[ad_1]
Earthquakes are rare but almost unheard of in North Carolina, a state far from the active tectonic plate boundary that produces most of the world’s seismic activity.
However, a recent series of earthquakes in a small town near the Appalachian Mountains surprised and amazed scientists, who said they were revealing an ancient fault line that had become active again.
Recently, eight earthquakes in four weeks rocked West Canton, a town of about 1,200 people in Haywood County.
Seismic cluster: a rare phenomenon
(Photo: THIBAUD MORITZ/AFP via Getty Images)
The first earthquake in the series occurred on May 23, 2023, at 9:46 PM local time.
It had a magnitude of 2.8, and was centered about 2.5 miles northwest of Canton, at a depth of 3.1 miles, according to Phys.org.
Six more earthquakes followed over the next three weeks, ranging in magnitude from 1.8 to 3.2, all within a few miles of the first quake.
The last earthquake occurred on June 16, 2023 at 7:32 AM local time. It had a magnitude of 2.1, and was centered about 2.4 miles northwest of Canton, at a depth of 3.7 miles.
Only one person felt it in the Clyde, a town about 8 miles away.
According to the United States Geological Survey (USGS), this series of earthquakes is known as a cluster, which is defined as “a group of earthquakes that occur close to each other in space and time without a clear sequence of aftershocks.”
Clusters differ from swarms, which are “a series of many earthquakes striking in a relatively short period of time within an area several miles wide”.
Clusters are rare but not unheard of in North Carolina.
The USGS said the state has seen at least three other clusters since 1975, all in the western part of the state near the Blue Ridge Mountains.
The largest cluster occurred in December 1986 near Sparta, where nine earthquakes ranging in magnitude from 2.6 to 4.5 occurred over a two-week period.
Clusters are also rare but not unprecedented in other parts of the eastern US, where earthquakes are less frequent and smaller than in the western US. The USGS says some examples of clusters in the eastern US include:
A group of six earthquakes ranging in magnitude from 3.0 to 4.6 magnitude near Mineral, Virginia, in August and September 2011, following the main magnitude 5.8 earthquake that caused widespread damage and was felt by millions of people. A group of seven earthquakes ranging in magnitude from 2.0 to 3.9 near Youngstown, Ohio, between December 2011 and March 2012, that have been linked to the injection of wastewater from hydraulic fracturing operations. A group of five earthquakes ranging in magnitude from 2.6 to 4.0 near Irving Dallas, Texas, between January and February 2015, which have also been linked to the injection of wastewater from hydraulic fracturing operations.
Also read: 6.3-magnitude earthquake in the Philippines: no injuries, significant damage reported
The old mistake: hidden danger
A group of earthquakes near West Canton has revealed an ancient fault line running through the area, according to the USGS.
A fault is a fracture or an area of fractures in the earth’s crust along which rocks move relative to each other.
The USGS said the fault near West Canton is part of an ancient system of faults that formed hundreds of millions of years ago when the Appalachian Mountains formed as a result of the collision of tectonic plates.
These faults have been inactive for a long time, but they can become active again sometimes when pressure builds up in places where the rocks are weak.
It is not clear what caused the recent activation of the fault near West Canton, but it could be related to natural changes in the stress field or human activities such as mining or groundwater withdrawals.
Furthermore, the USGS said it’s also not clear how long the block will last or if it will lead to larger or more frequent earthquakes in the future.
However, she says there is no evidence that clusters increase or decrease the likelihood of larger earthquakes on nearby faults.
Currently, the USGS is closely monitoring the block and providing updates on its website and social media platforms.
Related article: Magnitude 6.0 Earthquake Jolts Masbate, Philippines; Serious damage and injuries were not reported
© 2023 NatureWorldNews.com All rights reserved. Do not reproduce without permission.
|
Sources 2/ https://www.natureworldnews.com/articles/57019/20230620/two-earthquakes-shake-old-north-carolina-town-within-weeks-fault.htm The mention sources can contact us to remove/changing this article |
[ad_2]