The most recent earthquake, a 2.7-magnitude quake, hit at 9:57 a.m. Wednesday. The epicenter was near the old Texas Stadium site in Irving.
The U.S. Geological Survey also confirmed there were several other earthquakes, ranging in magnitude from 1.6 to 3.6 on the Richter scale, in roughly the same area on Tuesday.
The first, a 2.3M quake, hit around 7:37 a.m. Tuesday.
SMU officials announced Wednesday afternoon that its seismology team would install 22 seismographs across Irving in the wake of the quakes. It was expected that 15 of the monitors would be deployed Wednesday, two on Thursday and five more on Friday.
"In the near term, our first step is to put out seismographs to confirm and refine the location of the quakes and define the faults in the area," said Heather DeShon, associate professor of physics at SMU in a statement. "Only after we get that data will we be in a position to investigate the potential cause of the earthquakes."
The cities of Dallas and Irving will form a task force to investigate the cause of the quakes.
Before 2008, there had been only one reported earthquake in what's called the Fort Worth Basin. Since 2008, there have been more than 100 in North Texas.
Many wonder if fracking has anything to do with them.
SMU seismologist Dr. Brian Stump says that is not yet part of the discussion, but disposed wastewater is not being ruled out.
"When they recover the oil and gas, there's fluids with…there's water with that, and they have to separate the water, and then they have to dispose of the water," said Stump.
"And when they do, that it can trigger…?" asked FOX4's Richard Ray.
"Historically, it has shown that in some places that they've triggered small to moderate earthquakes," said Stump.
About a year ago, SMU seismologists placed monitors in the Azle area during a flurry of quakes there.
There is one well very close to the old Texas Stadium site that's owned by Trinity East Energy, whose president, Steve Fort, told FOX4 on the phone Wednesday that "Science and common sense would tell you that this is not related to fracking."
Fort says the well was "drilled in late 2009 fracked once in 2010," and that there "…has never been any waste water injection…" at the well.
Irving ISD started earthquake safety drills Wednesday at its schools, and Dallas ISD is also reviewing its safety procedures.
FOX4 viewers reported feeling a strong 3.5M earthquake about 3:10 p.m. across North Texas on Tuesday. It was felt in Irving, Dallas, Mesquite, Arlington and Coppell.
That quake was followed by the strongest in the area in recent weeks -- a 3.6M quake just minutes before 7 p.m.
The fourth quake, a 2.9M, hit at 8:11 p.m., with the fifth, a 2.7M, happening just a minute later at 8:12 p.m.
They were followed by the sixth, a 1.7M quake at 9:54 p.m., the seventh, a 2.4M at 10:05 p.m., and the eighth, a 1.6M at 11:02 p.m.
A 3.1M quake hit at 12:59 a.m. Wednesday, a 2.3M hit at 1:24 a.m. and a 2.6M hit at 8:32 a.m.
All the quakes were centered in Irving except for the sixth one, which was centered in Farmers Branch.
A total of 28 quakes have shaken North Texas since late October.
For many, Tuesday's quakes were the first they'd ever felt.
"Actually, it was real scary, though," said Marty Livingston, who felt the quake. "Everybody was sitting in their chair. All of a sudden, you start swaying backwards and forward. And, you know, for people here, that's the first time being in one. So that kind of freaked everybody out a little bit."
Gloria Tinner has felt earlier quakes in Irving, but Tuesday afternoon's was different.
"It was harder than normal and lasted a little bit longer and rumbled, like everything…the walls, the floor, it shook," said Tinner. "I want to know what's the cause of it. What's going on? Why's this happening? It shouldn't be happening here."
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