GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.1 GNGTS 2023 Geology and Tectonics of El Salvador El Salvador is located in the Central American Volcanic Arc (CAVA) that extends from Guatemala to Costa Rica along the active Pacific margin, where the Cocos plate subducts beneath the Caribbean plate in the Middle American Trench, taking place at about 7 cm/year (Dewey and Suarez, 1991). The volcanic arc ends to the north in Guatemala in a diffuse triple junction between the Cocos, Caribbean, and North American plates (Canora et al., 2010) (see Fig. 1). The chain of Quaternary volcanoes, many of which are still active, is approximately parallel to the Pacific coast. Figure 1. Tectonic setting of El Salvador. El Salvador is affected by earthquakes from two main sources of seismicity: large earthquakes are generated in the Benioff–Wadati zones of the subducted Cocos plate; a further source of seismicity is given by a zone of upper-crustal earthquakes that coincides with the chain of Quaternary volcanoes that extend across the country from west to east. The earthquake of 13 January 2001 was generated by the first source, the Benioff-Wadati zone. From a geological standpoint, this northern part of CAVA is characterised by a continental-style crust with Paleozoic and even older rocks, overlain by Upper Paleozoic, Mesozoic and Tertiary