Coatepeque De Coatepeque (Nahuatl cōātepēc, "at the snake hill") is a volcanic caldera in El Salvador in Central America. The caldera was formed during a series of major rhyolitic explosive eruptions between about 72,000 and 57,000 years ago. Since then, basaltic cinder cones and lava flows formed near the west edge of the caldera, and six rhyodacitic lava domes have formed. The youngest dome, Cerro Pacho, formed after 8000 BC.