Approximately 1,000 to 3,000 earthquakes occur each year in the Yellowstone area; most are not felt. The 1959 Hebgen Lake earthquake (M7.3) caused significant damage to park roads, show here near Gibbon Falls.
mantle definition. The region of the interior of the Earth between the core (on its inner surface) and the crust (on its outer). Note: The mantle is more than two thousand miles thick and accounts for more than three-quarters of the volume of the Earth.
The Plume Model. The idea is straightforward. A mantle plume is a large column of hot rock rising through the mantle. The heat from the plume causes rocks in the lower lithosphere to melt. The largest (and most persistent) mantle plumes are presumed to form where a large volume of mantle rock is heated at the core-mantle boundary, about 1,800 miles below the surface, although smaller plumes may originate elsewhere within the mantle.