The Instituto Geofísico del Perú has reported a series of small explosive eruptions on Mount Ubinas, a small but highly active volcano in the southern Peruvian Andes. The initial eruption occurred on Sunday 1 September 2013, and further events occurred on the following two days. However the eruptions are thought to be entirely phreatic in origin, caused by water percolating down from the surface and encountering hot rocks rather than by magma rising from bellow. The area has received a heavy snowfall in the last few days.
Small plume on Mount Ubinas on 2 September 2013. Instituto Geofísico del Perú.
The volcanoes of the Peruvian Andes, and of South America in general, are fueled by the subduction of the Nazca Plate beneath the South American Plate. The Nazca Plate underlies a large chunk of the eastern Pacific Ocean, and is being subducted along Peru-Chile Trench to the west of South America. As it sinks into the Earth, the Nazca Plate passes under South America, where it is heated by friction with the overlying South American Plate and by the heat of the planet's interior. This causes the Nazca Plate to partially melt, and some of this melted material then rises through the South American Plate as magma, fueling the volcanoes of the Andes. The motion of one plate beneath another is not a smooth process, and the Nazca and South American Plates frequently stick together, then break apart as the pressure builds up, triggering frequent Earthquakes along the western coast of South America, and sometimes further inland.
The approximate location of Mount Urbinas. Google Maps.
See also Further eruptions on Mount Tungurahua, 200 people evacuated after eruption on Tungurahua, Eruptive activity on Mount Sabancaya, Eruption on Mount Copahue and Eruption on Volcán El Reventador.
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