Masaya is one of 18 distinct volcanic centers that make up the Nicaraguan portion of the Central American Volcanic Belt (CAVF). Formed by the subduction of the Cocos Plate beneath the Caribbean Plate, along the Mesoamerican trench, the CAVF runs from volcán Tacaná in Guatemala to Irazú in Costa Rica. In western Nicaragua, the CAVF bisects the Nicaraguan Depression from Cosigüina volcano in the northwest to Maderas volcano in Lago Nicaragua. The Interior highlands to the northeast make up the majority of Nicaragua. Western Nicaragua consists of 4 principal geological provinces paralleling the Mesoamerican trench: 1. Pre-Cretaceous to Cretaceous ophiolitic suite; 2. Tertiary basins; 3. Tertiary volcanics; and the 4. Active Quaternary volcanic range.