March 21, 2014

Threat Still Looms for New Madrid Seismic Zone

Threat Still Looms for New Madrid Seismic Zone,

In a study published in late January of 2014 in both Science Mag and through the USGS Newsroom, two USGS Seismologists Morgan Page and Susan Hough argue that the recent activity in the New Madrid Seismic Zone is not aftershocks but in fact new earthquakes building new pressure. This isn't a new threat though, the USGS publicly released an article on the New Madrid Seismic Zone still being a concern way back in 2009- 5 years ago. That threat has not gone away.

Rolling Under New Madrid

"During 1811–1812, the New Madrid Seismic Zone experienced a sequence of three large intraplate earthquakes and at least one comparably sized aftershock. There have been no earthquakes of similar magnitudes since then. Using a combination of historical data dating back to the original large events and an epidemic-type aftershock sequence model, Page and Hough (p. 762, published online 23 January) found that the current low seismicity is not part of an aftershock sequence. Instead, despite low observable deformation rates, there is ongoing accumulation of strain, leaving the potential for large earthquakes in the region." -Editor's Summary of The New Madrid Seismic Zone: Not Dead Yet


"Roadways in the Mississippi Valley of Arkansas and Missouri (such as Interstate 55) could become impassable because of bridge failures and fissuring of road surfaces. Venting of large quantities of water, sand, and mud as a result of liquefaction could flood fields and roads and disrupt agriculture for weeks to months. Flooding of farmland, where agricultural chemicals are stored onsite, could contaminate rivers and streams. Failure of levees, especially during high water, would contribute to flooding, and failures of riverbanks could make the Mississippi River and its tributaries difficult to navigate for many weeks. The City of Memphis and the surrounding metropolitan area of more than one million people would be severely impacted. Memphis has an aging infrastructure, and many of its large buildings, including unreinforced schools and fire and police stations, would be particularly vulnerable when subjected to severe ground shaking. Relatively few buildings were built using building codes that have provisions for seismic-resistant design. Soil liquefaction and related ground failures are likely to occur in downtown Memphis along the Mississippi River and along the Wolf River that passes through Memphis. The older highways and railroad bridges that cross the Mississippi River, as well as older overpasses, would likely be damaged or collapse in the event of a major New Madrid earthquake. Some of the bridges and pipelines crossing the Wolf River might be damaged or destroyed. Although Memphis is likely to be the focus of major damage in the region, St. Louis, Mo., Little Rock, Ark., and many small and medium-sized cities would also sustain damage." -USGS

"I don't agree that this area is dying out," said Morgan Page, lead study author and a geophysicist with the USGS in Pasadena, Calif. "It's not going to go off anytime soon, but we do have evidence that more stress is being built up now. Eventually, that energy will have to be released in a large earthquake." -Thanks to Active New Madrid Fault Zone, Midwest Earthquake Risk Still Looms - "Even though we can't predict earthquakes, we can predict the rates of aftershocks over time," Page explained. "The frequency of aftershocks — smaller quakes that follow the big earthquake — decreases with time, known in seismology as Omori's Law. And in the New Madrid Seismic Zone, the aftershocks aren't following Omori's Law."

xoxo disaster girl

P.F.S. Links for the Curious

Threat of Earthquakes Occurring in Central United States Still Alive
New Madrid Seismic Zone Wiki
Missouri DNR Facts about New Madrid
USGS New Madrid

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