South Texas earthquakes likely triggered by shale boom, researchers say
Fuel Fix ^ | August 27, 2013 | Jennifer Hiller freerepublic.com
Earthquakes in the Eagle Ford Shale region — including a 2011 quake felt in San Antonio — are likely being triggered by increased oil extraction, according to a new research paper from the University of Texas at Austin. A two-year survey of seismic activity links small quakes in South Texas largely to the upswing in the production of oil and brackish water that flows up alongside hydrocarbons.
However, researchers concluded the quakes were not related to hydraulic fracturing, the process of pumping water, sand and chemicals at high pressure to crack open dense shale rock. Nor do disposal wells, where companies discard hydraulic fracturing fluids and brackish water found underground, appear to trigger most of the quakes...
...The most powerful quake included in the survey was an Oct. 20, 2011 event centered at Fashing in southeastern Atascosa County — a magnitude 4.8 earthquake that was felt throughout the San Antonio area, and as far south as Kingsville and as far north as Burnet. No injuries or significant damage was reported, although in Atascosa County it rattled windows, cracked masonry and knocked items out of cupboards.
Cliff Frohlich, associate director and senior research scientist with UT’s Institute for Geophysics, said the Fashing earthquake coincided with a significant increase in nearby oil and water extraction — something mirrored in previous quakes in Fashing in 1973 and 1984, other times when oil and gas production increased.
Most of the South Texas tremors have been too small to feel. And most of the quakes have been centered in Fashing, as well as in Karnes and Dimmit counties, two areas of heavy oil field activity... |
