Sam Alexander wasn’t the only one who noticed it at about 10:40 a.m. Wednesday, when he heard a big boom. The windows and patio doors of his Sanger area home rattled.
“I was just sitting here at my computer and my glass was just bouncing,” Alexander said.
His wife, Kelli Alexander, called him to report that she felt the boom where she was staying in Lindsay.
Residents from as far away as Aubrey, Gunter, Krum, Pilot Point and Valley View headed to Facebook to say they felt it and ask friends whether they felt it, too. Sanger Police Department officials said, while they had received a number of calls about the source of the noise, they had no idea what it was.
Officials at Lockheed-Martin later confirmed that the sound was likely a sonic boom.
“We were supersonic testing this morning,” said Mark Johnson, company spokesman.
Residents were concerned there may have been an earthquake because of the many small quakes that have been reported nearby this week, including one near Enid, Okla., at 1:36 a.m. Wednesday and two on Tuesday, one in Oklahoma City at 3:43 p.m. and one in Azle at 2:03 a.m.
At the National Earthquake Information Center, geophysicist Don Blakeman said smaller quakes — which often are heard as much as felt — don’t always make the U.S. Geological Survey’s “Did You Feel It?” page. But he made note of the time and place to search the data, just in case.
In recent weeks, there has been a swarm of at least 14 earthquakes in and around Azle, the largest of which measured 3.6 on the Richter scale, triggering an announcement from the Texas Railroad Commission that it would study the issue. Recent research has linked earthquakes to oil and gas production, particularly injection wells.
Sanger lies outside the main producing areas of the Barnett Shale, but is surrounded by a number of private and commercial injection wells — where shale production waste is disposed in other formations. According to the Texas Railroad Commission, two of Denton County’s commercial injection wells are located near Stony, close to the Denton-Wise County line. Another seven commercial injection wells are located in Cooke County.
This isn’t the first time Denton County residents have been rattled by mysterious big booms. Corinth residents reported a boom and a rumble at about 11:30 p.m. Feb. 6, 2008, with Texas earthquake experts calling the reports consistent with what could have been a small earthquake. The morning of Oct. 11, 2006, Denton County residents reported a similar boom, and while Lockheed said they were testing aircraft then, too, the source of the sound wasn’t determined.