From Teachable Moment ( http://www.iris.edu/hq/retm ) Magnitude 7.8 Earthquake in Northern Sumatra on April 6, 2010. The paths of seismic waves from an earthquake are recorded by UPOR seismic station in Portland Or 13,408 km (8,331 mi) from the epicenter. This is 120.8° away which is in a zone between 104° and 140° of angular distance away from an earthquake where P waves are refracted away from their path, thus don't reach UPOR. Watch animation, "1.ShadowZones_640_med.mov for information.
More animations are found on:
http://www.iris.edu/hq/programs/education_and_outreach/animations
and
http://www.iris.edu/hq/programs/education_and_outreach/animations/teachable
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