# Earthquakes Chapter 19. Focus vs. Epicenter _________– where the rock breaks and seismic waves begin; can be at deep or shallow depths _________ – point.

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Earthquakes Chapter 19

Focus vs. Epicenter _________– where the rock breaks and seismic waves begin; can be at deep or shallow depths _________ – point on the surface directly above the focus; usually what is used to locate the position of an earthquake Focus Epicenter

Seismic Waves _______ (P) Wave – fastest, able to travel through liquids, energy travels in the same direction wave is traveling ________ (S) Wave – slower, not able to travel through liquids, energy travels at right angles to direction wave is traveling ________ (L) Wave – travels along the surface, responsible for most of the quakes damage Primary Secondary Surface

The interior structure of the earth is determined by the pattern of seismic waves. The __________ is liquid so s-waves can not pass through. outer core

The difference in arrival times between p-waves and s-waves is called __________. The greater the lag time (shown here as the distance between the two curves) the _________ the distance away from the earthquake. lag time greater

To locate the epicenter of an earthquake, a minimum of ____ seismograph stations is needed. The location is where all circles _______. three intersect

Faults Vocabulary: __________ – surface along which rock layers move __________ – rock layers above the fault plane __________ – rock layers below the fault plane ________ – angle with the surface the fault plane makes going down into the ground ________ – direction along the surface the fault plane creates Fault Plane Hanging Wall Footwall Dip Strike

Faults _______ – Hanging wall moves down; formed from tensional forces _______ – Hanging wall moves up; formed from compressional forces ________ – Hanging wall and Footwall move horizontally past each other; formed from shear forces Normal Reverse Strike-Slip

Normal Fault

Reverse Fault

Strike-Slip Fault

Folds __________ – A-shaped or hump-shaped fold with older rock layers in the center; formed from compressional forces __________ – U-shaped fold with younger rock layers in the center; formed from compressional forces Anticlines and Synclines usually occur together and can be large or small scale Anticline Syncline

Anticlines and Synclines

Other Vocabulary: ____________ – instrument used to measure seismic waves __________ – difference in arrival times of p- and s- waves ___________ – rates earthquake by magnitude (amount of energy released) __________________ – rates earthquake by amount and type of damage ______________ – area of great vertical offset along strike of fault __________ – large ocean wave caused by vertical movement of ocean floor due to an earthquake seismograph lag time Richter scale modified Mercalli scale fault scarp tsunami

Earthquake Review The fastest seismic wave which can travel through liquids is a ___________. The Richter scale measures an earthquakes’ ____________. A U-shaped fold with the rock layers are _________ in the center is a(n) __________. A _________ fault is formed when the hanging wall moves up due to __________ forces. P-wave magnitude youngersyncline reverse compressional

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