| by Rhonda Linseman-Saunders It seems silly now, of course, but don't tell me you weren't at least a little freaked out by the possibility of a tsunami hitting the Keys after the earthquake in Haiti last Tuesday. About half an hour after the earthquake, rumors were swirling about the possibilty of a tsunami barreling its way toward South Florida. Thoughts of the devastating seismic wave in Indonesia filled the heads and fueled the imaginations of many. One local mother (okay, it was me) contemplated putting life vests on all her children and sitting on the roof to wait for the powerful, mile-high wall of water to strike. Since we seem to have a constant stream of people moving to and from Key West, I think it's safe to assume I am not the only local person who sometimes feels like an idiot about what is and is not realistic in terms of natural disaster possibilities around here. So I asked the experts at the National Weather Service in Key West. I knew they'd come through for us on short notice. I've yet to meet a weather geek who doesn't love to talk about his or her area of expertise. Thank goodness for that. Our resident tsunami expert, "Tsunami Jon" Rizzo, is the Warning Coordination Meteorologist at National Weather Service Key West. He graciously agreed to help us put the recent horrific earthquake in Haiti into perspective for the Florida Keys. For one thing, he said the earthquake was centered near the southern coast of Haiti, which meant there wasn't a strong impulse to generate a wave in the Atlantic Ocean. A local wave did travel along the south shore of the Dominican Republic, but it was only 12 centimeters in height. Pacific tsunami prediction and monitoring has been in place since 1946, but the 2004 tsunami in Indonesia and east Africa provided an opportunity to develop a better detection network on our side of the globe. Special buoys called DART buoys (for Deep-ocean Assessment and Reporting of Tsunami) transmit round-the-clock to the Pacific Tsunami Warning Center in Hawaii, which monitors and forecasts for the Caribbean Sea, and the West Coast-Alaskan Tsunami Warning Center in Palmer, Alaska, which monitors the north Atlantic and Gulf of Mexico. The mission of these Tsunami Warning Centers is quite intense. At the moment a large earthquake occurs, they have minutes to ascertain the location, depth and type of sea floor movement. If a tsunami may be generated, a computer simulation is run to predict when, where, and how high the waves will be for an entire ocean. These predictions and warnings are issued through the National Weather Service, enabling a local forecast office such as Key West to transmit the warning on NOAA Weather Radio, and activate the Emergency Alert System. The total time to accomplish this feat? Less than five minutes from the moment seismographs record the earthquake. HISTORY IN THE KEYS ACCORDING TO TSUNAMI JON: The history of tsunami is practically nonexistent in the Florida Keys. As old as the City of Key West is, it is quite young compared to the records transcribed from the lore of native cultures in the Caribbean islands, Europe, and South Pacific. But there actually is a small history of earthquakes in the Florida Keys, and a possible tsunami in the vicinity of the Florida Straits. On the night of January 22-23,1880, five separate shocks were felt in Key West. These were due to a very strong earthquakes near San Cristobal, in western Cuba. Mild aftershocks were felt in Key West through January 26th. But since that intense earthquake likely was centered over land, no tsunami was generated. We do know that the east coast of the United States has a history of tsunami. A pair of powerful earthquakes north of the Dominican Republic sent large waves toward the Carolinas and New England in August of 1946. And a small tsunami struck the northeast United States in 1964. But the history of tsunami south of Daytona Beach does not exist in recorded history. That said, a curiosity still surrounds the great earthquake that struck Lisbon, Portugal, on November 1, 1755. A large section of the Eurasian Plate, perhaps in excess of 350 miles, ruptured and jumped upward. A large tsunami swept across the Atlantic, bringing a series of waves up to 20 feet in height in the area of Antigua and the British Virgin Islands. It is likely this wave struck portions of the future United States east coast and the Canadian maritime coast. A historical study of records from the British Royal Navy hinted that a series of waves with no adverse weather reached the port at Santiago, Cuba (on the south coast), as well as Havana Harbor during November 2nd, 1755. Also, records indicated that two vessels attending a larger vessel, possibly a Spanish Galleon operating under a foreign flag, left their positions to shelter in the lee of "the Tortugas" due to high swells. There was no mention of weather of any kind--no thunderstorms and not even strong winds. It is unknown whether the larger vessel made it to its destination. While we may never know for sure, this anecdotal evidence suggests a tsunami did actually cross the entire Atlantic Ocean and reached the Florida Straits. Today, scientists at the Pacific Marine Environmental Laboratory and at several universities have been modeling tsunami. The results for the Keys? None of the many simulations ever gave a result that indicated a truly devastating tsunami. This is likely due to the broad shallow shelf west coast of Florida, and the gentle slope off Louisiana. While both make these areas vulnerable to higher hurricane storm surges, it actually works against the tsunami. It is estimated that the arrival of tsunami crossing the North Atlantic source regions would take about nine hours to reach Key Largo, and likely take an additional hour to work its way to Key West. For an earthquake north of Haiti, it would take about three hours for the wave to reach Key Largo. The maximum height would likely be on the order of 18 to 22 inches in Key Largo, and near 12 inches in Key West. Basically, this would be a hazard to our numerous marinas, and could require an incoming cruise ship to reverse course to avoid grounding on the reef. But these wave heights would not cause a flood disaster of the proportions seen in Indonesia in 2004, or even on the level of Hurricane Wilma. Feel better? Me, too. Thanks Tsunami Jon Rizzo and the team of expert weather people at National Weather Service Key West who care enough about this stuff for all of us. |