East Coast Quakes: What to Know About the Tremors Below
By Meteorologist Dominic Ramunni
7:13 PM ET Aug. 11, 2020 PUBLISHED 7:13 PM EDT Aug. 11, 2020
People across the Carolinas and Mid-Atlantic were shaken, literally, on a Sunday morning as a magnitude 5.1 earthquake struck in North Carolina on August 9, 2020.
Centered in Sparta, NC, the tremor knocked groceries off shelves and left many wondering just when the next big one could strike.
Items lie on the floor of a grocery store after an earthquake on Sunday, August 9, 2020 in North Carolina.
Fault Lines
Compared to the West Coast, there are far fewer fault lines in the East. This is why earthquakes in the East are relatively uncommon and weaker in magnitude.
That said, earthquakes still occur in the East.
According to Spectrum News Meteorologist Matthew East, “Earthquakes have occurred in every eastern U.S. state, and a majority of states have recorded damaging earthquakes. However, they are pretty rare. For instance, the Sparta earthquake Sunday was the strongest in North Carolina in over 100 years.”
While nowhere near to the extent of the West Coast, damaging earthquakes can and do affect much of the eastern half of the country.
For example, across the Tennesse River Valley lies the New Madrid Fault Line. While much smaller in size than those found farther west, the fault has managed to produce several earthquakes over magnitude 7.0 in the last couple hundred years.
In 1886, an estimated magnitude 7.0 struck Charleston, South Carolina along a previously unknown seismic zone. Nearly the entire town had to be rebuilt.
Vulnerabilities
The eastern half of the U.S. has its own set of vulnerabilities from earthquakes.
Seismic waves actually travel farther in the East as opposed to the West Coast. This is because the rocks that make up the East are tens, if not hundreds, of millions of years older than in the West.
These older rocks have had much more time to bond together with other rocks under the tremendous pressure of Earth’s crust. This allows seismic energy to transfer between rocks more efficiently during an earthquake, causing the shaking to be felt much further.
This is why, during the latest quake in North Carolina, impacts were felt not just across the state, but reports of shaking came as far as Atlanta, Georgia, nearly 300 miles away.
Reports of shaking from different earthquakes of similar magnitude.
Quakes in the East can also be more damaging to infrastructure than in the West. This is generally due to the older buildings found east. Architects in the early-to-mid 1900s simply were not accounting for earthquakes in their designs for cities along the East Coast.
When a magnitude 5.8 earthquake struck Virginia in 2011, not only were numerous historical monuments in Washington, D.C. damaged, shaking was reported up and down the East Coast with tremors even reported in Canada.
Unpredictable
There is no way to accurately predict when or where an earthquake may strike.
Some quakes will have a smaller earthquake precede the primary one. This is called a foreshock.
The problem is though, it’s difficult to say whether the foreshock is in fact a foreshock and not the primary earthquake. Only time will tell the difference.
The United State Geological Survey (USGS) is experimenting with early warning detection systems in the West Coast.
While this system cannot predict earthquakes before they occur, they can provide warning up to tens of seconds in advance that shaking is imminent. This could provide just enough time to find a secure location before the tremors begin.
Much like hurricanes, tornadoes, or snowstorms, earthquakes are a natural occuring phenomenon that we can prepare for.
The USGS provides an abundance of resources on how to best stay safe when the earth starts to quake.
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