Magnitudes for Oklahoma earthquakes shift upward, new record

Magnitudes for Oklahoma earthquakes shift upward, new record

PAWNEE, OK (KSWO) - The U.S. Geological Survey is updating the official magnitude of the September 3, 2016 Pawnee, Oklahoma earthquake to MW 5.8 (from 5.6), making it Oklahoma's largest recorded earthquake to date.

"USGS analyses indicate that the two earthquakes are very similar in size - to within typically-cited uncertainties of 0.1 magnitude units," said Gavin Hayes, USGS research geophysicist. "However, the 2016 Pawnee event is slightly larger than the Prague earthquake in 2011."

The magnitude revision is based on further in-depth analysis of seismic recordings. Changes in estimated magnitude for an earthquake are common in the hours-to-days following the event, as more data are analyzed in greater detail than is possible in the first minutes after the earthquake occurs.

"While the difference in size between the two events is less than 0.1 magnitude units," Hayes continued,  "rounding magnitudes to one decimal place means that the magnitude of the Prague earthquake is MW 5.7, and the Pawnee earthquake is MW 5.8."

Concurrently, the USGS is also updating the official magnitude of the November 6, 2011 Prague, Oklahoma earthquake to MW 5.7 (from 5.6). Questions regarding their relative size prompted a re-analysis of both earthquakes. Both updates are the result of comprehensive studies of the long-period, globally-recorded seismic data for these earthquakes, using consistent approaches and data sets for each event.

Precisely ranking the largest earthquakes in Oklahoma is difficult because seismic instrumentation has vastly improved over the last several decades. Other large, documented and felt earthquakes in Oklahoma include an instrumentally recorded 1952 event centered near El Reno, to which magnitudes of 4.9 to 5.7 have been assigned. Before the instrumental era, an 1882 earthquake in southern Oklahoma has magnitude estimates ranging from 4.8 to 5.7, based on the area over which it was felt.

Magnitude estimates can vary for a variety of reasons, including differences in methods used to compute magnitude, differences in data used, uncertainties in that data, differences in how that data is processed, and differences in our assumptions about the Earth structure through which seismic waves travel.

In a 'no-holds-barred' statement to the public today, state Rep. Richard Morrissette declared that the current practice of waste water injection -post fracking- is a failed method that should see a permanent moratorium for at least a 12-county region within the Mississippi Lime and be replaced by a process of waste water recycling.

"I am not surprised by the devastating 5.6 earthquake. A quake has been predicted by unbiased experts, while the opportunistic energy industry executives watched oil prices climb to $60 per barrel and announced their plans to increase fracking and disposal. If this is the tradeoff for some 'boom and bust' employment opportunity, I think our state should consider that in Oklahoma energy and the environment have now become competing interests and we can survive the loss of those jobs, and life-threatening earthquakes, but not clean water, soil and air. And as for giving back, ask people in communities where the oil industry is fracking if these wealthy companies leave behind future opportunities for laid-off employees to have enhanced quality of life such as improved infrastructure. It's not happening," Rep. Morrissette said.

"America burns our Oklahoma-produced fuel, so Americans via federal assistance can help pay for waste water recycling. In conjunction, the oil companies that are presently fracking can also pitch in some of the millions from state tax credits. We can develop a reasonable public-private funding formula to pay for recycling. The days of the oil industry leaders so cavalierly stating, 'We just can't recycle wastewater because it's too expensive! Not economically feasible!', are over. Damage from these quakes doesn't discriminate. 100% of Oklahoma was shaken to its foundation to bedrock on Saturday. Whether one can see significant cracks or sagging beams, or it's cosmetic, we have now had literally thousands of man-made earthquakes and there is some cumulative degree of stress damage to every structure from this repeated exposure. Earthquake insurance claims are being disputed, in some cases, so that leaves our citizens financially exposed to loss. The money earned by hard-working oilfield workers in the oil patch and throughout the state should be spent for family health care, college tuition and basic fundamental human needs, not for reconstruction of their homes," Morrissette continued.

Morrissette claims the petroleum industry "holds all of the cards here." The regulatory Oklahoma Corporation Commission "only takes action to curtail their activity in the midst of a crisis, as a reaction to a man-made earthquake." The U.S. Energy Information Administration estimates the oil industry will survive for a minimum of 25 more years, at current rates of consumption.

An interim study on options to wastewater recycling will be held on Tuesday, October 25, before members of the Energy and Natural Resources Committee in the Oklahoma House of Representatives in room 412C of the Oklahoma State Capitol.

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