Cotopaxi, outside of Quito started activity in April 2015, the volcano began to show signs of unrest, and came back to life. There was a large increase in earthquakes (including harmonic tremors) and SO2 emissions. 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.