Two earthquakes shake Fashing areaFree Access

LEON ZABAVA

OIL AND GAS EDITOR

On Saturday, January 6, 2018, there was a report of an earthquake in Atascosa County north of Fashing.

According to the Bureau of Economic Geology at the University of Texas at Austin,  there were actually two earthquakes in that area.

The January 6 occurrence was at 3:37:17 that Saturday afternoon and its depth relative to ground surface was 3.2 kilometers and was a 3.4 magnitude quake.

There was a follow-up earthquake in the vicinity of Fashing on Sunday, January 7 at 8:56:56 in the morning and its depth level was 4.3 kilometers below the surface with a magnitude of 2.6.

Atascosa County Sheriff David Soward said, “We were notified about the earthquake by the news media Saturday in Atascosa County but my office did not receive any calls from any residents regarding the earthquake or any damage it may have caused.”

Information regarding earthquakes is administered through what is called TexNet. This is an earthquake monitoring program run by the Bureau of Economic Geology at the University of Texas at Austin to help locate and determine the origins of earthquakes in Texas.

Information sources were Alexandros Savvaidis, Ph.D., Manager of Texas Seismological Network (TexNet) and Mark W. Blount, CFRE, External and Governmental Affairs, Bureau of Economic Geology, The University of Texas at Austin.

Dr. Savvaidis said that the Fashing area is a well-known area for earthquake events and that the TexNet program is working to get more seismic stations in locations such as Fashing in Atascosa County.

“We’re doing this to make sure we’re getting a better understanding of the seimic activity in the area so we can report the type of information that is necessary.” said Dr. Savvaidis. “We record the ground motion and any type of movement happening in the area.” Savvaidis said that this information can assist in getting information out to the public in a timely fashion. “We put this information on our website,” said Savvaidis. “Two seismic stations were deployed into the area (near Fashing) in 2017, the most recent one being deployed before Christmas and we have a plan to deploy at least another one, maybe two.”

Fashing, being in the Eagle Ford Shale area, questions are if these occurances could be oil related.

Therefore the question frequently arises that if drilling for oil and gas causes or triggers earthquakes.

Drilling itself never causes earthquakes, but some quakes are caused by various activities associated with petroleum production. Research carried out by the Institute for Geophysics – The University of Texas at Austin (UTIG) scientists suggests that earthquakes in some parts of Texas may be induced by the pumping of fluids at oil and gas fields, or by the injection of fluids, either to enhance production or to dispose of fluid wastes, such as flowback brines from hydrofracturing operations. The earthquakes in the Fashing-Pleasanton area southeast of San Antonio are almost certainly caused by or triggered by pumping.

If pumping oil and gas causes earthquakes, is it safe to continue pumping?

Yes, it is usually safe. Earthquakes induced by the injection or pumping of fluids from wells are generally very small; most have magnitudes of 3 or less. Moreover, while tens of thousands of oil and gas wells exist in Texas, only a few fields show any evidence that oil and gas pumping induces earthquakes. However, a few apparently induced or triggered earthquakes in Texas have had magnitudes of 4.5-4.8; in urban areas such events pose a concern

A seismometer is used to detect the waves of an earthquake. The idea behind a seismometer is fairly simple- it’s just a weight attached to a frame. Motions of the ground cause the frame to move, and any movements of the frame relative to the weight are translated into electrical signals. Most seismometers are permanently attached to a recording device; the combination is called a seismograph.

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