Earth Movements
Earth Movements : (1) Rotational 23.5*; top like. (2) Revolve around the sun. (3) "Elasticrebound" theory by Reid: Earthquakes occur in regions subject to deformation due to external causes, generally regional tectonic stresses. When the accumulated strain at some point exceeds the strength of the rock there is brittle fractures at competent rock and/or slip on pre-existing zones of weakness