GREENSBORO, N.C. — If you heard it early this morning, chances are it scared you! We all wanted to know, “What in the world was that loud boom?” It was an earthquake!
Some described it as the sound of an explosion, thunder, or even a tree falling, but why is that?
RELATED: Shook: Small Earthquake Is All the Talk in the Triad After Many Felt a Shake or Heard the Boom
WFMY News 2’s Terran Kirksey explains why you heard it rather than felt it but it all depends on a few factors.
HOW AN EARTHQUAKE RELEASES ENERGY
When an earthquake occurs it releases energy in two main ways: shaking and noise.
WHY DID THE EARTHQUAKE SOUND LIKE AN EXPLOSION OR THUNDER?
The shallower the epicenter the more energy that can reach the surface. It’s harder for the energy to move through the Earth’s crust as shaking than it is to move through the air as noise. Because of this, in general, more people can hear an earthquake than can feel one since the noise travels farther from the epicenter than the shaking.
Conversely, the deeper an epicenter, the less likely it is for the energy to reach the surface in high enough amounts to be felt or heard easily.
EARTHQUAKE RATTLES THE TRIAD
The USGS initially reported the earthquake as a 2.2 magnitude. The intensity was revised Tuesday morning upward to 2.6.
The epicenter looks to be near the Guilford/Randolph County border. Some people felt the earthquake as far away as Raleigh and Charlotte according to a USGS map.
ARE EARTHQUAKES RARE HERE?
Are earthquakes rare here? Yes, but they can happen occasionally. Here's the historic frequency from the USGS.
On average, North Carolina typically sees a handful of earthquakes per year. Typically, they're small. In recent years, similar earthquakes to this one have been reported more commonly in the NC mountains.
