Modern-Day Earthquakes in the USA Could Be Aftershocks From Major Quakes in 1800s [Study]

The United States has encountered several tremors recently. A new report suggests that the tremors could be aftershocks from major quakes over a decade ago.

U.S. Modern-Day Earthquakes Just Aftershocks?

Researchers from Wuhan University and the University of Missouri discovered in a new study that several tremors the country experienced were linked to previous major quakes that occurred in the 1800s.

Some of the biggest earthquakes ever recorded in American history occurred during the said period, and many experts think that the recent earthquakes are simply aftershocks from those significant quakes. On the other hand, some believe they might be background seismic activity or foreshocks leading up to a bigger future earthquake.

The team concentrates its research on three significant earthquake events in North American history - the quake that struck near southeast Quebec in 1663; the three quakes that crashed near the Missouri-Kentucky border in 1811 and 1812; and the quake that struck Charleston, South Carolina, in 1886. They then examined the statistics from the U.S. Geological Survey and compared the data to contemporary earthquakes in comparable regions.

"We wanted to view this from another angle using a statistical method," Yuxuan Chen, a geoscientist at Wuhan University and lead author of the study.

The expert noted that the goal is to use the timing, distance, and magnitude of event pairings to identify the connection between two events. One earthquake is most likely the aftershock of the other if the distance between two earthquakes is closer than expected from background events.

"To come up with a hazard assessment for the future, we really need to understand what happened 150 or 200 years ago," Susan Hough, a geophysicist at the U.S. Geological Survey who was not involved in the study, said in a statement. She added that using modern methods to address the issue is critical.

Determining the nature of these earthquakes will be crucial to comprehending the potential for future disasters in different U.S. states and better understanding the geological foundations of this seismic activity.

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Earthquakes in the United States

The strongest earthquake to strike the country occurred in the early 1800s along the New Madrid fault near St. Louis, Missouri. It destroyed buildings in Charleston, South Carolina, in the late 1800s.

At least a thousand small earthquakes annually occur in the Eastern Tennessee Seismic Zone. All the earthquakes on the map of the eastern United States are examples of intraplate earthquakes, defined as earthquakes that occur in the center of tectonic plates.

According to The United States Earthquake Report, several states were hit by an earthquake on Tuesday. A 2.2-magnitude tremor hit San Jose and Salinas in California, and a 2.8-magnitude tremor also struck Anchorage, Alaska, and Oklahoma City.

Earthquakes of magnitude 2.5 or less are usually not felt but detected by seismograph. Tremors between 2.5 to 5.4 magnitude are often felt and cause minor damage. When the magnitude reaches 6.1 to 6.9, it may cause a lot of damage, especially in populated areas. Quake magnitudes between 7.0 and 7.9 are considered a major earthquake with serious damage, and when it is stronger than that, it is considered a great earthquake, and it can ruin the communities near the epicenter.