EARTHQUAKES

By: Hoil Patrick Pae

Daniel Vasquez

Julie Freed

Definitions (continued)

• Magnitude: a measure of the strength of an earthquake

• Intensity: the amount of damage caused by an earthquake.

• Tsunami: a giant ocean wave that forms after a volcanic eruption, submarine earthquake, or landslide.

Definitions (continued)

• Seismograph: instrument that records vibrations in the ground.

• Seismogram: a tracing of earthquake motions that is recorded by a seismograph.

• Seismic gap: area along a fault where relatively few earthquakes have occurred recently but where strong earthquakes are known to have occurred in the past.

Definitions (continued)• Earthquakes: a movement or trembling of the ground that is caused

by a sudden release of energy when rocks along a fault move.

• Elastic rebound: the sudden return of elastically deformed rocks to its undeformed shape

• Fault zone: a region of numerous, closely spaced faults.

Equations

• The richter scale was one way the scientists measured the strength of an earthquake.

• Magnitude=log10(amplitude)+correction factor

Anatomy of an earthquake

• Focus-Location within earth along a fault at which the first motion of an earthquake occurs

• Epicenter- Point on earth’s surface directly above an earthquakes foci.

• 90% of continental earthquakes have shallow focus.

• Earthquakes with shallow foci cause the most damage.

Body Waves• 2 main body

waves:

• P-Waves: Primary waves or compression waves

• S-Waves: Secondary waves or shear waves

Surface Waves

• Form from motion along shallow faults

• Surface wave= Slowest moving waves

• Mostly cause the greatest damage

• 2 Types:• Rayleigh Waves:

Ground moves in elliptical, rolling motion

• Love Waves: Rock moves side-to-side & perpendicular to direction wave travels.

Seismic Waves and Earth’s Interior

• 3 Main layers of earth: Crust, Mantle, and Core.

• 5 Mechanical Layers: Lithosphere, Asthenosphere, Mesosphere, Outer core, and inner core.

• Shadow zones: an area on earth’s surface where no direct seismic waves from a particular earthquake can be detected

Earthquakes and Plate Tectonics

• Earthquakes are the result of stress in lithosphere

• Convergent Oceanic Environments: Plates move toward each other and collide.

• Divergent Oceanic Environments: Plates move away from each other.

• Continental Environments: Plates converge, diverge, or move horizontally in opposite directions.

Earthquake Safety

• Before earthquake- have food, flashlight batteries and portable radio and clothes.

• During earthquake- stay in hallways and if in a car then stay somewhere safe.

• After earthquake- stay calm.

Resources

• http://www.google.com/imghp?hl=en&tab=wi

• http://www.ajdesigner.com/phpseismograph/earthquake_seismometer_richter_scale_magnitude.php

• Textbook