Chapter 8 Earthquakes

Recent Earthquakes Kobe Earthquake Kobe Earthquake Satellite Photos - Japan Before and After Tsunami - Interactive Feature - NYTimes.comSatellite Photos - Japan Before and After Tsunami - Interactive Feature - NYTimes.comSatellite Photos - Japan Before and After Tsunami - Interactive Feature - NYTimes.comSatellite Photos - Japan Before and After Tsunami - Interactive Feature - NYTimes.com Video of Tsunami - Video Library - The New York TimesVideo of Tsunami - Video Library - The New York TimesVideo of Tsunami - Video Library - The New York TimesVideo of Tsunami - Video Library - The New York Times Earthquake and Tsunami - Video Library - The New York TimesEarthquake and Tsunami - Video Library - The New York TimesEarthquake and Tsunami - Video Library - The New York TimesEarthquake and Tsunami - Video Library - The New York Times Day 2: Japan's Earthquake - Video Library - The New York TimesDay 2: Japan's Earthquake - Video Library - The New York TimesDay 2: Japan's Earthquake - Video Library - The New York TimesDay 2: Japan's Earthquake - Video Library - The New York Times Day 3: Japan’s Nuclear Woes - Video Library - The New York TimesDay 3: Japan’s Nuclear Woes - Video Library - The New York TimesDay 3: Japan’s Nuclear Woes - Video Library - The New York TimesDay 3: Japan’s Nuclear Woes - Video Library - The New York Times Widespread Devastation in Japan - Video Library - The New York TimesWidespread Devastation in Japan - Video Library - The New York TimesWidespread Devastation in Japan - Video Library - The New York TimesWidespread Devastation in Japan - Video Library - The New York Times

Where do earthquakes occur? On Earth of course Seismology is the study of earthquakes Most quakes occur at the edge of tectonic plates Tectonic plates are pieces of the lithosphere that move on top of the asthenosphere

Plate tectonics Plates push and pull upon one anotherPlates push and pull upon one another Faults occur when the crust breaksFaults occur when the crust breaks Breaks occur at the edge of plate boundariesBreaks occur at the edge of plate boundaries

What causes Quakes The changing of rocks due to stress is called deformation Focus is the area in the crust where the rock under stress breaks Epicenter is the point on Earth’s surface directly above the focus

Focus and epicenter

Earthquake Characteristics Plate Boundary Fault type Stress force TransformStrike-slipShearing ConvergentReverseCompression DivergentNormalTension

E-quake Motion Seismic WavesSeismic Waves –Waves of energy that travel through the earth Seismic waves classified as:Seismic waves classified as: –P waves –S waves –Surface

P and S waves Travel through the EarthTravel through the Earth Released from FocusReleased from Focus When they reach the surface at epicenter become Surface wavesWhen they reach the surface at epicenter become Surface waves

P and S Wave Characteristics P wavesP waves Primary wavePrimary wave Pressure wavePressure wave Arrives firstArrives first Travels through solid, liquid or gasTravels through solid, liquid or gas 1 st wave to be detected1 st wave to be detected S waves Secondary wave Shear wave Arrives last Cannot travel through liquid

Surface wave Move the ground up and down in circlesMove the ground up and down in circles Travel slower than P and S but are more destructiveTravel slower than P and S but are more destructive

Measuring E-quakes Common MethodsCommon Methods –Mercalli Rating based upon damageRating based upon damage –Richter Rating based upon seismic waveRating based upon seismic wave –Moment Magnitude Rating based upon total energy releasedRating based upon total energy released Used to rate all earthquakesUsed to rate all earthquakes

Earthquake Damage Damage occurs due to:Damage occurs due to: –Shaking –Liquefaction Loose soil turns to mudLoose soil turns to mud –Aftershocks Earthquake after larger earthquakeEarthquake after larger earthquake –Tsunamis Water displacementWater displacement