Outline for Earthquakes ES 1100 Fall 2016 Some questions we will explore: 1)What causes earthquakes? 2)Why do they occur where they do? 3)Why do some cause lots of damage? 4)Why do some kill so many people?
1923Tokyo, Japan7.9143,0001920Gansu, China7.8200,0001908Messina, Italy7.270,0001906San Francisco,California7.83,000Great San FranciscoEarthquake and Fire1886Charleston, SouthCarolina7.3602ndlargest earthquake ineastern United States1868Arica, Peru9.025,0009+1811-1812New Madrid, Missouri7.7, 7.7, 7.5SeveralLargest earthquake(s) ineastern United States1755Lisbon, Portugal8.770,000Tsunami1700Cascadia SubductionZone9.0unknown9+1556Shensi, China8.0830,000Highest deaths*Data from United States Geological SurveyWhat is an earthquake?•Vibration produced by the rapid release of energy caused by movement along a fault.Earthquake Terms•Earthquake- vibration produced by the rapid release of energy caused by movement along a fault.•Fault– fracture in Earth along which movement has occurred.•Focus (hypocenter)– point inside Earth at which earthquake originates.•Epicenter– point on Earth’s surface directly above the focus.•FaultScarp– face or cliff formed by displacement along a fault.•Fault Plane – the planar surface that forms the fault.•Fault Trace – the line where the fault plane intersects the land surface. Also called the fault line.The rocks along fault traces or fault lines are shattered. Due to increased physical weathering in the shattered rocks, fault lines are often low areas, where lakes form. Or in Scotland—lochs. What causes earthquakes?•As the tectonic plates move, stresses build up in rocks.•Rocks that are stressed will deform. They bend. But, like all materials there is a limit to how much they can bend.•Once the limit of their strength is exceeded, they will break.•They break along a fault.•
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