The Tungurahua volcano spews ash and stones during an eruption as seen from Cotalo, Ecuador, Saturday April 30, 2011.  Tungurahua hurled truck-sized pyroclastic boulders more than a mile in a powerful eruption that prompted at least 300 people to flee their homes, authorities said. The volcano, some 85 miles southeast of Quito, has been active since 1999. (AP Photo/Dolores Ochoa)

The Tungurahua Volcano spews ash and stones while it erupts, as seen from Cotalo, Ecuador, Friday, April 29, 2011. The Tungurahua volcano, 136 kilometers, some 85 miles, southeast of Quito, has been active since 1999. (AP Photo/Dolores Ochoa)