Tsunamis
Defining a Tsunami
As defined by NOAA:
A tsunami is one of the most powerful and destructive natural forces. It is a series of extremely long waves (multiple waves tens-to-hundreds of miles between crests) caused by a large and sudden displacement of the ocean. Tsunamis radiate outward in all directions from the point of origin and can move across entire ocean basins. When they reach the coast, they can cause dangerous coastal flooding and powerful currents that can last for several hours or days.
Wavelength
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 the 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 eyewitness accounts of the world's major tsunamis, for the simple reason that very few eyewitnesses survived
(page 3).
U.S. Impact
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 that 40 tsunamis and tsunami-like waves have been documented in the Eastern United States since 1600 (none directly impacting Hampton Roads).
Probability
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 when a tsunami struck Thailand in 2004: observe the environmental conditions. Tilly noticed water seemed to be rolling farther up the beach than it had a few minutes ago and warned her parents a Tsunami might be coming.
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 loud roar from the ocean, a tsunami may follow. This may be your only warning!
If time permits, a warning or alert would come from the U.S. Tsunami Warning Center via Weather Radio, Wireless Emergency Alerts, and the Emergency Alert System. Additional information would then be relayed by Team Norfolk Emergency Operations via Norfolk Alert.
Tsunami Safety
If a tsunami threatens, 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.
