51) Earthquakes result from the sudden release of elastic strain : 2086503
51) Earthquakes result from the sudden release of elastic strain energy previously stored in rocks surrounding a zone of fault movement.
52) The crust, mantle, and outer core are solid.
53) The mantle is composed mainly of metallic iron with small amounts of magnesium silicate minerals.
54) The Mercalli earthquake magnitude scale is based on the total amount of energy released by the earthquake.
55) Oceanic crust is mainly basaltic in composition; the mantle is more like the igneous rock peridotite in chemical composition.
56) The epicenter of an earthquake is on the surface of the Earth directly above the focus.