Alert level orange at Nevado del Ruiz volcano, Colombia

In 1985, an eruption at Nevado del Ruiz in Colombia triggered deadly mudflows - lahars - that killed more than 20,000 people. That volcano is showing signs of life once again.

Although the 1985 eruption was not huge - about 1/30 the amount of magma as Mt. St. Helens in 1980 - the mountain is covered with glaciers. The pyroclastic flows (glowing hot, fast…