South Texas town hit by 14 earthquakes in 13 days
When you think of hotbeds of seismic activity, you probably think of California, Japan or possibly South America — and likely not South Texas. But the small town of Falls City, which is about 40 miles southeast of San Antonio, had, as of Tuesday, been rattled by 14 earthquakes in the preceding 13 days.
All 14 earthquakes were recorded with a magnitude of at least 2.0 on the Richter scale, which is used to measure earthquake intensity. All 14 earthquakes occurred within 5 miles of Falls City. Several microquakes, which the U.S. Geological Survey classifies as an earthquake measuring less than 2.0 on the Richter scale, also have been recorded in Karnes County.
Overall, the 14 earthquakes have been relatively weak. Of those, 11 had a rating of less than 3.0 on the Richter scale. Quakes this small are generally difficult to feel, especially if they have a rating of less than 2.5. That being said, you’re more likely to feel them if you are near the epicenter.
The remaining three of the 14 earthquakes this month near Falls City had a rating above 3.0. The strongest earthquake registered at a magnitude 3.7, which happened at 2:07 a.m. Monday. The quake was centered just 2 miles southeast of Falls City.
Earthquakes of this magnitude are often felt by many people near the epicenter. However, according to the Geological Survey information page on this particular earthquake, only 18 people filed reports of having felt the temblor. The relatively low number of people reporting is likely because of two factors: Falls City is a rural town with a population of just over 500 people, and the quake happened when most people were asleep.
The Geological Survey also reports that the earthquake was felt as far away as San Antonio. Thankfully, this earthquake, as well as the 13 others, did not result in any damage.
Is fracking to blame?
Falls City lies in the Eagle Ford Shale, a swath of South Texas stretching from the Rio Grande near Laredo to the northeast, parallel to Interstate 35. The region has become important to oil production in Texas, and fracking is common there. Production in the area has been increasing: Both 2021 and 2022 saw an increase in drilling permits in the region.
Fracking involves injecting pressurized liquid into the ground to extract oil or natural gas. Critics of the extraction process say fracking’s disruption of the geological formations can trigger quakes.
According to the Geological Survey, fracking does cause small earthquakes, but the vast majority are microquakes that are not felt by humans. However, while fracking does produce oil and natural gas, it also leaves us with two byproducts: the fracking liquid and saltwater.
To get rid of the byproducts, they often are pumped into disposal wells, deep under the earth’s surface and far below groundwater or drinking water aquifers. According to the Geological Survey, this wastewater disposal process is what causes the larger earthquakes, the ones that can actually be felt by humans. On rare occasions, these quakes can even do minor damage.