Norfolk is only a few feet above sea level.
Why not consider Category 5 storms hitting Norfolk/Virginia Beach? Hurricanes are fueled by warm water, so a Category 5 storm could hit Florida or the Gulf Coast. However, hurricanes lose energy as they move north and encounter colder wate. Even with the Gulf Stream, there is no expectation of a Category 5 storm reaching Virginia.
There are three significant threats to the city that the insurance companies and banks (as well as government agencies) have to consider:
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Hurricane: If a hurricane brings a storm surge of 6-8 feet into the region, much of Virginia Beach and Norfolk will be underwater due to the storm surege, the rise in sea level associated with the lower barometric pressure in the eye of the hurricane. Local officials in this region tracks hurricanes as closely as the officials in Florida - but clearly Virginia has had better fortune than North Carolina at avoiding at least wind damage. Hurricane Floyd drowned the city of Franklin in 1999, but no hurricane came ashore directly in Virginia in the 1900's.
But inevitably, one is headed our way. The state has designated hurricane evacuation routes for getting people out of the Hampton Roads area. It assumes people will leave, calmly, in two phases, and requires reversing eastbound I-64 so there are 4 escape lanes headed west to the high ground at Williamsburg. Think that's likely to be the case? |
Sea Level Rise: At various times, the Atlantic Ocean has been higher and Norfolk has been underwater - that's why there are whale fossils from the Miocene period found in sand and gravel deposits on the Coastal Plain. If global warming continues and the sea level rises 6-12 inches per century, then Norfolk will be abandoned or sea walls will surround it in several hundred years. Seems like a long time - but we're just about to commemorate the 400th anniversary of Jamestown. At the 800th anniversary... Jamestown could be a barrier island, and the ruins of Norfolk could lie underneath sediments accumulating on the Continental Shelf.
The Native Americans who first settled Virginia camped on a different Atlantic Ocean coastline during their hunting and gathering expeditions. Their first campsites are probably 30-50 miles offshore now, under 30 fathoms of saltwater. Those sites are buried under recent sediments, perhaps for future excavation after underwater archeology develops new technologies. As sea level rose an average of 6-12 inches per century, the Native Americans in Virginia saw the Chesapeake Bay form until, by 3,000 years ago, the current shape of the bay had developed.
Tsunami: A tsunami is a "big wave." A very, very big wave... and Hampton Roads could be devastated by one.
The Cumbre Vieja volcano in the Canary Islands, off the coast of northwestern Africa, could collapse and create a tsunami that drowns Norfolk and other points on the eastern coastline of North America. The Mega-Tsunami: Wave of Destruction broadcast by the BBC highlighted the threat in October, 2000. The claim that a giant wave could threaten US due to a landslide all the way across the ocean sounds alarming, but the 1964 Alaskan earthquake created a killer tsunami at Crescent City, California.
Oddly enough, there is a second geologic risk that could generate a massive wave that might destroy Norfolk. The edge of the continental shelf could be unstable, due to subsea methane "gas hydrate" deposits. The gas is frozen... for now. If there was a change in water pressure, perhaps triggered by a strong hurricane or small landslide, a burst of methane could be released. The giant gas bubble would create a massive underwater landslide and displace enough Atlantic Ocean water to generate a tsunami that would wash over the Eastern Shore, Norfolk, and other coastal areas.
Would such a wave reach the base of the Blue Ridge, as shown in the movie Deep Impact? Perhaps not... but an unusual event 35 million years ago may have created such a wave.
If you are working for an insurance company that writes policies to insure buildings in Norfolk, you need to determine what level of risk the company can accept over the long term. The low-probability risks, such as hurricanes and tsunamis, are not zero-probability risks. Also, insurance regulators need to ensure insurance companies will be able to pay off the claims if a catastrophe does occur. It's in the interest of the State of Virginia to have insurance companies hedge their bets, and have only so many policies in one geographic area.
If 10% of a company's policies are in Tidewater and a "singularity" occurs (such as a hurricane) requiring the company to reimburse claimants, the odds are good that the company will be able to pay as planned. But if 60% of a company's policies are in one area, then too many eggs are in one basket and there's great risk the insurance company will go bankrupt rather than pay all potential claims. That could leave the taxpayers with the burden to finance reconstruction of public infrastructure (roads, fire stations, etc.) and, most likely, private homes/businesses.
