Tsunami/Earthquake Events
(Source: Natural Hazards Mapserver, NOAA - National Geophysical Data Center)
The tide on the Virginia coast rises and falls about three feet, twice a day, at the NOAA reference stations. In theory, a tsunami (formerly called a "tidal wave") could create a sudden surge as much as 10-25 feet to Virginia's eastern coastline. Very few earthquakes occur near the "passive margin" of Virginia, and very few tsunamis occur in the Atlantic Ocean and reach the Virginia coast. The risk of Virginia being affected was considered very low - until recently.
Norfolk became the first "Tsunami Ready" city in Virginia in January 2006, after the disastrous tsunami in the Indian Ocean in December, 2004 raised consciousness. As Willoughby Spit in Norfolk is developed, the risk to Norfolk could grow significantly. The assistant director of emergency preparedness and response thought that he would win the lottery before a tsunami affected Hampton Roads, but said “I went after it because of the potential there would be some federal funds available.”1
Now, however, a scientific study of cracks at the edge of the coastal shelf suggests a higher risk. An earthquake at the Puerto Rico Trench could trigger an underwater landslide, 80 miles offshore and 300-600 feet underwater, and spawn a tsunami that would strike the Virginia coastline. Another possibility is that methane hydrates, now buried as ice in coastal shelf sediments underneath the Atlantic Ocean, could warm up quickly. If the methane shifted from ice to gas, the gas would "bubble up" to the surface and create a wave that could swamp the Virginia shoreline. A third risk is that the Cumbre Vieja volcano in the Canary Islands could collapse, triggering a tsunami hours later on the Virginia coast.
Tsunamis have already struck north and south of Norfolk, on the western edge of the Atlantic Ocean. Port Royal in Jamaica was hit by tsunamis after the 1692 earthquake. The Palisadoes sandspit sank, killing one-third of the residents. Newfoundland was affected by a tsunami in 1929.
About 35 million years ago, a comet or meteorite strike near Hampton Roads may have sent waves to the foothills of the Blue Ridge. If that happened again, the impact on Norfolk and Virginia Beach - and even Richmond - would be catastrophic. An asteroid impact in the Atlantic Ocean could leave Washington, DC as an island surrounded by salt water.
In the movie Deep Impact, a comet slammed into the Atlantic Ocean and the waves washed up to the base of the Blue Ridge. The scene at the end of the movie of a traffic jamgetting swamped by waves was filed on the 234 bypass in Prince William County - but don't look in Fauquier County for those pine forests into which the main characters escaped. Those ponderosa pines are located in the western United States, so the movie's final scenes were not filmed in Virginia.