Kevin Myatt is The Roanoke Times' weather columnist.

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The tsunami in the Indian Ocean wasn't really a weather event. It was a geological event. But it does teach an important lesson about the power of ocean surge.

The surge created by an underwater earthquake, as happened in the Indian Ocean on Dec. 26, has similarities to that created by a hurricane, cyclone or typhoon, which is what those storms are know as in various sectors of the world.

In fact, the Indian Ocean has produced two horrible storms in the past 35 years that are perhaps most comparable to the tsunami catastrophe. Both targeted Bangladesh. In November 1970, a cyclone killed an estimated 300,000 to 500,000 people, mostly from an enormous storm surge carried across the low, swampy and very crowded nation.

A similar cyclone hit Bangladesh in April 1991, killing 138,000. Again, a storm surge, said to be about 20 feet, was blamed for many of the deaths.

The United States' most deadly natural disaster, also, was primarily a storm surge event. The 1900 Galveston, Texas, hurricane killed an estimated 8,000 when it pushed a 15-foot wall of water across the barrier island.

Earthquakes under the sea and fierce winds atop it can each cause sea water to mound up. To a ship at sea, this mounding is simply a rise and subsequent fall that may be scarcely noticed, but as it reaches shallower waters near land, the mounding sea translates into a large wave that crashes ashore with fury.

A sea surge produced by an earthquake or volano usually radiates out from a central point, like ripples on a pond. A hurricane's surge affects a much narrower area, usually about 50 miles or less on one side of the eye, where winds have consistently blown in the same direction.

So that's why a hurricane's surge may take out an island or inundate a small, low-lying nation, but a tsunami can wreak havoc in more than a dozen countries. Thinking about either makes one appreciate living in the mountains.

Gaston gets promoted

You may have heard that there were four hurricanes that made landfall in the United States in 2004. Well, officially, there are now five.

Gaston, the strong tropical storm that made landfall in South Carolina, then moved north and dumped huge amounts of rain on Richmond, has been posthumously upgraded by the National Hurricane Center to a hurricane. Its winds at landfall registered 75 mph, according to the NHC, qualifying it as a hurricane. At the time of its actual landfall, it was said to have 70 mph winds.

Upgrading after the fact isn't that unusual. When observation and data is digested after a storm has hit, meteorologists may well find the storm gained an extra boost of energy just before landfall, or that its winds were a little stronger than had been estimated or expected at the time.

Last year, very similarly, Tropical Storm Erika was upgraded to a hurricane weeks after it struck south Texas. Hurricane Andrew was upgraded from Category 4 to Category 5 almost a decade after its horrible swath through Florida.

It's an academic point, really, as the difference in 70-mph winds of a strong tropical storm and 75-mph winds in a minimal hurricane is negligible. So is the difference in a 145-mph Category 4 hurricane and a 155-mph Category 5 storm.

It's sort of like arguing whether a tornado or straight-line winds destroyed a home. Either way, it's gone.