SANTIAGO, CHILE - The long-dormant Chaiten volcano blasted ash about 20 miles into the Andean sky Tuesday, forcing thousands to evacuate and fouling a huge stretch of the South American continent.

The thick column of ash climbed into the stratosphere and blew eastward for hundreds of miles over Patagonia to the Atlantic Ocean, forcing schools and a regional airport to close. People in Chile and Argentina were advised to wear masks to avoid breathing the dangerous fallout.

The five-day-old eruption is the first in at least 9,000 years for the volcano in southern Chile, according to volcanologists at the Smithsonian Institution in Washington.

Chilean officials ordered the total evacuation of Chaiten, a small provincial capital in an area of lakes and glacier-carved fjords just six miles from the roiling cloud.

Also emptied was the soot-coated border town of Futaleufu, about 75 miles from the volcano.

The gritty, gray-white blizzard covered houses, roads and cattle. People wrapped cloths around their faces and wore surgical masks as they slogged through the mess.

About a half-inch of ash coated the Argentine tourist town of Esquel, a Patagonian resort favored by backpackers and skiers at the foot of the Andes whose airport and schools have been closed since Saturday.

Volcanologist Juan Cayupi told The Associated Press by telephone that Chaiten's two small craters have morphed into a large crater, and that "a large amount of ash, particles, gas" is pouring out.