seismic waves are elastic waves. four types: 2 body waves

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Seismic waves are elastic waves.

Four types:

2 Body Waves. So called because they travel through the Earth. These are P & S waves.

P = primaryS = secondary or shear

2 surface waves. So called because they travel primarily on surface. These are Love waves and Rayleigh waves.

Two types of Surface Waves

Wavefronts and rays

Equations for Vp and Vs

Period, amplitude and frequency

Vp ~ 1.7 Vs

Since Vp > Vs > Vsw P waves generally arrive at a station first.

Mag 6.9 Earthquake in KamchatkaRecorded in Mount Soledad

What happen when the ray/wave hits an interface?

Snell’s Law:

€

sinθ1

V1

=sinθ2

V2

What happens to waves in the Earth?

Density increases due to pressure but so do the bulk and shear moduli.

Therefore rays bend!

P-wave SZ is between 104° and 140°.

S-wave SZ between 104 ° and 256°

P = direct PS = direct Sp = P-wave that travels up firsts = S-wave that travels up firstPP = One bounce at surface of P waveSS = One bounce at surface of S wavec = reflection from coreK = P wave through outer coreI = P wave through inner corei = P wave refected from inner coreJ = S wave through inner core

Combine:PcP = P wave that bounces off outer core and goes to surfacePcS = P wave that bounces off outer core and converts to S which Travels to the surfaceScS = S wave that bounces off outer core and goes to surfaceetc

Labeling Waves.

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