Soldiers were sent to clear ash from towns and roads near Chile's Calbuco volcano, which was quieter but continued to release columns of ash days after emitting twin spectacular eruptions.

Late Sunday, Chile's National Geology and Mining Service said rainfall in the coming days could cause dangerous lahars, mudflows of debris, pyroclastic material and water that would flow down the volcano's slopes and through valleys. Experts also said they feared the rain could cause the thick layer of volcanic ash to harden in place.

About 400 soldiers arrived in the region to help residents clean the ash off roofs and from streets and properties.

The area looks like a "gray desert," said 45-year-old local Victor Hugo Toledo.

"Wherever you look all you see is gray dust; there is an average of 50 centimeters off it over the towns and on all the roofs," he said.

Officials are urging people to keep using masks or handkerchiefs to prevent breathing in dust.

More than 6,000 people have been evacuated and authorities are maintaining a 12-mile (20-kilometer) exclusion zone around the volcano.

At the foot of the volcano, authorities have allowed some of the 1,500 people who evacuated the town of Ensenada to return temporarily to their homes to carry out belongings and clean up damage from the heavy ash fall.

The affected area is about 620 miles (1,000 kilometers) south of Chile's capital, Santiago.

Calbuco roared back to life Wednesday afternoon, after lying dormant since a minor eruption in 1972. It billowed ash about 11 miles (18 kilometers) high in the initial blast, then several hours later produced a second, spectacular outburst that turned the nighttime sky reddish orange and caused huge lightning bolts to crackle through its ash plume.