Repeated earthquakes this month in North Texas have prompted officials to inspect dams for possible cracks or loosened foundations.Eagle Mountain Lake’s dam is being inspected daily, and following a couple of Thanksgiving Day tremors in Palo Pinto County, Possum Kingdom Lake’s dam is expected to follow suit.The Eagle Mountain Reservoir manager is conducting daily inspections for signs of distress, said Chad Lorance of Tarrant Regional Water District.“Our dam safety engineer is monitoring all instrumentation at the dam for any indication of changes in foundation or embankment activity; there has been none to date,” Lorance said in an email to the Star-Telegram. “Our engineering department will be on site early next week to perform a crest survey of the dams to look for any signs of changes from previous surveys.”The latest earthquake to shake North Texas came at 12:14 a.m. Friday near Reno in Parker County, which at a 3.1-magnitude was the third strongest of 19 earthquakes to strike in November.Though no Reno residents clicked the Did You Feel It link on the U.S. Geological Survey’s website, nine people in Azle, four in Newark and three each in Springtown and Boyd reported sensing the quake. It’s not surprising that most people would sleep through the tremor; it takes at least a 4.5 to shake things up enough to cause damage, according to the USGS.A 3.6-magnitude quake struck at 1:58 a.m. Thursday about 10 miles north of Mineral Wells in Palo Pinto County, followed by a 2.8-magnitude tremor at 2:41 a.m. about 14 miles south-southwest of Jacksboro.The Lake Country Sunreported that the Possum Kingdom Lake dam must be inspected following any earthquake centered within 50 miles of the lake. The two Thursday quakes were within that radius.Determined to avoid problems, Tarrant Regional Water District has asked for advice from experts that include the Geological Survey’s seismologists and geophysicists, Lorance said.“We will also be contacting the Railroad Commission so we stay up to date on any oilfield related activity,” Lorance said.Some geological experts suspect a connection between injection wells and the outbreaks of earthquakes. Many of the recent earthquakes have occurred within a few miles of injection wells drilled to dispose of wastewater from natural gas wells in the Barnett Shale.But linking tremors to injection wells would take years of study and even then not all scientists agree that the wells are causing quakes. This report includes material from the Star-Telegram archives.
Terry Evans, 817-390-7620 Twitter: @fwstevans