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Objectives 1. Compare the 3 types of seismic waves. 2. Discuss the method scientists use to pinpoint an Earthquake (EQ). 3. Discuss the method most commonly used to measure the magnitude of EQs. 3 major Types of Seismic Waves. Move fastest. P waves : primary wave. ____________________
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Objectives 1. Compare the 3 types of seismic waves. 2. Discuss the method scientists use to pinpoint an Earthquake (EQ). 3. Discuss the method most commonly used to measure the magnitude of EQs.
3 major Types of Seismic Waves Move fastest • P waves:primary wave. • ____________________ • 1st to be recorded • Travels through _________ & ________ • More rigid material. = _____________ Liquids Solids Faster
3 major Types of Seismic Waves • S waves:secondary waves. • 2nd waves to be recorded • Only travel trough __________________ Solids
3 major Types of Seismic Waves Long • L waves:surface waves, also called ____________ waves. • Converted from P & S waves when they reach they ____________________ • Slowest-moving waves • __________________ to be recorded • Cause surface to rise & fall Reach the surface Last
Comparing Seismic Waves 2nd 1st slowest 1.7 rigid ocean right waves damage
Recording EQs instrument used to detect and record seismic waves • Seismograph: _________________ _____________________________. • Determines the ____________and not the _________________ of the epicenter. distance direction
Locating an EQ Distance-Determined by seismograph- scientists analyze the ____________ between the arrival times of the ____ and the _____ waves. Locating the epicenter-At least 3 seismograph is needed to locate the epicenter. The method is called _____________. difference P S Triangulation
Two recording N.S and E.W vibrations One recording vertical vibrations
Locating an EQ • Scientists compare time diff. btwn P & S waves. • Plot on graph to get distance to ____________ Epicenter
Triangulation EX: 3 seismographs at locations A, B, and C, determined the distance of each point from the epicenter. Point A (seismograph 1)is 500 km, point B (seismograph 2) is 800 km and point C is 1200 km (seismograph 3) away from the epicenter. Locate the epicenter.
Locating an EQ 3 • Need ____ plots to locate epicenter • Point where all 3 circles meet is location of __________________ Epicenter
EQ Scales magnitude intensity 31.7 I-XII 9.5 Little damage X 7 6-7 2.5-6 total destruction Microquakes
EARTHQUAKE DAMAGE • Movement of the ____________ itself seldom causes many deaths or injuries. • Most injuries result from the collapse of the buildings, ___________________ and falling objects. ground Flying glass
Damages Flood Fire Landslide • Most buildings are not designed to withstand the swaying motion caused by ______________________. • Buildings may collapse, sway violently, or tip over to the neighboring structure. • Tall buildings should be built on soil or rock that is firm. Loose soil and rock can vibrate like jelly. earthquakes
Tsunami (harbor wave) _____________ and under water ______________ can cause tsunamis. Tsunamis can cause massive death and damages. Faulting landslides
SSWWS: Seismic Sea Wave Warning System: Seismic network around the Pacific Ocean.Allows scientists to estimate the arrival times of the _________________ at different locations. tsunamis