Volcanoes that geologists believe may be extinct are located in such diverse places as Japan, the northern Pacific Ocean, Germany, Peru, the Philippine Sea, Meares Island, the United States, the Netherlands, Australia, Tanzania, France and Russia. Extinct volcanoes are not concentrated in any specific locations.
Geologists define an extinct volcano as one that has not erupted in at least 10,000 years and no longer maintains access to an underground supply of magma to feed its eruptions. For example, the volcanoes that geologists believe created the Hawaiian Islands moved with the tectonic plates that took them away from their supply of magma and left them extinct. As the extinct volcanoes moved west, the magma supply gave rise to new volcanoes to carry the magma from inside the Earth to the surface.
Some volcanoes that technically met the definition for extinction status at one point have later erupted, including Soufriere Hills in Montserrat, which erupted in 1995, and Fourpeaked Mountain in Alaska, which erupted in 2004. Most famously, the presumed extinct Mount Vesuvius erupted in 79 A.D., when it destroyed the Roman city of Pompeii. Similarly, while Yellowstone Caldera in Yellowstone National Park last erupted at least 640,000 years ago, geologists believe that it is dormant rather than extinct.Learn More
Stacks of lava that are very thick can take years to cool down completely. Lava forms a thin crust at the top that cools in 10 to 15 minutes, but the flow underneath can take much longer to cool.Full Answer >
The Eldfell volcano is part of the Vestmannaeyjar system of underwater volcanoes in southern Iceland. Eldfell is located on Heimaey Island, one of the few inhabited Icelandic islands. This fissure-vent volcano rises 915 feet above sea level and is the highest point on Heimaey Island. As of July 2014, the last time the volcano erupted was in 1973.Full Answer >
Mount St. Helens has erupted numerous times in its 300,000-year history, most notably on May 18, 1980. While much of its early history remains a mystery, geologic studies have concluded that Mount St. Helens is the most active volcano in the Pacific Northwest.Full Answer >
Lava solidifies as it cools and ultimately turns into solid rock. The rock formed by cooling lava varies in composition.Some rocks are dense and heavy, while others have porous compositions and are lighter in color and weight.Full Answer >