Volcanic eruptions may be dangerous and destructive. They are capable of ejecting hot tephra clouds from the top or side of a volcano. As they whiz down steep slopes, these searing storms obliterate nearly everything in their path. Volcanic ash that is launched into the air will ultimately fall back to Earth, much like snow does. Ash may suffocate plants, animals, and people if it builds up to a sufficient height. Mudflows can develop in the presence of cold water, such as that found in streams or the melting of snow and ice. Near erupting volcanoes, mudflows (also known as lahars) have buried entire villages. The most active volcano on Earth is erupting for the first time in 38 years, terrifying scientists and the entire globe.