Sumaco is an active stratovolcano east of Antisana, ca. 100 km east of Quito. It is an isolated mountain about 50 km east of the main volcanic range and rises 2800 m above the western Amazon basin. The volcano contains a 300 x 400 m wide summit crater with a central cone inside. There are 3 reports of eruptions in historic times, but only one eruption around 1895 is believed to actually have taken place.
Background:
Sumaco volcano was constructed on top of Cretaceous sedimentary rocks, far from the main volcanic front. Sumaco's lavas are different from those of the main Andean chain, and include alkaline tephritic, basanitic, and phonolitic rocks.
