Cuicocha volcano (3246m) is located at the south of Cotacachi volcano and lies about 100km north of Quito. It is thought that eruptive activity began at Cuicocha about 4500 years ago but the volcano has not since erupted for over 1000 years. The last major explosive eruption was c. 3100 years ago, erupting 5km3 of pyroclastic material (flow and fall) covering wide areas around the low-rimmed caldera. The caldera itself is 3km wide, has steep walls and contains a lake almost 150 m deep. There are four distinct intra-caldera lava domes which form two steep forested islands. Gases continue to be emitted from several locations around the caldera lake with very slight annual temperature increases on an annual basis.