The Puyehue (poo-YAY-way) volcano in Chile is presently in an eruptive phase. This stratovolcano is part of the Puyehue-Cordón Caulle Volcanic Complex (PCCVC). The Andean Cordillera is zoned with isolated volcanic belts along the length of the continent.  As is the case along the rest of the Ring of Fire around the Pacific rim, the vulcanism is due to subduction, in this case of the Nazca and Antarctic plates.
Eruption of Puyehue Volcano in Chile (photo AFP)

It was suggested (tongue in cheek) that the volcano be renamed Mount Doom from the Lord of the Rings.

Puyehue Eruption, June 2011. (Earth Observatory)Puyehue Eruption (June 14, 2011, Earth Observatroy)

 Today’s image (below) from the Earth Observatory is telling of the scale of the ash cloud. It has traversed the width of the continent due east- from the Andea’s on the Pacific to the Atlantic and beyond.

Puyehue Eruption 6/14/11 (Earth Observatory photo)