This video from a Princeton project known as Global ShakeMovie illustrates the up-and-down velocity of the magnitude 5.9 earthquake that shook eastern regions of the country, radiating from Virginia, on Aug. 23. Strong blue waves indicate rapid downward surface movement, while strong red waves indicate strong upward motion./nPrinceton seismologist and Professor of Geosciences Jeroen Tromp explained that earthquakes of this magnitude are unusual on the U.S. East Coast because, unlike the West Coast, the region is not a border between tectonic plates. Earthquakes in the eastern United States instead occur in a single plate's interior. However, the fact that the Virginia earthquake was felt over a large area is normal for the East Coast, where the ground absorbs very little of the vibration. Given the population density of the East Coast, Tromp said, these shallow earthquakes -- even a 5.9 magnitude earthquake, which is considered "moderate" -- can be intense and dangerous./nResearchers at Princeton investigate and inform the public about earthquakes worldwide through Global ShakeMovie, an online portal that shows near-real-time visualizations of recent earthquakes worldwide. These visualizations, which are usually live within seven hours of an event, are based on simulations carried out on a large computer cluster in order to provide information that enhances the public's knowledge and understanding of earthquakes./nFor more information about Global ShakeMovie and videos of other recent earthquakes, visit ‪http://global.shakemovie.princeton.edu‬

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