<P> Reventador is an active stratovolcano which lies in the eastern Andes of Ecuador . Since 1541, it has erupted over 25 times, with its most recent eruption in 2009, but the largest historical eruption occurred in 2002 . During that eruption, the plume from the volcano reached a height of 17 km, and pyroclastic flows went up to 7 km from the cone . On March 30, 2007, the mountain spewed ash again . The ash reached a height of about two miles (3 km, 11,000 ft). </P> <P> Cotopaxi, outside of Quito, started activity in April 2015 . A large increase in earthquakes (including harmonic tremors) and SO emissions began . IGPEN reported slight deformation of the edifice, suggesting an intrusion of magma under the volcano . As of 25 July, the unrest continued, and the most recent major eruption was an ash and steam eruption that occurred on August 14 and 15, 2015 . </P> <P> Volcanoes in Peru are monitored by the Peruvian Geophysical Institute . </P> <P> Sabancaya is an active 5,976 - metre (19,606 ft) stratovolcano in the Andes of southern Peru, about 100 kilometres (62 mi) northwest of Arequipa . It is the most active volcano in Peru, with an ongoing eruption that started in August 2014 . </P>

List of volcanic eruptions in the ring of fire