Lowcountry Hazards Center Director Erin Beutel answers frequently asked questions concerning earthquakes and Tsunamis:
Q: Does this earthquake indicate that things are getting more active?
A: No, this is part of normal earthquake activity for the Earth. Earthquakes of this magnitude are uncommon, but not unexpected.
Q: Can we expect an earthquake of this size in South Carolina?
A: The Summerville/Charleston1886 earthquake was between a magnitude 6.9 and 7.3 (estimated based on shaking reports) and caused considerable damage, but there is currently no indication that Charleston has had earthquakes of this size at any time in its past. The Japanese earthquake is also very different from the Charleston earthquake because it occurred at a plate boundary where the motion along faults is much greater than in the middle of a plate where Charleston is located (the more motion, the more energy you can build up if it gets stuck).
Q: Are we at risk of a tsunami in South Carolina?
A: Pacific ocean tsunamis do not affect the Atlantic ocean, since most of the major tsunamigenic earthquakes occur in the Pacific and Indian oceans we are at a lower risk of a tsunami that the Pacific coastlines, but we do still have a slight risk. There is no evidence that any of the active faults (faults that have seismic activity on them) in the South Carolina area would create tsunamis. Most of the active faults in South Carolina, including the Summerville/Charleston fault are on land, and therefore could not create a tsunami. The South Carolina offshore faults are strike-slip faults, they slide side to side, not up and down (tsunamis are generated by the vertical motion, not side to side). However, there are areas of the Atlantic ocean, along the margin of the Caribbean and near Southern Spain, that are prone to thrust faulting earthquakes (these are where the two sides of the fault thrust on top of each other and create vertical displacement in the water column and a tsunami). Tsunamis may also be generated by large underwater landslides. So, South Carolinians need to be aware of the risk of tsunamis but we will likely also have some warning prior to any tsunami striking our shore.
Q: Will Japan continue to have earthquakes?
A: Yes, the area around where the major earthquake occurred will continue to experience strong shaking for many months. Current aftershocks are large enough that we would have considered them strong earthquakes in their own right (magnitudes in the 7’s and 6’s). The recent Christchurch earthquake is a good example of a large magnitude aftershock causing significant damage, the original New Zealand earthquake occurred in September and was a magnitude 7.1 with moderate damage and no deaths, while the aftershock was a 6.3 and caused hundreds of deaths.
