At around 10:16 a.m. Thursday morning, a magnitude 5.0 earthquake was registered in Texas, near the area of Mentone, Texas, about 50 miles southeast of Carlsbad. Seismic instruments indicate the earthquake originated at a depth of around 5.3 miles.
“The preliminary (reading) was 4.7, then they reviewed it, and it came out at 5.0,” Dr. David Wilson, scientist in charge at the United States Geological Survey (USGS) Albuquerque Seismological Labs said.
In the last four days, at least five other smaller quakes have been recorded in the sparsely populated southern New Mexico and west Texas areas, the USGS reported.
And, while most might think COVID-19 doesn’t have a reach into something as remote as an earthquake, travel shutdowns and social distancing, even in remote areas, like the epicenter of the quake, have had an effect.
“I was starting to actually put a seismic network down in your area until a few weeks ago,” USGS research geophysicist Justin Rubinstein, who is working with the Bureau of Land Management and the State Land Office for permitting to put more seismic stations in the area, said. “The plan is to keep going. As you might guess, things have slowed down. But, fortunately we do have two stations in the area, and they did record the activity.”
Perceived shaking of the quake was strong, generating more than 1000 questions to the USGS, and was felt widely in Lea County from the Hobbs area south. But, the intensity changes with distance from the epicenter of a quake.
“Of course, it depends on how close you are (to the epicenter),” Wilson said. “If you were very close to it, you would experience strong shaking with a magnitude five.”
And, Hobbs, and points south, are definitely within the range to feel the quake, Wilson said.
“For that sort of distance the intensity, they call it the Modified Mercalli Intensity (MMI) Scale, which is a listing of intensities, Hobbs would have been in the intensity three sort of range,” Wilson said. “It goes up to nine, but it looks like the epicenter was in the five or six range.”
An MMI of around three would “felt by several; vibration like passing of a truck.”
“In (the Hobbs area) it would be felt, but not particularly strong,” Rubinstein said. “When you’re closer to the earthquake, that will make the shaking stronger, but as you get further away, the shaking gets weaker.”
And, at five miles deep, the quake was actually fairly shallow in geological terms but still in line with the depth of other quakes in the area that have happened.
“It depends on the fault structure, but five miles deep is still pretty shallow,” Heidi Koontz USGS Public Affairs Specialist said. “So, you would be able to feel it farther and wider.”
“Five miles is pretty consistent with our other observations in the area that are better constrained,” Rubinstein agreed. “It’s consistent for what we’ve seen in the Delaware basin.”
About an hour after the main quake, a 3.0 aftershock was felt across the area.
According to the USGS, “This earthquake occurred in an area of known human-caused (induced) seismicity. The relationship between this earthquake and the ongoing energy development in the region is under examination.”
“There have been several studies that show you get increased rates of seismicity, not just with fracking, but general oilfield activities. It could be with wastewater injection or a variety of things,” Wilson said.
“A colleague of mine had a scientific article published at the end of last year or beginning of this year about earthquakes in this exact area,” Rubinstein said. “He showed very clearly a lot of these earthquakes appear to be connected to wastewater disposal, and less earthquakes are connected to hydraulic fracturing in the area.”
And, while there have been a number of earthquakes of various intensities the last several years, no one factor can determine when a quake might happen.
“Earthquakes east of the Rocky Mountains, although less frequent than in the West, are typically felt over a much broader region than earthquakes of similar magnitude in the west,” The USGS stated in a press release.
“It really depends on the pre-existing geology of the area, if you’ve got faults or stresses,” Wilson said.
“There certainly is not a lot of (natural) active seismicity in the area,” Rubinstein said. “The most recent earthquake that I know of in the area, that is certainly natural, is way down in Alpine, Texas, in 1995. It was a 5.7. There is natural seismicity near Socorro, but that’s related to the magma body there.
“You’re not going to get a lot of natural earthquakes in the area, but you can never eliminate the possibility that these earthquakes are natural,” he said.
If you felt the earthquake, or feel any others, scientists say it’s important to fill out a “felt report” via the USGS reporting site at https://earthquake.usgs.gov/earthquakes/eventpage/us70008ggn/tellus
Blake Ovard may be reached at firstname.lastname@example.org.
This content was originally published here.