GEO 303 Lecture Notes - Lecture 13: Seismic Wave, Seismogram, Seismometer
14 Nov 2016
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Document Summary
Seismic waves continue/review: p waves: primary push-pull (compressional), travel fastest, arrive at distant point first, s waves: secondary, shear motion, do not travel through liquid, arrive second, surface l waves: travel around earth. The time at which a seismometer receives the signal from the earthquake helps determine how far away the earthquake is. To calculate how far away the earthquake is, you have to know the relative arrival times of the p and s waves- depends on distance of seismometer from earthquake. Probing the deep interior: wave velocities and ray paths depend on properties of materials, waves bounce off (reflect) or bend (refract) at layer interfaces, seismic discontinuities: changes in velocity occur at compositional physical boundaries. Changes in velocity associated with changes in composition; abrupt change in direction of waves: seismic wave reflection and refraction. As wave hits a boundary with different material it will refract or bend- amount depends on differences in velocity.
