Volcanic eruptions can be devastating and harmful. They have the ability to eject heated tephra clouds from a volcano's side or top. These scorching storms consume practically everything in their path as they race down steep slopes. As with snow, volcanic ash that is thrown into the air will eventually fall back to Earth. If ash piles up high enough, it can suffocate plants, animals, and people. In the presence of cold water, such as that found in streams or the melting of snow and ice, mudflows can form. Mudflows (lahars) have buried entire communities near erupting volcanoes. Scientists and the entire world are experiencing fear and worry as the largest active volcano on Earth is erupting for the first time in 38 years.