Seismicity and seismoactive faults of Cuba M.O. Cotilla Rodriguez a, * , H.J. Franzke b , D. Cordoba Barba a a Universidad Complutense de Madrid, Facultad de Ciencias Fisicas, Departamento de Fisica de la Tierra y Astrofisica I, Ciudad Universitaria, s/n, 28040 Madrid, Spain b Institut für Geologie und Paleontologie, TU Clausthal, Leibnizstrasse 10, D38678 Clausthal-Zellerfeld, Germany Received 20 January 2006; accepted 9 August 2006 Abstract The first catalogue of active regional faults of Cuba is presented. The seismotectonic map of Cuba is a base for studying the seismicity in this region. Of the 30 faults studied, only twelve are active. The main seismotectonic structure is the Bartlett-Cayman fault system, which borders the eastern and southeastern seismotectonic units in this region. Approximately 70% of Cuban seismicity is concentrated here. The Cauto-Nipe, Cochinos and Nortecubana faults border other seismotectonic units. The Nortecubana fault is the only one associated with a tsunami. All the faults are segmented. The faults described are related to the current tectonic stress regime of the Northern Caribbean. All the available information (maps, sections and profiles, photos, geological and neotectonic data on seismicity and focal mechanisms) is supported by a GIS. Keywords: Crust types; fault; microplates; neotectonics; seismicity; seismic hazard; Cuba Introduction The relative motion between the North American and Caribbean plates controls the tectonic regime of the area at a regional scale (Cotilla, 1993) (Fig. 1). It has been argued that the eastward motion of the Caribbean plate relative to the North American plate occurs at a rate of 12–40 mm/yr (Dixon et al., 1998; Deng and Sykes, 1995; DeMets et al., 1990; Sykes et al., 1982). DeMets et al. (2000) estimate 18±3 mm/yr for southeastern Cuba. This eastward motion of the Caribbean plate produces a left-lateral strike-slip deformation along the Bartlett-Cayman (BC) fault zone (Calais et al., 1992; Renard et al., 1992; Mann et al., 1984a) and left-lateral slips along the Walton-Plantain Garden-Enriquillo fault zone (Pubellier et al., 2000; Burke et al., 1980). Four important local structures affect the tectonic regime in the area (Fig. 1): 1) the Mid-Cayman rise spreading center (Rosencratz and Mann, 1991; Rosencratz et al., 1988; Case and Holcombe, 1980; Caytrough, 1979); 2) the Cabo Cruz basin; 3) the Santiago deformed belt (Calais and Mercier de Lepinay, 1992; 1990); 4) the Maisi area (Cotilla et al., 199la; Pubellier et al., 1991). These structures account for more than 85% of the seismicity along this part of the plate boundary (Cotilla et al., 1991a). Cuba is a megablock (or microplate) located in the southern part of the North American plate (Fig. 1) (Cotilla et al., 1991; Ladd et al., 1990; Lewis and Draper, 1990). The active plate boundary runs along the southeastern coast, where the main seismic activity follows the BC fault zone (Cotilla et al., 1997b; Calais et al., 1992; Mann and Burke, 1984). In this segment, faulting is mostly left-lateral strike-slip (Cotilla, 1998). The general pattern of seismicity in the Caribbean region is shown in Fig. 1. Large earthquakes occur along the plate boundary near Hispaniola, Jamaica and Puerto Rico (Fig. 2) (Pacheco and Sykes, 1992; Alvarez et al., 1990, 1985; McCann and Pennigton, 1990; Mann et al., 1984; Iniguez et al., 1975; Sykes and Ewing, 1965; Robson, 1964; Taber, 1922; Sherer, 1912), but since the 18th century no event has reached a magnitude of 7.0 (Fig. 3, A) (Cotilla, 1999; Cotilla and Udias, 1999). Low-magnitude seismicity (Ms < 4) occurs throughout the western region of the island and particularly around Santiago de Cuba (Fig. 3, B, C). The results in Cotilla et al. (1991a) suggest that Cuba is a seismotectonic province composed of four units (western, central-eastern, eastern and southeastern). Figure 4 shows the location of these units and their limits, three crust types (thick transitional, thin transi- tional and oceanic (Prol et al., 1993; Pusharovsky et al., 1987; Levchenko et al., 1976)) that compose the region, and some of the associated earthquakes. Figure 5 presents a simplified * Corresponding author. E-mail address: macot@fis.ucm.es (M.O.Cotilla) www.elsevier.com/locate/rgg Russian Geology and Geophysics 48 (2007) 505–522 © 2007, IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved. 1068-7971/$ - see front matter D 2007, IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.rgg.200 6.08.004