The violent tremor woke people in distant cities on the
Although there were no official seismographs to document it, the event is estimated to have been a magnitude 7.7 quake. (A doctor in
It was also a sign of things to come.
The following month, an estimated magnitude 7.5 earthquake would strike the region, and two weeks after that, a third and final quake -- thought to be an even larger 7.7 -- would rock the area, severely damaging the town of
More than two centuries of relative quiet later, all three quakes easily stand as the strongest ever recorded east of the
The sequence of quakes is still remarkable to seismologists not only for its intensity and repetition, but also because of its middle-of-the-continent location, more than 1,000 miles from the earthquake-prone fringes of any tectonic plates.
"The crust here in the
Continued interest in the
Given its uniqueness and remaining mysteries, however, some scientists question whether those policies accurately reflect risk in the seismic zone.
A recent study contends that those living in the area today are still facing economic aftershocks from the historic outburst of earthquakes. The report -- released in October by scientists with the
Though the study focused on western
"It's definitely applicable to the whole area," Wang said.
As risky as
Those behind the study say properly gauging the region's earthquake risk is complicated by a shortage of data that directly applies to the area.
"One of the issues we have is that in the central
The study's authors said much of the data behind the
"We're not saying
'Not a dead system'
Other earthquake scientists, meanwhile, meet the report's conclusions with skepticism.
Cramer said the study did not interview scientists or hazard experts, noting that the supporting interviews centered on government officials, economic development agencies and business people.
Cramer said evidence indicated that the area was hit by major quakes about every 400 to 500 years, with similar episodes occurring around the years 900 and 1450.
"From a statistical point of view, the chance of a repeat of that [1811-caliber earthquake] is 7 to 10 percent in the next 50 years," Cramer said. "While not a great hazard, it's still a significant hazard, and one needs to prepare better rather than not at all for such eventualities."
Meanwhile, Cramer said, there's a 25 percent to 40 percent chance of the area experiencing a magnitude 6 earthquake over the same 50-year interval.
While it still holds the potential for the most devastation, the
From 1978 to 2008,
"We should've been more worried about
Despite evidence of "induced seismicity" in areas of oil and gas development, Herrmann said the
Even so, he said the long-quiet fault system was worth keeping an eye on:
"It's a sleeping giant we still have to worry about."
@_BryceGray on Twitter
(c)2016 the St. Louis Post-Dispatch
Visit the St. Louis Post-Dispatch at www.stltoday.com
Distributed by Tribune Content Agency, LLC.