Planchón-Peteroa is a complex volcano

Complex volcano

A complex volcano, also called a compound volcano, is a volcano with more than one feature. They form because changes of their eruptive characteristics or the location of multiple vents in an area...

 extending in a north-south direction along the border between Argentina

Argentina

Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

 and Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

. It consists of volcanoes of various ages with several overlapping caldera

Caldera

A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...

s. Those include Volcán Planchón, Volcán Peteroa and Volcán Azufre.

A partial collapse of the complex about 11,500 years ago produced a major debris avalanche, which followed the course of the Teno River

Teno River

The Teno River is a river located in the Maule Region of central Chile. It begins at the confluence of the Malo and Nacimiento rivers. The former originates north of Planchón volcano at Lagunas de Teno. The river flows initially northwest across the Andes...

 until reaching the Chile Central Valley.

Peteroa has a crater lake

Crater lake

A crater lake is a lake that forms in a volcanic crater or caldera, such as a maar; less commonly and with lower association to the term a lake may form in an impact crater caused by a meteorite. Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not...

. Lagunas de Teno lies at the foot of Planchón volcano. In this area also is the Vergara International Pass.

September 6, 2010 eruption

Planchón-Peteroa Volcano erupted on September 6th followed by a stronger eruption on September 18th. On September 21st, the volcano erupted once again emitting a dark gray plume of ash. Planchón-Peteroa is located on the border between Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

 and Argentina

Argentina

Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

, as volcanic ash

Volcanic ash

Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...

 is being blown southeast into Argentina. Residents of Argentina were warned by authorities to evacuate before Planchón-Peteroa would erupt again.

See also

• List of volcanoes in Argentina
• List of volcanoes in Chile
• Descabezado Grande
  Descabezado Grande
  Descabezado Grande is a stratovolcano located in the Maule Region of central Chile. It is capped by a ice-filled caldera and named for its flat-topped form, as descabezado means "headless" in Spanish...
  
  
• Las Leñas
  Las Leñas
  Las Leñas is one of the largest Andean ski resorts in Argentina, located in the western part of Mendoza Province, together with Cerro Catedral in San Carlos de Bariloche, located in Rio Negro province....