Earthquake

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  • Topic: Earthquake, Love wave, Seismic wave
  • Pages : 3 (435 words )
  • Download(s) : 272
  • Published : May 15, 2013
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EARTHQUAKES

o Plates sliding pass each other create friction
o Friction builds up creating stress (a force)
o Force is greater than plate can withstand, budges and breaks, creating earthquakes o Release a lot of energy

KEY TERMS
Seismology- the study of earthquakes and their effects
Seismometer/ Seismograph - equipment measuring the amount of ground motion caused by an earthquake ***Let’s do a demo***
Seismogram- record of ground motion produced by seismometer
-shows arrival time of the different types of seismic waves Magnitude- measure of the amount of ground shaking caused by an earthquake e.g. Richter Scale measures magnitude Focus- where earthquake originates inside Earth

Epicentre- location on the surface of Earth directly above the focus

SEISMIC WAVES: 2 types
o Body waves (P-wave & S wave)
o Travel in a curved direction through Earth
o Can be bounced off and refracted when travelling through different layer

1. Primary wave (P)
• Compressional wave
• Cause the ground to alternately compress and stretch in the direction they travel in • Travel at ~6km/second
• Can move through any materials-solid & liquid

2. Secondary wave (S)
• Shear wave perpendicular to the direction of wave motion • Cause the ground to squeeze and stretch at right angles • Travels at 3.5 km/ second
• Can only move through solid
• Cause more damage than P-wave because buildings in many parts of the world is NOT designed to withstand twisting

Body waves can bounce off, speed up or slow down, or refract (bend) in different layers of the Earth.

o Surface wave (Love wave)
• Travels on surface of the Earth only
• Ground motion is a rolling action...
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