average dip of 60° to the north and is visible for at least 15 km. A nice limestone fault scarp with up to 2 m height can be found in the central area. The VZF is famous for the “Andalusian Earthquake” which occurred on Christmas Day 1884 (Udias & Munoz, 1979). Several villages were destroyed severly (among them are Zafarraya, Arenas del Rey and Alhama de Granada) and hundreds of people died. Epicentral intensities reached MSK X. “A complex pattern of surface cracks, landslides, rock falls, liquefaction, and the change of spring-water chemistry [have been] associated with the seismic event.” (Reicherter et al., 2003, p.912).
Paleoseismological trenching studies allowed to estimate a magnitude of 6.5 for the Christmas event. However, four events are proposed within the last 9 ka (Reicherter, 2001). Besides GPR studies for imaging sediment deformation, trenches were opened for a detailed fault analysis.
A sketch illustrates the sediment features found with GPR measurements:
Some people say Picasso’s sister Dolores was born on this day prematurely because her mother was so shocked by the catastrophe.
References:
Udias, A & Muñoz, D. (1979). The Andalusian Earthquake of 25 December 1884. Tectonophysics 53, 291-299.
Reicherter K. (2001). Paleoseismologic advances in the Granada basin (Betic Cordilleras, Southern Spain). Acta geologica hispanica, v. 36 (2001), n° 3-4, p. 267 – 281.
Reicherter K., Jabaloy A., Galindo-Zaldívar J., Ruano P., Becker-Heidmann P., Morales J., Reiss S. & González-Lodeiro F. (2003). Repeated palaeoseismic activity of the Ventas de Zafarraya fault (S Spain) and its relation with the 1884 Andalusian earthquake. Int J Earth Sci (Geol Rundsch) (2003) 92:912–922.
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