Earthquake physics has undergone a revolution during the past decade, thanks to new insights from lab experiments, field studies of exhumed faults and better theories.
But the nature and behavior of the forces that keep faults from moving and then suddenly fail are still unknown. And when faults do move, something is missing—there is little to no evidence of the extremely high levels of friction and melting that would be expected to follow above ground when two giant rocks slid against each other.
Most earthquakes happen where tectonic plates meet and glide against each other. Quakes occur when the frictional stress of the movement exceeds the strength of the rocks, causing a failure at a fault line. Aggressive displacement of the Earth's crust follows, leading to a release of elastic strain energy. This energy takes the form of shock waves that radiate and constitute an earthquake.
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