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Lecture 19 Earthquakes Lecture Outline I II A) B) C) III IV A) B) V Definitions Properties Focus and Epicenter Seismic Waves i. ii. Body Waves Surface Waves i. ii. Intensity Magnitude Strength Effects Plate Tectonics and Earthquakes Plate Boundaries i. ii. iii. Divergent Convergent Transform Subduction Angle Conclusions Lecture 19 i Definitions earthquake - the vibration felt when energy is released abruptly by the sudden displacement of rock along faults within the Earth's crust fault - fracture or fracture zone along which there has been displacement of the sides relative to one another fault line - the intersection of a fault with the surface of the Earth, or the trace of a fault on a surface of reference Tectonic Deformation Elastic Rebound Tectonic Deformation Elastic Rebound Properties Focus Epicenter Seismic Waves Stength Seismic Waves Body Waves P (primary) Waves S (secondary) Waves Surface Waves Love Waves Rayleigh Waves Seismic Waves Body Waves P (Primary)Waves S (Secondary)Waves Seismic Waves Body Waves - Refraction Seismic Waves Body Waves - Pathways Seismic Waves Surface Waves Rayleigh Waves Love Waves Detecting Seismic Waves Detecting Seismic Waves Detecting Seismic Waves Detecting Seismic Waves Detecting Seismic Waves Finding Epicenter Detecting Seismic Waves Detecting Seismic Waves First Motion Analysis Detecting Seismic Waves First Motion Analysis - Strike Slip Faults Seismic Strength Mercalli Intensity Scale Richter Scale (Magnitude) Moment Magnitude Seismic Strength Intensity Measure of severity of ground shaking Decreases with distance from focus Shallow focus (<30km) > deep focus (>100km) Greater on unconsolidated sediment than on bedrock Seismic Strength Modified Mercalli Intensity Scale 1811 New Madrid Earthquake 1906 San Francisco Earthquake Seismic Strength Richter Magnitude Scale Seismic Strength Richter Magnitude Scale Seismic Strength Moment Magnitude Effects Ground Motion Fire Landslides Liquefaction Permanent Displacement of Land Surface Tsunami Earthquake Damage Kobe, 1995 Loa Prieta, 1989 San Fernando, 1971 Taiwan, 1999 Nigata, 1964 Gujarat, 2001 Earthquake Damage Ground Motion and Rock Type Earthquake Damage Ground Motion and Rock Type Mexico City, 1985 Landslides Guatemala, 1974 Alaska, 1964 Liquefaction Collapse of beach road Liquefaction 1989 -Loma Prieta quake Sand blow at Oakland International Airport Tsunamis caused by: • earthquakes • undersea landslides • icebergs falling from glaciers • undersea volcanic eruptions • asteroid impacts Tsunamis Tsunamis Tsunamis Detecting Tsunamis Deep Ocean Assessment and Reporting of Tsunamis (DAR Tsunami Danger Atlantic Coast of North America Plate Tectonics Tectonic Setting of Earthquakes Tectonic Setting of Earthquakes Benioff Zone Earthquake Prediction Earthquake Prediction Earthquake Prediction Earthquake Prediction Earthquake Prediction Seismic Gaps
