Seismic activity in South Carolina increases; ShakeOut drill coming

South Carolina shakes up! This last week, the state registered over half the average number of earthquakes it registers annually, and all have been in the same general area. There have been 11 quakes in Greenwood and Laurens counties in the last week; annually, there are up to 20 quakes in South Carolina each year. All earthquakes within the last week have occurred near and around the Lake Greenwood and Saluda Rivers. Luckily, these quakes have all been below 3 magnitude, and not many people have felt it or at least reported to the U.S. Geological Survey or the South Carolina Geological Survey.

This year, 25 quakes have been recorded in South Carolina, compared to 28 in 2023.

What is happening?

South Carolina is not near a major plate, but many faults are under the Palmetto State. Most faults are along the Midlands, where most earthquakes in South Carolina tend to occur.

Experts can't explain why seismic activity has increased in recent years, much less this past week. Some research from a paper published in Europe shows that hydro seismicity can trigger earthquakes in certain areas, although this might not necessarily be the case in the quakes this week.

The USGS site states, "The fluid injected at depth is sometimes hydraulically connected to faults. When this happens, fluid pressures increase within the fault, counteracting the frictional forces on faults. This makes earthquakes more likely to occur on them. An analog to this system is an air hockey table. When an air hockey table is off, the puck does not move readily, but when the table is on, the puck glides more easily. Raising fluid pressure within a fault is like turning on an air hockey table."

Strongest quake registered in South Carolina?

It was a magnitude 7.3 earthquake with an epicenter in Charleston that struck in 1886. It is the strongest quake on the East Coast recorded. It killed 60 people and was felt across much of the East Coast to Cuba and Bermuda.

Important to keep in mind

Most won't feel a quake below 2.5 magnitudes often goes unfelt, and any quakes below 5 magnitudes do not produce structural damage. The uptick in activity doesn't mean that there is a bigger one that could be coming soon or now. Recent activity doesn't correlate to a bigger quake happening soon, nor should we take it as this. But it does serve as a great reminder that people should revise their insurance policies.

International ShakeOut on Oct. 17!

Interestingly, this week is International ShakeOut Day, October 17. Millions worldwide will attend earthquake drills at work, school, or home at 10:17 a.m. local time.

• DROP where you are, onto your hands and knees. This position protects you from being knocked down and reduces your chances of being hit by falling or flying objects.
  
• COVER your head and neck with one arm and hand.
  
  • If a sturdy table or desk is nearby, crawl underneath for shelter.
  • If no shelter is nearby, crawl next to an interior wall.
  • Stay on your knees; bend over to protect vital organs.
• HOLD ON until the shaking stops.
  
  • Under shelter: hold on to it with one hand; be ready to move with your shelter if it shifts
  • No shelter: hold on to your head and neck with both arms and hands.