EARTH 20 Lecture 1: Geological Catastrophes Complete Set
Document Summary
Introduction: more than a million earthquakes a year, magnitude: amount of energy released. 2011 tohoku earthquake released about 600million times more energy than the atomic bomb dropped on hiroshima. The sudden slip on a fault (release of elastic energy) and the resulting ground shaking and radiated seismic energy caused by the slip. Plate boundaries: movement along faults=slip rates, measured in mm/yr or m/1000yr. Sudden rupture>> seismic waves: release of stored energy. Hypocenter (focus)- below the earth"s surface, the center and origin of earthquakes. Epicenter- at the top of earth"s crust at the surface, right above the hypocenter, named after the closes city that gets hit the hardest. Normal fault: hanging wall moves down relative to football. In a normal, or dip-slip fault, the block above the fault (the hanging wall) moves down relative to the block below the fault (the foot wall). This fault motion is caused by tension all forces and exults in extension.
