Apocalyptic Midwest quake predictions overblown
Earthquake unlikely to hit small town this century, or the next.
Fri, Oct 22, 2010 at 09:22 AM
Fears of the next big earthquake in America's heartland are just a bunch of hype.
That's according to a new book that explains how there's little scientific evidence to back up the apocalyptic predictions that a set of faults in the Midwest that set off huge quakes a couple centuries ago, known as the New Madrid Seismic Zone, could rupture violently again soon.
In "Disaster Deferred: How New Science Is Changing Our View of Earthquake Hazards in the Midwest"(Columbia University Press, October 2010), author and geologist Seth Stein tries to reassure folks living near the infamous New Madrid faults by explaining the science behind earthquakes in the middle of the continent.
Stein, of Northwestern University in Evanston, Ill., said there's little scientific evidence for the fear of "the next big one" in the New Madrid seismic zone — the site of some of the strongest earthquakes ever recorded in the continental United States, nearly 200 years ago.
In 1990, a widely touted prediction said a big quake would hit the area, and a media circus ensued. The prediction proved false but highlighted the fear and hype surrounding the idea of a big Midwestern earthquake, Stein says.
As the 200th anniversary of the earthquakes that occurred in the area of New Madrid, Mo., approaches, talk of catastrophe is rising again.
"It's said that the 1811 and 1812 earthquakes were the biggest in U.S. history, which isn't true," Stein said. "Or that they rang church bells in Boston, which isn't true. And that another huge earthquake is on the way, which there's no reason to believe."
The findings detailed in "Disaster Deferred" come from more than 20 years of research regarding the New Madrid seismic zone. The book describes Stein's scientific adventures that ultimately found no sign that large earthquakes will hit the New Madrid area within the next several hundred — or even thousands — of years.
"We, of course, can't say there will never be another New Madrid earthquake like the ones in 1811 and 1812, but there's no sign of one coming. The next could be thousands of years or tens of thousands of years in the future," Stein said.
The seismic zone today generates about 200 tiny quakes annually, but it also let loose a magnitude 4.1 quake in February 2005 and a magnitude 4.0 quake in June 2005. An estimate from the 1980s asserted a 9-in-10 chance of a magnitude 6 or 7 temblor occurring in this area within the next 50 years. Later estimates have reduced this probability somewhat, although there is no consensus among researchers.
The Mississippi River is somewhat to blame for the 1811 and 1812 quakes, according to a study released earlier this year. Sediment erosion from the river released a great weight off the fault, allowing the Earth to buckle and the faults to rupture. That study also suggests that an earthquake is unlikely to hit anytime soon on the same faults in New Madrid.
Some seismic risk remains, however. A 2007 study discovered that an ancient, giant slab of Earth called the Farallon slab that started its descent under the West Coast 70 million years ago is causing mayhem and deep mantle flow 360 miles (579 kilometers) beneath the Mississippi Valley where it effectively pulls the crust down nearly half a mile (1 km).
The Farallon plate will continue to descend into the deep mantle and thus cause mantle downwelling in the New Madrid region for a long time, suggesting there will be seismic risk in the New Madrid region that will not fade with time, the authors of that study said.
This article reprinted with permission from Our Amazing Planet.
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