Mount Sinabung spews volcanic materials into the sky in Indonesia today. The volcano, dormant for more than four centuries, has erupted two days in a row, forcing the evacuation of thousands of people who live along its slopes.

TANAH KARO, Indonesia -- An Indonesian volcano that had been dormant for more than four centuries erupted for the second day in a row today, spewing white clouds of smoke and ash more than 2,000 yards into the air, officials and witnesses said.

Thousands of people living along the slopes of Mount Sinabung in North Sumatra province have been evacuated to emergency shelters, mosques and churches, said Priyadi Kardono, a spokesman for the National Disaster Management Agency.

Their abandoned villages and crops are blanketed in heavy, gray soot.

Mount Sinabung last erupted in 1600, so observers don't know its eruption pattern and are monitoring it closely for more activity.

Indonesia, the world's largest archipelago, is on the so-called "Ring of Fire," an arc of volcanos and fault lines encircling the Pacific Basin.