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The Shawnee News-Star
  • Earthquake swarm: Seismic activity continues in central Oklahoma, survey says

  • Two years after an historic 5.6-magniute earthquake destroyed their Dale home, Jimmy and Margaret Snyder, although retired, started over financially and built a new home. They now have something they didn’t have before: earthquake insurance.
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    Two years after an historic 5.6-magniute earthquake destroyed their Dale home, Jimmy and Margaret Snyder, although retired, started over financially and built a new home. They now have something they didn’t have before: earthquake insurance.
    The couple’s home sustained irreparable damage in November 2011, which forced them to tear down their home of 40 years and rebuild.
    Their new home is built with rubber gaskets in the walls to help withstand future earthquakes, which might be why they haven’t noticed any recent tremors.
    “If they happen, they are very small,” Jimmy Snyder said, adding they don’t really think about earthquakes and what could happen.
    “If it’s going to happen, there’s not much you can do about it…we go about our lives,” he said.
    Studies show one to three magnitude 3.0 earthquakes or larger occurred yearly from 1975 to 2008 in Oklahoma, while the average grew to around 40 earthquakes per year from 2009 to mid-2013.
    The U.S. Geological Survey and Oklahoma Geological Survey are conducting collaborative research quantifying the changes in earthquake rate in the Oklahoma City region.
    Many areas of Oklahoma experienced damage from the historic 5.6-magnitude that occurred near Prague on Nov. 5, 2011, including the turrets at the historic Benedictine Hall at St. Gregory's University in Shawnee. Work to replace and repair the hall was recently completed.
    While damage reports were plentiful in 2011, almost 60 years earlier in 1952, a comparable magnitude 5.5, struck El Reno and Oklahoma City. More recently, earthquakes of magnitude 4.4 and 4.2 hit east of Oklahoma City on April 16, 2013, causing objects to fall off shelves.
    With scientists assessing the implications of this earthquake swarm for large-earthquake hazards, they are evaluating possible links between these earthquakes and wastewater disposal related to oil and gas production activities in the region.
    “We've statistically analyzed the recent earthquake rate changes and found that they do not seem to be due to typical, random fluctuations in natural seismicity rates,” said Bill Leith, USGS seismologist. “These results suggest that significant changes in both the background rate of events and earthquake triggering properties needed to have occurred in order to explain the increases in seismicity. This is in contrast to what is typically observed when modeling natural earthquake swarms.”
    An Oklahoma seismologist said earthquakes are going to be part of life for a while in the state and people here need to remain aware.
    “When I came to Oklahoma, I would do public outreach, saying that Oklahoma does have an earthquake hazard, and I got the blank stares and they didn't almost quite believe it,” remembered Austin Holland, seismologist with the Oklahoma Geological Survey, which co-issued the report. “A good takeaway from this is that still, the chances of a damaging tornado or damaging ice storm are greater than a damaging earthquake, but people need to be prepared for any hazard we face in Oklahoma.”
    Page 2 of 2 - Some residents in Prague, like Joe and Mary Reneau, whose two-story brick home was heavily damaged after the 2011 quake, don’t appear to be too alarmed about the USGS findings, even though some of their neighbors now call the couple every time their ground or house sways after a minor quake.
    The Reneaus, who had earthquake insurance, rebuilt their house nearly from the studs up. But even with the 33 steel piers now reinforcing their home, the earthquakes that have struck since 2011 have triggered hairline cracks in the concrete driveway and some of the brickwork on the back patio.
    As part of the study, what may be important to people living in the Oklahoma City region is that earthquake hazard has increased as a result of the swarm. The USGS calculates that ground motion probabilities, which relate to potential damage and are the basis for the seismic provisions of building codes, have increased in Oklahoma City as a result of this swarm.
    To more accurately determine the locations and magnitudes of earthquakes in Oklahoma, the OGS operates a 15-station seismic network.
    Data from this system, and from portable seismic stations installed in the Oklahoma City region, are sent in real-time to the USGS National Earthquake Information Center, which provides reporting on earthquakes worldwide.
    To learn more about earthquakes, go to www.usgs.gov or www.ogs.ou.edu.
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    The Associated Press contributed to this report.
     
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