Colachi

Colachi is a andesitic-dacitic stratovolcano that was constructed on an uplifted block of welded ignimbrites. The most recent activity produced pristine silicic lava flows of probable Holocene age, the largest of which covers a 7 km2 area on the saddle between Colachi and the neighboring volcano of Acamarachi (de Silva and Francis, 1991). A smaller flow was erupted on the W flank. The closely spaced Colachi and Acamarachi volcanoes represent different magmatic systems (Gardeweg 1993, pers. comm.).