There are approximately 200 to 300 active volcanoes in South America and many of them are in the Andes Mountains.

On May 2nd, 2008, Chaiten volcano in Chile started to erupt and escalated on May 7th. By May 6th, over 4000 people were evacuated from the towns of Chaiten six miles southeast from the volcano and the town of Futaleufo which is 70 miles east. The last eruption of Chaiten was just over 9,300 years ago. Volcanoes are widespread in South America and have been divided up into regions called “arcs”.

The Andean Arc of Volcanoes

The Andean Arc covers the countries of Chile, Peru, Ecuador, and Columbia which includes 200 potentially active volcanoes. This area is seismically active due to the subduction of the Antarctic and Nazca plates below the South America plate. Where the angle of subduction is steep, that’s where the active volcanoes are occurring.

Volcanoes in the Andean Arc have been catalogued since 1532 and it is believed that approximately 25,000 people have been killed by over 600 volcanic eruptions. . There are only 25 volcanoes actively monitored in the Andean Arc.

Andean Arc Compared to World Volcanoes

South America has the highest number of volcanoes structures but Japan has the highest number of eruptions. Indonesia ranks behind Japan for the number of eruptions but it has the highest number of active volcanoes.

Within the Andean Arc, Chile has the highest number of active volcanoes numbering approximately 37 and it ranks 5th place in the world and Ecuador ranks 7th with 16 eruptions. Russia is in 4th place with 52 eruptions and Iceland is 6th place with 18 eruptions.

Historical Volcanic Eruptions in the Andean Arc

Nevado del Ruiz erupted in Columbia on November 13, 1985. More than 23,000 people were killed in Armero by volcanic debris. This was the highest death toll in South America.

Villarrica volcano, also known as Rucapillán is one of the most active volcanoes in the Andes. It has had 59 eruptions since 1558. In more recent times, it has erupted in 1948, 1963 and 1971 and has killed at least 75 people.

Current Volcanic Eruptions in the Andean Arc

Chaiten – Chile

Plumes of ash continue to be present since the original eruption on May 2, 2008. A large explosion occurred on May 7, 2008. Four more plumes have been discovered. A lahar (flow of rock and debris) triggered the flooding of the Chaiten River which damaged approximately 39 houses.

Ubinas – Peru

Ash plumes rose as high as 23,000 feet on May 9 and 12, 2008. This is Peru’s most active volcano and it is a young volcano. Historically, Ubinas has experienced minor explosions and avalanches since the 16th century. When part of the cone collapsed it caused an avalanche that spread for 7 miles.

Tungurahua – Ecuador

Ash and steam plums were spotted and rose as high as 26,000 feet. In addition, ash was falling within 5 miles of the volcano. On May 11th, noises were heard at the summit and rocks were rolling down the flanks. An explosion occurred on May 12th accompanied by more falling rock. This volcano is south of Quito which is the capital city and it is Ecuador’s most active volcano. In the past, it has had explosions and lava flows.

Pacific Ring of Fire

The Andes Arc is part of the Pacific Ring of Fire that spans the continents on both the east and west side of the Pacific Ocean. Over 90% of the world’s earthquakes occur in this area.

In addition, the world’s three worst earthquakes at Valdivia Chile (1960), Sumatra Indonesia (2004) and Prince William Sound Alaska (1964) were in the Pacific Ring of Fire. Although they were not the worst earthquakes in the world, there were two destructive earthquakes in San Francisco in 1906 and 1989.

Sources

US Geological Survey

Global Volcanism Program

Science Daily

Revista Geológica de Chile

Wikipedia