Around 30 000 people have been evacuated from homes in communities close to Mount Urbinas, a small but highly active volcano in the southern Peruvian Andes, generally considered to be Peru's most active volcano, following a series of explosive eruptions that began on Thursday 18 July 2019. The first of these eruptions produced an ash column about 5 km high, and led to ashfalls in communities 25 km from the volcano, prompting the volcano. The evacuees have been relocated to shelters outside the volcano's danger zone, as part of a predetermined emergency plan.
The volcanoes of the Peruvian Andes, and of South America in general, are fuelled 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, fuelling 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 subduction of the Nazca Plate beneath the South American Plate, and how it causes Earthquakes and volcanoes. Pacific Earthquake Engineering Research Center.
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