Tunguragua volcano. Clouds of smoke rising from the erupting Tunguragua volcano. This mountain is 5023 metres high and it is one of Ecuador's most active volcanoes. It has erupted 25 times in the last 400 years. The eruption seen in the image began in September 1999. It caused the surrounding villages and farmland to be evacuated because of the danger of pyroclastic clouds (volcanic gas and ash). Volcanic eruptions are caused by magma (molten rock beneath the surface) being forced up a vent by pressure deep within the Earth. Photographed in October 1999.