Texas has a history of earthquakes — but human activity is increasing their frequency

AUSTIN (KXAN) — In the wake of a magnitude 5.1 earthquake rattling near Midland Monday evening, Texas geology experts are giving further insight into some of the causes behind these quakes.

Monday’s magnitude 5.1 earthquake had its epicenter located in the area surrounding Ackerly, Texas, which is about 20 miles north of Midland. While out in West Texas, the United States Geological Survey (USGS) received reports from those in the Austin metro feeling the tremors.

Dr. Shelly Wernette is an assistant professor of instruction at Texas State University and works in the geology program. She said Texas’ vast size and geography results in some portions of the state having more natural seismic activity than others.

Out in West Texas near El Paso and the Rio Grande rift, that area is a “seismically active region,” Wernette said, adding historical data have revealed a number of historic earthquakes in that area dating back to the late 1800s and early 1900s.

In that region, magnitude 5.0 earthquakes and stronger ones aren’t unusual, she said. Here in the Austin area, she said there are some fault lines, but the region historically hasn’t had as much natural seismic activity akin to portions of West Texas.

“It’s true that we are not a very active state, and the area where this earthquake was — the Ackerly, Midland area — really is not historically a natural earthquake hotbed,” Wernette said. “It’s very unusual that we’ve had this earthquake…most recently, the earthquakes have been intensifying and becoming more common, and that’s very much a human-driven thing, rather than what our natural patterns have been.”

USGS data found more than 3,600 earthquakes have been reported in Texas since 1900 . While the vast majority of those are smaller in magnitude, USGS has revealed dozens have been recorded at a magnitude 4 level or greater.

Accounting for Monday’s magnitude 5.1 quake in Midland, it marks eight total earthquakes with magnitude 5 or greater since 1900.

Wernette said that typically, earthquakes landing around a magnitude 5 intensity aren’t strong enough to cause structural damage. Once you reach closer to magnitude 5.5, she said that’s when some damage become more plausible.

However, she did add that with some areas of Texas not built with specific earthquake protections, that can make them more vulnerable to structural effects. No injuries had been reported as of Monday evening, per NBC News.

When looking at the increased presence of quakes in non-seismically active areas, Wernette did note fracking is one of those human behaviors that can disrupt and cause seismic activity. She said anything that leads to high-press stress in the earth can lead to a quake, from fracking fluids during the fracking process itself to the water that comes up when drilling for oil and gas.

“Most of the earthquakes we’re seeing, especially the big ones, seem to be associated with the injection of wastewater or disposing of it in deeper rocks, rather than the actual creating of the fractures for oil and gas production,” she said. “But certainly, there’s little doubt in today’s world that the combination of water injection with fracking is associated with earthquakes.”

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