What’s up with recent earthquakes felt in Kentucky? What are the chances of more?
Scientists are investigating the cause of recent regional earthquake activity that affected Kentucky over the weekend.
A small 2.8 magnitude earthquake was recorded in Nicholasville in the early morning hours April 11. At least a dozen people told the U.S. Geological Survey they could feel the quake, which impacted the northern part of Garrard County. No damage was reported as a result of the quake.
A day earlier, a 4.1 magnitude earthquake with an epicenter 30 miles south of Knoxville, Tennessee, rattled homes in Southern Kentucky, WKYT reported.
According to University of Kentucky seismologist Seth Carpenter, the cause of the recent earthquakes isn’t yet well-understood by scientists.
“The most that we do know, for certain at this point, is what we learned from earthquakes that we recorded,” Carpenter told the Herald-Leader in an interview Wednesday.
“Those earthquakes tell us about how frequently events of a given size might reoccur… but they don’t give us, so far, a clear picture of the causes of those earthquakes,” Carpenter continued, adding it’s an active area of research.
Here’s what we can glean from the recent earthquake activity felt in Kentucky, with insights from Carpenter, who helped monitor it from the Kentucky Geological Survey at UK.
What causes an earthquake?
An earthquake is typically caused by a sudden slip along a fault, according to the U.S. Geological Survey.
The Earth’s tectonic plates — massive shelves of solid rock that float along the more fluid asthenosphere — are in constant, gradual motion. When they get stuck along their edges due to friction, stress builds up. When there’s enough stress to overcome the friction, an earthquake occurs, sending shockwaves of energy that cause shaking you might feel under your feet.
So how could an earthquake in the eastern half of Tennessee be felt in Central Kentucky? As explained by Carpenter, those shockwaves travel outward from a central point, much like a ripple of water disturbed by a thrown stone. The underground focus of an earthquake is called the hypocenter; the point on the Earth’s surface just above it is the earthquake’s epicenter.
“So, when people in Kentucky experienced the earthquake from Saturday, which happened south of Knoxville, it wasn’t directly the earthquake, but it was the waves that the earthquake produced,” Carpenter said.
Whether you could feel the quake from Central Kentucky comes down to a range of factors, Carpenter said, including where you were, if you were awake and whether you’re “in tune” with earthquake activity.
Can we expect more earthquakes in Kentucky?
Earthquakes are difficult to predict for several reasons. Asked in a follow-up email about the likelihood of further quakes as a result of this most recent activity, Carpenter explained it’s difficult to say conclusively.
“Nevertheless, it seems unlikely they suggest any increase in likelihood since none of them has been determined to be part of a sequence (i.e., multiple events that cluster in space and time),” Carpenter wrote in an email response.
The recent earthquakes in Illinois and Tennessee occurred in seismic zones, where earthquakes happen much more frequently, Carpenter noted. Additionally, the magnitudes recorded were not uncommon for those zones.
“The Garrard Co. event is a rare one, and although earthquakes are infrequent in the area, the magnitude of Sunday’s event was similar to previous earthquakes recorded there,” Carpenter wrote.
What to do when an earthquake strikes
If you find yourself indoors when shaking starts, the first thing you should do is drop, cover and hold on. That often means finding a strong desk or table to shelter under.
“It’s a good idea to go ahead and use one arm to cover your head and then get beneath a table, hopefully a strong one, and then with your whole body under the table, hang on to the table leg with your other arm,” Carpenter said. “That would keep the table from bouncing up or on top of you.”
If you don’t have a strong table or desk, you can also drop to the floor against a strong interior wall and cover your head and neck with your arms. Make sure to avoid anything that could easily fall over or shatter, such as windows. It’s not advisable to run out of a building during strong shaking.
If you are outside, stay away from buildings, and be mindful shattered glass from windows doesn’t always fall straight down. If you’re in bed and are woken up by shaking, you should stay there and cover your head with a pillow.
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