Usulután volcano is a stratovolcano in east-central El Salvador, at the SE end of a cluster of basaltic to basaltic-andesite stratovolcanoes between San Vicente and San Miguel volcanoes.
The volcano contains a broad 1.3-km-wide summit crater breached to the east. The flanks of the forested Usulután volcano are strongly eroded and suggest a long repose interval, but young lava flows are present on its southern flanks. They are probably less than 10,000 years old. Cerro Nanzal is a flank cone on the lower SE flank and was mapped as Holocene.