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" Subduction Zone      Subduction zones happen when an oceanic tectonic plate dives beneath a continental plate, as is the case beneath Japan. The friction between the two plates locks them together, forcing the upper plate to buckle upward. Eventually, the upper plate gives way, rebounding back over the lower plate violently to unleash an earthquake like Friday&amp;#039;s. The Looming Aftershocks      John Rundle, seismologist at the University of California, Davis, says already-devastated Japan is probably in line for powerful aftershocks from the 9.0 magnitude earthquake. According to Rundle, B\u00E5th&amp;#039;s Law\u2014which scientists use to predict aftershock frequency and magnitude, states that the largest aftershock should be an 8.0, followed by 10 separate magnitude 7.0 aftershocks, and then 100 6.0 magnitude aftershocks. &amp;quot;It would not be unusual to see another magnitude 8 earthquake,&amp;quot; he says, &amp;quot;and if it happens near Tokyo it would be a disaster of global proportions.&amp;quot;  How Japan Moved Eight Feet      Reports after the Japan quake said that the region nearest to the epicenter shifted eight feet during the event. How? As strain increases between two tectonic plates, the push of the bottom plate forces back the land on the upper plate farther and farther. Finally, the plates come unstuck. The release of all that pressure creates the earthquake, and it also lets the overlying land snap back to its original location. GPS satellites can track an individual point on land to see how far it shifts during a quake. Japan and the Pacific Northwest  Subduction zones can be found all around the Pacific Ocean&amp;#039;s Ring of Fire, the world&amp;#039;s most active volcanic and seismic zone that follows the edge of the Pacific plate. The danger area includes the United States: One such zone lies off the coast of the Pacific Northwest states of Washington and Oregon. As the diagram shows, it&amp;#039;s strikingly similar to Japan&amp;#039;s subduction zone, and seismologists worry about the big one striking there soon. The last one came on January 26, 1700, when an earthquake of approximately 9.0 in magnitude was recorded off the coast of Washington. "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/science/environment/a6558/the-science-behind-japan-earthquake-and-aftershocks/>