Earthquakes occur most often along geologic faults, narrow zones where rock masses move in relation to one another. S lithosphere that creates seismic can range in size from those that are so weak that they cannot be felt to those violent enough to toss people around and destroy whole cities. About latest earthquakes version info clicking the list icon in the top right corner will load the earthquake list. S crust or upper mantle, usually caused by movement along a fault plane or by volcanic activity and resulting in the generation of seismic waves which can be destructive. S crust by the abrupt rupture and rebound of rocks in which elastic strain has been slowly accumulating.