Abstract: Altogether about 2500 volcanoes exist on Earth, and during the last 3500 years, 959 of them erupted. About 360 mln. people live in dangerous proximity to actve volcanoes. On average about 50 volcanoes erupt each year. Catastrophic events may result from six volcanic processes, viz. 1) ejection of rock debris; 2) lava flows; 3) ejection of volcanic gases; 4) burning volcanic clouds; 5) volcanic landslides; 6) lahars. Each eruption manifests itself in several volcanic processes, but only one or two of them may prevail. First of all volcanic eruptions are dangerous for the following human activities: 1) transportation; 2) agriculture; 3) communication & electricity transmission lines; 4) residential building. Average annual mortality from them is about 800 persons and economic loss amount to $800-900 million.