Geologists closely monitoring surge in Arkansas earthquakes

October 29, 2011LITTLE ROCKThe Arkansas Geological Survey says it is stepping up its monitoring of seismic activity in central Arkansas after dozens of small earthquakes in the region. Six minor quakes were recorded Friday near Quitman, the latest of more than 50 temblors in October. The Friday tremors began with a 2.0-magnitude quake around 7:45 a.m. and peaked with a 2.5 quake later in the morning. The shaking follows more than 1,000 earthquakes centered between Guy and Greenbrier from September 2010 to July of this year, when the Arkansas Oil and Gas Commission ordered four gas disposal wells shut down and voted to create a large moratorium area in which no future disposal wells could be drilled. Geologists said the activity – which involves injecting pressurized liquid into the ground – was likely contributing to the shaking. The quakes between Guy and Greenbrier tailed off significantly in August, but more quakes began occurring in October closer to Quitman. It sits about 10 miles northeast of Guy. That distance is potentially concerning, warned Scott Ausbrooks, geo-hazards supervisor for the Arkansas Geological Survey. The Quitman quakes are occurring along the same line as the Guy-Greenbrier ones, but there’s a miles-long gap between Guy and Quitman in which no quakes have been recorded. That might suggest that the tension is building, possibly leading up to a larger quake centered on that gap along the fault. A similar-sized gap occurred on the southern end of the Guy-Greenbrier fault and it in February unleashed a 4.7-magnitude quake, the largest of any of the recent tremors. Anytime there is a gap in seismicity along an active fault, it “bears watching,” Ausbrooks said. “I’m not saying that’s what it is,” he said. “I don’t want to scare people and I don’t want to say it’s going to happen. It’s just something we’re looking at.” The 4.7 tremor was felt across Arkansas and in neighboring states, though no injuries or major damage was reported. It and the other hundreds of smaller quakes that rumbled the area helped convince the Oil and Gas Commission to take action. So why is the shaking continuing if the drilling has stopped? Ausbrooks has a few ideas, though he said the phenomenon is still very much under investigation. Officials have already placed one temporary quake-monitoring station near Center Ridge and he said another will likely be placed elsewhere in the region in the next two weeks. “We’re kind of beefing back up because of this renewed seismicity,” he said. Ausbrooks said the shaking could be purely natural. Earthquakes continued for years after drilling ended at the Rocky Mountain Arsenal in Colorado, where an injection well is thought to have initially triggered seismic activity.  –Arkansas Online
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5 Responses to Geologists closely monitoring surge in Arkansas earthquakes

  1. Nolan says:

    This is not good, if a Quake were to break either the East or West Levee systems or both of the Mississippi River a large area South would be devastated.

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    • zach says:

      I just remembered that on Thursday, October 20, 2011 A rare and record-breaking South Texas earthquake with a preliminary magnitude of 4.6 struck near rural Karnes County rattling homes and causing faint tremors in downtown San Antonio. The quake struck at 7:24 a.m. The U.S. Geological Survey said it was the largest earthquake on record for the area, surpassing a magnitude-4.3 shock recorded in 1993. A September earthquake in West Texas had a 4.4 magnitude and was centered just north of Abilene.The largest Texas quake occurred in 1931 when a magnitude-5.8 temblor struck near Big Bend.

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  2. Do you think that there will be some major seismic activity soon?

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  3. Greg Coleman says:

    We felt the quake in Oklahoma last night all the way to central Arkansas. I was awake and working on my blog when it hit. Not as severe here as the 4.7 in Arkansas in February 2011 but certainly enough to notice. The noise and shaking awakened my wife from her sleep.

    By my count that’s record shaking in Arkansas, Texas and Oklahoma this year. It seems like the frequency and intensity of the quakes are increasing. They’ve been promising us the big one on the New Madrid fault here for many years. We’re one day closer.

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