This image provided by NASA's MODIS instrument on board the Terra satellite shows volcanic ash and steam billowing from the Chaiten Volcano in southern Chile, drifting across Argentina and dissipating over the Atlantic Ocean, Saturday, May 3, 2008.(AP Photo/NASA)

Local residents are helped to board during evacuation operations following the eruption of the Chaiten volcano, in the locality of Chaiten, some 1,200 km south of Santiago on May 2, 2008. About 1,500 people had to be evacuated after the eruption, which caused a red alert in neighbouring regions of Chile and Argentina.(CHRISTIAN BROWN/AFP/Getty Images)

Lightning bolts appear above and around the Chaiten volcano as seen from Chana, some 30 kms (19 miles) north of the volcano, as it began its first eruption in thousands of years, in southern Chile May 2, 2008. Cases of electrical storms breaking out directly above erupting volcanoes are well documented, although scientists differ on what causes them. Picture taken May 2, 2008. (Carlos Gutierrez)

Lightning bolts appear above and around the Chaiten volcano as seen from Chana, some 30 kms (19 miles) north of the volcano, as it began its first eruption in thousands of years, in southern Chile May 2, 2008. Cases of electrical storms breaking out directly above erupting volcanoes are well documented, although scientists differ on what causes them. Picture taken May 2, 2008. (Carlos Gutierrez)

Lightning bolts appear above and around the Chaiten volcano as seen from Chana, some 30 kms (19 miles) north of the volcano, as it began its first eruption in thousands of years, in southern Chile May 2, 2008. Cases of electrical storms breaking out directly above erupting volcanoes are well documented, although scientists differ on what causes them. Picture taken May 2, 2008. (Carlos Gutierrez)

A cloud of smoke and ashes produced by intensified eruption of the Chaiten volcano are seen over Chaiten on Tuesday, May 6, 2008, in southern Chile. (AP Photo/La Tercera)

A dead cow lies covered by ashes from the Chaiten volcano at a road leading to the Argenroad to Argentina, near Chaiten, Chile, Tuesday, May 6, 2008. The eruption spewed incandescent material and blated ash some 20 miles (30 kilometers) into the Andean sky, forcing authorities to a complete evacuation of the area including the nearby town of Chaiten. (AP Photo/La Tercera, Alfredo Miranda)

A sculpture of the Chilean national hero Arturo Prat is seen covered with ash from Chaiten volcano, at Futaleufu public square, some 1,450 km (900 miles) south of Santiago, May 9, 2008. (REUTERS/Ivan Alvarado)

Chile's Chaiten volcano erupts in Chaiten, Chile, Sunday, May 4, 2008. (AP Photo/Santiago Llanquin)

An aerial view after the flooded Chaiten town in southern Chile June 3, 2008. Experts have said Chaiten Volcano could erupt at a less volatile pace for months and even years. Picture taken June 3, 2008. (REUTERS/Cristian Brown/Intendencia Region de los Lagos/Handout)

Smoke rises from Chaiten volcano at Chaiten, located some 1220 km (760 miles) south of Santiago May 4, 2008. (REUTERS/Ivan Alvarado)