Natural Disasters: Volcanoes

Volcanoes are not randomly distributed over the Earth's surface. Most are concentrated on the edges of continents, along island chains, or beneath the sea forming long mountain ranges. More than half of the world's active volcanoes above sea level encircle the Pacific Ocean to form the circum-Pacific "Ring of Fire." In the past 25 years, scientists have developed a theory -- called plate tectonics -- that explains the locations of volcanoes and their relationship to other large-scale geologic features.

 From Bradley, 1994, Volcanoes of the United States: USGS General Interest Publication

A volcano in the Puyehue-Cordon Caulle chain of south-central Chile erupted June 4 after lying dormant for more than 50 years.

Lightning: Ash particles generate static electricity as they move through the air.

One year after the eruption of Iceland's volcano Eyjafjajokull closed airports and stranded millions of travelers around Europe, Grimsvotn volcano erupts. 

http://earthobservatory.nasa.gov/

Unique twin ash plumes from Sinabung in Indonesia, erupting on August 29, 2010. [http://scienceblogs.com/eruptions/]

http://volcanoes.usgs.gov/hvo/ 

Includes maps, images, webcam from the USGS Hawaiian Volcano Observatory