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 mantle is the layer located directly under the sima. It is the largest layer of the Earth, 1800 miles thick. The mantle is composed of very hot, dense rock. This layer of rock even flows like asphalt under a heavy weight. This flow is due to great temperature differences from the bottom to the top of the mantle.