Volcano Eruptions - through 2010
According to the Smithsonian Institute's Global Volcanism Program, there are probably about 20 volcanoes erupting right now, and about 550 volcanoes have had historically documented eruptions. A volcano is an opening, or rupture, in the Earth's crust through which molten lava, ash, and gases are ejected. Volcanoes typically form in three different settings. The first is divergent plate boundaries, where tectonic plates are pulling apart from one another, such as the Mid-Atlantic Ocean Ridge. Most of these volcanoes are on the bottom of the ocean floor and are responsible for creating new sea floor. The second location is convergent plate boundaries, where two plates, typically an oceanic and continental plate, are colliding. The volcanoes along the Pacific Ring of Fire are from convergent plate boundaries. The third location is over hotspots, which are typically in the middle of tectonic plates and caused by hot magma rising to the surface. The volcanoes on Hawaii are the result of hotspots.
There are three datasets that highlight global volcano locations. This dataset is from the National Geophysical Data Center's Significant Volcanic Eruption Database and shows the locations of significant eruptions, of which there are over 400. An eruption if considered significant if there are any fatalities linked to it, the cost of the damage is over one million dollar, it causes a tsunami, or there is a major earthquake associated with it. Also available from NGDC is a dataset showing the locations of volcano eruptions causing tsunamis. The last dataset, Volcano Locations Globally from the Smithsonian Institute's Global Volcanism Program, illustrates the locations of current and past activity for all volcanoes on the planet active during the last 10,000 years.
- Most volcanoes occur along convergent boundaries
- There have been about 1300 know eruptions in the last 10,000 years
- There have been over 400 significant eruptions
- There have been 110 eruptions that caused tsunamis