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Unformatted text preview: is far away Surface waves dissipate in 2 directions. And energy spreads as 1/r Body waves spread as spherical wave fronts through the earth (3D) so energy spreads as 1/r^3 (graph) Focal mechanisms: -if first motion is upward to or to the seismograph, it is positive and showed by bubbled in.-if first motion is downwards away or away from the seismograph, it is negative....
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- Fall '07