Ancient giant eruptions in the Pacific Northwest may actually have been caused by the tearing of a titanic slab of rock and not the supervolcano underlying Yellowstone National Park, scientists now suggest.
Supervolcanoes are capable of eruptions dwarfing anything ever recorded by humanity. There are roughly a dozen supervolcanoes on Earth today, one of which sits beneath Yellowstone National Park.
Volcanism at Yellowstone is thought to have started with the Steens-Columbia River flood basalts. A flood basalt is the result of a large volcanic eruption that covers vast areas with lava, and the Steens–Columbia River flood basalts erupted more than 55,000 cubic miles (230,000 cubic kilometers) of molten rock over approximately 2 million years, spewing out more than 1 million times the notorious Mount St. Helens eruption in 1980.
Flood basalts are thought to typically occur when the head of a giant mushroom-shaped upwelling of hot rock rising from near the Earth's core, known as a mantle plume, reaches the surface. Now researchers suggest a new way for these massive eruptions to form -- a breach in a massive slab of the Earth's crust.
http://www.huffingtonpost.com/2012/02/16/farallon-slab-ancient-eruptions-yellowstone_n_1282918.html
= new reply since forum marked as read