Defining a Tsunami
As defined by our region's 2011 Hazard Mitigation Plan:
A tsunami is one or a series of great waves that are created by an earthquake, landslide, volcanic eruption, submarine earthquake or other undersea disturbance. From the area of disturbance, tsunami waves will travel outward in all directions. Tsunamis can originate hundreds or even thousands of miles away from coastal areas. A tsunami is not the same as a tidal wave. (page 4:105).
Much more information is available at Tsunami Safety.
Height alone doesn't tell the whole story of a tsunami. In his book Perils of a Restless Plant: Scientific Perspectives on Natural Disasters, Ernest Zebrowski, Jr. explains:
Tsunamis not only have great height when they strike shore, they also have a considerable wavelength, usually hundreds of kilometers long. A tsunami will pour in continuously for 15 to 30 minutes (and sometimes longer). Then, for the next 15 to 30 minutes, all of this water rushes back out. This is followed by the next wave crest, for a tsunami is never just a lone wave. The bodies of those who perish in a tsunami are not likely to be found, for most will be dragged out to sea. In fact, history has provided us with relatively few eye-witness accounts of the world's major tsunamis, for the simple reason that very few eyewitnesses survived (page 3).
While tsunamis are typically associated with the Pacific Rim states, they have occurred in the Eastern United States. In fact, the National Geophysical Data Center reports 40 tsunamis and tsunami-like waves have been documented in the Eastern United States since 1600 (none directly impacting Hampton Roads).
While the Mitigation Plan suggests a future tsunami is unlikely, the threat is still plausible.
A team of scientists has warned that one of the Canary Islands off the Coast of Africa is fractured and a big chunk of the island will someday crash into the ocean – causing a mammoth tsunami to race across the Atlantic and ravage the coast from Brazil to Canada (Science of Fear, Gardner, page 54).
Given the geographic location of Norfolk nestled behind Virginia Beach, the terrain offers some protection. In other words, the orientation of the Oceanview/Willoughby Spit areas would experience less than that along the immediate coast.
Be Notified of a Tsunami
First, do what schoolgirl Tilly Smith did which saved her family's life: observe the environmental conditions. There may not always be enough time for an official warning, so it is important that you understand natural warnings. If you are at the coast and feel a strong or long earthquake, see a sudden rise or fall of the ocean or hear a load roar from the ocean, a tsunami may follow. This is your only warning.
If time permits, warning would come from the U.S. Tsunami Warning Center via Weather Radio and Wireless Emergency Alerts and further relayed by Team Norfolk Emergency Operations via Norfolk Alert.
The recommended actions are to evacuate the beaches and have everyone move inland or get to the second floor of a hotel or other substantial building.