We don’t often hear about earthquakes hitting the Southeastern US. Especially strong ones.

They do happen, though—as evidenced by the magnitude 5.8 quake that shook Mineral, Virginia, in 2011.

The thing is, for the longest time no one seemed to know why these disasters occasionally impact that part of the country.

Or at least that was the case until some scientists at University of North Carolina-Chapel Hill made a discovery that helps explain these shocking—and thankfully uncommon—tremblors.

Before we detail their findings and discuss what they mean for the region’s homeowners, though, let’s take a step back, define earthquakes, and talk about why the Southeast rarely experiences them.

What are Earthquakes and Why Don’t They Hit the Southeast?

Again, it’s unusual for an earthquake to shake the Southeastern US. This is because they usually occur on the edge of a tectonic plate.

Why? According to the United States Geological Survey (USGS), the earth has an inner core, outer core, mantle, and crust. The top portion of the mantle and the crust double as the earth’s surface.

As we’re all keenly aware, that surface isn’t smooth. It also isn’t composed of a single “piece” of mantle or crust. Instead, it’s made up of many pieces. We call them tectonic plates, and their edges, plate boundaries. The plate boundaries are made up of fault lines—where most quakes occur. This is because the mantle and crust move around a lot, causing the plate boundaries to shift and scrape against each other.

The Southeastern US is nestled inside the North American Tectonic Plate’s boundaries. In other words, it’s not on the plate’s edge, where faults usually occur.

So how did an earthquake happen there in 2011? To put it simply—part of the earth’s mantle is peeling off.

That’s where the UNC-Chapel Hill research comes into play. The university’s scientists believe some of the North American plate’s base is falling away. Because of this, the remaining mantle has become weaker and more prone to slipping along fault lines. Which brings us back to the quake that rattled the Southeast a few years ago.

How Was the UNC-Chapel Hill Study Conducted?

Researchers at the university conducted their study by three-dimensionally mapping the earth’s mantle. From there, they measured the seismic activity flowing through the Southeast.

According to a related press release, they found plate thickness in the region to be “fairly uneven—they saw thick areas of dense, older rock stretching downward and thin areas of less dense, younger rock.”

And the thinner the mantle, the more likely it is to slip along the fault lines and cause earthquakes. Scientists predict this could lead to more hitting the area down the road.

What Does This Mean for the Region’s Homeowners?

Despite the possibility of an earthquake happening again in this region, it may or may not happen in our lifetime. Still, it doesn’t hurt to be prepared.

Speaking of which, here’s how you can prepare your home for a quake.

Start by making sure your home is structurally sound and up to code. After that, you may want to have your house mounted to the foundation.

Two other things you can do are secure your furnace and water heater, and ensure all walls and masonry are enforced.

By taking these precautions, your house will be more likely to withstand a medium-sized quake.

Keep in mind that standard homeowners insurance doesn’t cover earthquake damage. If that bothers you, get earthquake insurance.

Should I Buy Earthquake Insurance?

The upside of this kind of coverage is it protects your home and belongings from earthquake damage. The downside is it can be quite pricy.

If you’re deciding whether or not to purchase a policy, here are a few points to consider:

  • Your Location--Just as your location greatly affects your homeowners rates, it also affects your earthquake premiums. Unfortunately, areas more prone to earthquakes will have higher rates. But because the Southeastern US hasn’t experienced many, you may be able to find a cheap deal. Contact your insurer for further information.
  • Exclusions--What many people don’t realize is earthquake insurance only covers damage from the quake itself. Other perils resulting from it—like fires, landslides, or floods—are either covered by your standard policy or by purchasing an endorsement to it.
  • Deductibles and Premiums--Earthquake insurance is made up of both deductibles and premiums. A deductible is what you pay out of pocket before your coverage kicks in. And earthquake deductibles are known to be pricey.

Specifically, they’re often 10 to 20 percent of your coverage limit. So, say your deductible is 20 percent, your coverage limit is $500,000, and your home sustains $300,000 in damage. You’d likely pay $100,000 or more on the deductible.

Premiums are what you pay every month toward your policy. And they can be pricey as well when it comes to earthquake coverage. Insurance underwriters consider many components when determining premiums. They may look at whether you live in an earthquake-prone area and if your house has been retrofitted. They also might look at your home’s replacement cost or actual cash value.

For more information on this kind of coverage, check out our article on Earthquake Insurance Basics.