In the minutes after 2:37 p.m. Sunday, about 100 folks reported what appeared to be a small earthquake in McDonald County.
Gregg Sweeten, mayor of Pineville and director of McDonald County Emergency Management, said the earthquake was felt from the west side of McDonald County over to Rocky Comfort. Sweeten said people in Gravette as well as Monett were also talking about experiencing the quake.
The 3.4 magnitude earthquake's epicenter was located 12 miles west of Perry and 21 miles east of Enid, Okla. The eipcenter is 175 miles west-southwest of Pineville.
The United States Geological Survey says earthquakes in the central and eastern U.S., east of the Rockies, are typically felt over a much broader region than in the western U.S. An earthquake can be felt over an area as much as 10 times larger than a similar magnitude earthquake on the West Coast.
According to the USGS, McDonald County has a very low earthquake risk. The database shows that there is a 0.20 percent chance of a major earthquake within 50 kilometers of McDonald County within the next 50 years.
Oklahoma has its own set of earthquake faults, USGS says. One of these faults, the Meers Fault, can be seen from the air near Lawton. It produced an earthquake estimated at 7.0 on the Richter scale approximately 1,600 years ago.
Earthquakes occur all over Oklahoma but the greatest concentrations are just west and south of Oklahoma City.
The USGS website on earthquakes notes that "within the central and eastern United States, the number of earthquakes has increased dramatically over the past few years. Between the years 1973--2008, there was an average of 21 earthquakes of magnitude three and larger in the central and eastern United States. This rate jumped to an average of 99 M3+ earthquakes per year in 2009--2013, and the rate continues to rise. In 2014, alone, there were 659 M3 and larger earthquakes. Most of these earthquakes are in the magnitude 3--4 range, large enough to have been felt by many people, yet small enough to rarely cause damage. There were reports of damage from some of the larger events, including the M5.6 Prague, Oklahoma earthquake and the M5.3 Trinidad, Colorado earthquake."
An article in the magazing Science reports on a study to see if new methods of extracting oil and natural gas may be causing a recent increase in earthquakes. The study, which studied what it calls "An unprecedented increase in earthquakes in the U.S. mid-continent began in 2009," concludes "Many of these earthquakes have been documented as induced by wastewater injection. We examine the relationship between wastewater injection and U.S. mid-continent seismicity using a newly assembled injection well database for the central and eastern United States.We find that the entire increase in earthquake rate is associated with fluid injection wells."
The New Madrid Fault which lies roughly along a line between Saint Louis and Memphis is of some concern to USGS. Energy waves from a major earthquake along this fault could easily reach parts of Missouri, producing damage. A cluster of earthquakes in 1811-1812 produced some of the largest earthquakes seen in the United States.
There are as many opinions as there are scientists about when the "really big one" will hit the New Madrid again, perhaps as much as an 8.0 or higher. Most scientists agree that a quake of 6.0 is likely to occur within the next 35-40 years.
General News on 07/02/2015