Overview of the Tectonics and Geodynamics of Costa Rica

Abstract

Although Costa Rica is a relatively small region along the Central American Volcanic Arc (CAVA), its fascinating geology records several interesting examples of recent arc evolution. The forearc at present is in a state of subduction erosion, ranging from ‘moderate’ long-term rates of ~100 km3/km/Ma beneath Nicoya Peninsula to ‘extreme’ short-duration peaks of ~1,000 km3/km/Ma beneath Osa Peninsula. The margin is currently both seismogenic and tsunamogenic, with seismicity in the Osa Peninsula nucleating along one of Earth’s shallowest seismogenic plate interfaces. In Costa Rica, arc volcanism has created much larger volcanic edifices than it has northward along the CAVA. Forearc deformation is ongoing and active, and associated with large-scale erosion and sediment transport towards the trench that is currently being almost entirely trapped in forearc basins prior to the trench axis. Margin evolution is also strongly linked to documented spatial and temporal variations in the incoming Cocos and Nazca Plates. These conditions have had significant consequences for the geochemical evolution of the CAVA in Costa Rica, so that Costa Rica’s active geology records one of Earth’s most diverse and interesting volcanic arcs.