Repeated Palaeoseismic Activity of the Ventas De Zafarraya Fault (S Spain) and Its Relation with the 1884 Andalusian Earthquake
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Int J Earth Sci (Geol Rundsch) (2003) 92:912–922 DOI 10.1007/s00531-003-0366-3 ORIGINAL PAPER K. R. Reicherter · A. Jabaloy · J. Galindo-Zaldvar · P. Ruano · P. Becker-Heidmann · J. Morales · S. Reiss · F. Gonzlez-Lodeiro Repeated palaeoseismic activity of the Ventas de Zafarraya fault (S Spain) and its relation with the 1884 Andalusian earthquake Received: 10 December 2002 / Accepted: 2 September 2003 / Published online: 14 November 2003 Springer-Verlag 2003 Abstract One of the most destructive historical earth- reported. The epicentre was probably located in the quakes (M 6.7) in Spain occurred in 1884 along the triangle between Arenas del Rey, Alhama de Granada and normal Ventas de Zafarraya Fault located in the Central Ventas de Zafarraya according to the macroseismic Betic Cordilleras. Palaeoseismic and radiocarbon data pre- information (Fig. 1). The maximum intensity was X sented in this study are the first to constrain the timing of (MSK scale) from which a magnitude of between 6.1 the pre-1884 fault history in the last 10 ka. These data (Lpez Casado et al. 2000) and 7 (Muoz and Udas yield a recurrence interval of between 2 and 3 ka for major 1980) has been calculated. European commissions studied earthquakes, under the assumption of uniform return pe- the geology of the region and the effects generated during riods along the normal fault. The Holocene slip rate is or after the earthquake (Orueta and Duarte 1885; estimated to be in the order of 0.35€0.05 mm/year, which Taramelli and Mercalli 1886; Kilian 1889; Muoz and is significantly higher than the mean slip rate of 0.17€ Udas 1980 and references herein). They described an 0.03 mm/year since the Tortonian. Several of the most area of a complex pattern of surface cracks (Fig. 2), important deformations and secondary features, such as landslides, rock falls, liquefaction, and the change of landslides and liquefaction, are related to strong ground spring-water chemistry associated with the seismic event. motion and document the Holocene activity of the Ventas The international collaboration resulted in the reconstruc- de Zafarraya Fault. tion of the new village of Arenas del Rey with one of the first earthquake-safe city designs. Although no unambiguous fault-related rupture at the Introduction surface or coseismic movements along the fault plane were recognized, Muoz and Udas (1980) and Sanz de The most destructive earthquake of the Iberian Peninsula Galdeano (1985) concluded that the earthquake has during the last 150 years occurred on 25 December 1884 possibly been associated with several faults and tectonic at 21:08 h (‘Terremoto de Andaluca’, Fernndez de blocks along the northern margin of the Sierra Tejeda Castro et al. 1885, in: Muoz and Udas 1980). More than (Fig. 3). 800 casualties and several destroyed villages were Here we characterize, palaeoseismologically, the Ven- tas de Zafarraya Fault (VZF) in order to establish its K. R. Reicherter ()) · S. Reiss relationship with the 1884 earthquake and with previous Institut fr Geophysik, Universitt Hamburg, coseismic events along the same normal fault. Our Bundesstraße 55, Hamburg, Germany investigations include sedimentology, microstratigraphy, e-mail: [email protected] radiocarbon dating, as well as an evaluation of aerial and Fax: +49-40-428385441 satellite photos, and an assessment of the recent and A. Jabaloy · J. Galindo-Zaldvar · P. Ruano · F. Gonzlez-Lodeiro historical seismicity. We applied high-resolution ground- Departamento de Geodinmica, penetrating radar (GPR), to describe and characterize the Universidad de Granada, sub-surface expression of the VFZ in the hanging wall. Campus Fuentenueva, Granada, Espaa The Betic Cordilleras in southern Spain are located within the Eurasian–African Convergence Zone in an P. Becker-Heidmann Institut fr Bodenkunde, Universitt Hamburg, approximately 500-km-wide region with a disperse seis- Allende-Platz 1, Hamburg, Germany micity. In the last few years, intense work on the palaeoseismicity of individual faults in the Betic Cordil- J. Morales leras started. Several structures along active fault zones in Instituto Andaluz de Geofsica, Universidad de Granada, the Betic Cordilleras are related to coseismic surface Granada, Espaa 913 Fig. 1 a Geological setting. General map of the Betic Cordillera plexes; 8 Alpujrride Complex; 9 Nevado-Filbride Complex; 10 (legend see b). b Map of study area. 1 Upper Miocene–Quaternary Iberian Massif with cover rocks; 11 isoseists of the 1884- sedimentary rocks; 2 Subbetic unit (the entire subbetic zone in a); 3 earthquake; 12 macroseismic intensity of the 1884-earthquake Internal subbetic; 4 Prebetic; 5 Oligocene–Lower Miocene sedi- source; 13 unconformity; 14 fault; 15 normal fault; 16 reverse fault; mentary rocks including flysch and olistostroms; 6 Campo de 17 syncline, 18 anticline. Inset shows locality of Fig. 2 Gibraltar Flysch; 7 Predorsalian, Dorsalian and Malguide Com- Fig. 2 Topographic map of the scarp of the Ventas de Zafarraya cemetery of Ventas de Zafarraya, locality 2 Cortjo del Barranco, Fault. Topographic lines every 50 m; master topographic lines locality 3 Pilas de Algaida every 250 m. Note locality of radar-lines in Fig. 6. Locality 1 914 Fig. 3 Digital elevation model of the study area showing the 1884 rupture (Fig. 2). AD Al- born Domain; IEZB internal external zone boundary; ZP Zafarraya Polje; SID South Iberian Domain. Note landslide of Pilas de Algaida and locality of Fig. 8. The trace of the IEBZ is covered by Quaternary de- posits and projected, hence, it seems not to be displaced by the VZF rupturing (see summary in Masana and Santanch 2001). Zone is locally overlain by nappes of the Campo de The Alhama de Murcia fault zone was investigated by Gibraltar Flysch units (Fig. 1). The Internal–External Silva et al. (1997), Martnez-Daz et al. (2001), and Zone Boundary (IEZB) separates the Internal Zones from Masana et al. (2003). The Carboneras Fault Zone in the the External Zones. The IEZB forms a low angle province of Almera has been studied by Bell et al. (1997) detachment (N50E strike and 25 dip to NW) in the and Reicherter and Reiss (2001). A description of active studied area with a top-to-the-W sense of movement faults in the Granada depression was provided by (Galindo-Zaldvar et al. 2000). Towards the west it bends Reicherter et al. (1999), Alfaro et al. (2001) Reicherter into an E–W direction. In the studied area, the VZF cuts (2001) and, recently, by Galindo-Zaldvar et al. (2003). the Internal–External Zone Boundary (IEZB) of the Betic The stratigraphic relationships along the active VZF Cordilleras (Lonergan et al. 1994). permit the reconstruction of the faulting history, including The normal VZF strikes WNW–ESE and dips towards the number and relative size of faulting events, and the NNE at an angle of 60 and is associated with a prominent determination of recurrence intervals (e.g. Wallace 1986; scarp in Jurassic limestones. The fault can be divided into McCalpin 1996). two E–W-oriented sectors separated by a central NW–SE- oriented sector. The striations on the fault plane indicate a main normal slip component with a minor dextral strike- Geological setting slip component (superposed striae with a rake of 12E and 27E). The present-day stress field indicates a NW–SE- The South Iberian Domain or External Zone is made up of directed maximum horizontal compression direction almost 1,000 m of Liassic white limestones and grey (Herraiz et al. 2000), and a SW–NE-directed extension, dolostones, followed by approximately 500 m of marly which is in concordance to the observed kinematic limestones and limestones of Middle Jurassic to Late indicators on the fault plane. Cretaceous age (Garca-Hernndez et al. 1980). The karstified Zafarraya Polje (Figs. 1, 2 and 3) is filled with alluvial and colluvial deposits of Quaternary age; under- Seismological setting lying Tortonian calcarenites have been drilled. The area of subsidence within the Zafarraya Polje is asymmetric The present-day stresses in the studied area and the (Ollero and Garca 1984). The small basin is bound to the Granada depression (Fig. 1) were determined by focal south by the normal VZF and forms a half-graben mechanism solutions. It is characterized by a NE–SW associated with an extensional roll-over structure, as extension (Galindo-Zaldvar et al. 1993, 1999). However, indicated by seismic and gravimetric data (unpublished the stress field in the area is heterogeneous as documented data of Galindo-Zaldvar). by permutations of the stress axes. Essentially, radial The Alborn Domain or Internal Zone, is deformed by extension, NE–SW extension, and NW–SE subhorizontal extensional detachments during the Mid-Miocene (Fer- compression are observed; the latter is parallel to the nndez-Fernndez et al. 1992; Martnez-Martnez and shortening direction active under the regional tectonic Azan 2002). Low- to high-grade metamorphosed stress field (Buforn et al. 1988; DeMets et al. 1990; schists and marbles form the Alpujrride Complex, Galindo-Zaldvar et al. 1999). whereas the Malaguide Complex includes Variscan The seismic activity in the Granada depression and basement covered by Mesozoic sediments. The Internal surrounding areas is characterized by frequent micro- 915 Fig. 4 Historical seismicity in Andalucia (after Reicherter 2001). Recent seismicity from NEIC data (http://neic.usgs.gov/ neis/epic/epic.html) earthquake activity (MW 3.0, Fig. 4). The occurrence of series and seismic swarms is frequently observed, affect- ing the depression (Vidal 1986; Posadas et al. 1993; Serrano 1999; Saccorotti et al. 2001). The depth of this shallow activity ranges between 5 and 15 km to a maximum of 20 km and includes earthquakes with MW 5 or more. The last moderate event occurred to the south of the Granada depression with MW =5.0 in 1984 (Morales et al.