Over the past year, there have been 44 earthquakes in the Dallas/Fort Worth area….17 in the past week. They have ranged from around 2.5 to 3.6 magnitude, and most of them have had epicenters in Irving. Many of us already have “Where were you when the last earthquake hit?” stories to swap, and others are curious as to what an earthquake feels like.
These recent quakes are mild compared to, say, the 6.7 magnitude California Northridge earthquake of 1994 or the Great San Francisco earthquake (magnitude 7.8) of 1906, but it has many wondering if something bigger might be coming up. Or how long the string of earthquakes will go on and why they are suddenly occurring so frequently in Texas and Oklahoma.
The most consistent epicenter was close to the old Texas Stadium where the Dallas Cowboys played. While area residents have often attributed the quakes to the implosion that demolished the stadium in 2010, there is a lot of speculation that these events started happening when oil companies started fracking activity in Texas and other parts of the country.
Irving is one city that lies on the Balcones Fault Zone, which runs along I-35 and passes by Austin, San Antonio and other cities. There are over 2,000 fracking wells situated near Irving. Fracking wells involve extracting gas and oil by boring equipment deep into the earth’s crust. The shale rock, once lubricated with high-pressure water, will more easily break apart and yield oil. Injection wells are used for disposing the drilling wastewater. While not all hydraulic fracking is done near fault lines, the Barnett Shale region in fact lies in the Balcones Fault Zone.
A 2012 study indicated that earthquakes caused by fracking could place stress on existing faults by making them more likely to rupture. Seismologists concur, however, that only a very small percentage of history’s recent earthquakes have ever been caused by fracking—and fracking is going on all over the world.
The increased incidence of earthquakes has prompted a number of questions that have never been explored until now. Building codes are being reviewed for ability to withstand earthquakes, and insurance companies are being besieged by inquiries about earthquake insurance. The City of Dallas has created a multidisciplinary task force to collect data and discuss the matter in depth. A panel of SMU seismologists will present its findings later this month, in hopes of making more sense of recent events.
As the debate rages on whether earthquakes have been caused by nature, by fracking or by some other inexplicable force—there is no need to panic. The most recent earthquakes have all been less than 4.0, which is a fairly minor number, and California had 600 earthquakes within a two-day period last year. So let’s get ready to rumble some more, and go about our daily lives.