Volcanic Hazards, Volcanic Catastrophes, and Disaster Mitigation

Volcanic eruptions have occurred since the Earth formed about 4.6 billion years ago. Each year, about 60 of the roughly 550 active volcanoes on Earth erupt. The frequency, magnitude, and type of eruptions of volcanoes are unlikely to change in the foreseeable future. One in every six of the active volcanoes on Earth (5% of all eruptions) has led to a loss of lives through its activity. About 260 000 people have died as a result of volcanic eruptions since A.D. 1600 (383) (Fig. 13.1). Cities and entire regions have been devastated. Disastrous volcanic eruptions are characterized by a rapid onset of their climactic phase and by a wide variety of eruptive behavior and effects: high and low temperatures, especially mass flows of different types (such as debris avalanches, pyroclastic flows and debris flows), but also including atmospheric transport of ash for hundreds of kilometers. During very powerful eruptions, huge masses of gases are injected into the stratosphere, forming aerosol veils that globally affect the climate and the ozone layer for years (such as following the Pinatubo eruption in 1991; Chap. 14).