Hurricanes, tornadoes, and even winter storms. We have to deal with our share of natural disasters on the Grand Strand and in the Pee Dee. One potential natural disaster you probably didn't often think about, until 2 months ago, is earthquakes. And they pose a very real risk in South Carolina.
Two months ago, a magnitude seven earthquake struck Haiti. Haiti has a history of earthquakes, but this latest quake was the country's worst case scenario. The violent shaking killed more than 200,000 people and brought down 90 percent of buildings located near the capital Port-au-Prince.
An earthquake of that magnitude happened in South Carolina over a hundred years ago. In August of 1886, a 7.3 magnitude quake rocked Charleston, killing more than 60 people and destroying buildings across the state.
The Charleston earthquake of 1886 and the Haiti earthquake of 2010 were both devastating, but had different causes.
Haiti is located on a major boundary between the North American Plate and the Caribbean Plate. Dr. Erin Buetel, a geologist at the College of Charleston says the constant pushing of the plates against each other ultimately lead to the quake in January. "Plates are like log rafts floating around on the surface of the mantle, and where they rub up against each other is a plate boundary and so that's where we have our largest and most frequent earthquakes and haiti is on one of those boundaries."
South Carolina is located near the middle of the North American plate, with fault lines running through it. We're more than 3,000 miles away from the active boundary in the Atlantic, but it's the movement along the boundary that leads to the earthquakes we have here, says Buetel. "We are actually in the middle of one of those log rafts, but we're at a place where those logs are a little loose so there are stresses being acted on the plate and so when you push on the log raft or the plate, the places where the logs are loose have a tendancy to wiggle and that wiggle produces earthquakes."
The closest faults run through Marion, Florence and Williamsburg counties. Even though there aren't any known faults running under the Grand Strand, Buetel says traces of past quakes may have been erased. "It's all covered with layers of sand and mud and that sort of thing so we actually have a hard time knowing where the cracks are and unless and earthquake has occurred on them or the USGS has seismically imaged them we don't know where they are which is why we have a hard time predicting which areas might have an earthquake."
So while there are differences in the causes of earthquakes in Haiti and here, there are some similarities. Buetel says in either type of quake, a process known as liquefaction makes buildings and infrastructure vulnerable. Liquefaction is when the ground changes from a solid to a liquid. Living by the coast, the water is very close to the surface so any shaking from an earthquake would cause the once stable land to become more like quicksand.
Liquefaction would impact most of Horry and Georgetown counties and even parts of the Pee Dee. Alicia Bastian, a Natural Hazard Planner for Horry County Emergency Management says a major earthquake here would be like every natural disaster we've dealt with - all at once. "I think overall problem would be the overall infrastructure all together, utilities, water main breaks, the pancaking of the houses, people being stuck in voids, just like they were in haiti. So you would have a lot of trapped people. people dying, the panic. All of those would go down at once. People wouldn't know what to do. There would be no phone lines. You know the possibility of no communications or how to get help."
But while a major earthquake in our area is possible, it's more likely we'd have to deal with the impacts from another major quake in Charleston. Unlike Haiti, where the impacts stayed relatively close to the epicenter, the shaking from a quake in Charleston would travel much greater distances, just like it did in 1886. "They felt it in Cuba, and they felt it in Boston and they felt it in Milwaukee, Wisconsin so we know that's there's definitely a large area of impact," said Buetel.
Dr. Buetel compares the kind of damage we'd see here to that of a direct hit by a category one or two hurricane, but without the warning. "We'd see varying damage from disruptive roads, slight disruption of infrastructure, liquefaction features and so that causes house to go kattywampus, roads to be impassable. "
History would suggest another 7.0 in Charleston is a century away, but Beutel says it wouldn't surprise her if a six struck Charleston tomorrow.
The constantly shifting plates beneath us promise another major earthquake is in South Carolina's future, but because of our advanced infrastructure, the type of destruction seen in Haiti, is not.
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