Worst Earthquake Horror Happened in New Madrid Fault
One of the worst earthquake horrors that ever happened in the United States did not take place in Alaska or California, but in the middle of the country around 200 years ago and was centered where there are seven states linked around the Mississippi River Valley today. Seismologists who work at the United States Geological Survey think they have found evidence that the New Madrid fault line is still very much alive. It is the area that causes the earthquake and numerous aftershocks of 1811 to 1812.
But thankfully back in that time period, there were not that many people living in the area, but for the ones who were, the earthquakes had to have been a terrible experience, stated Susan Hough, who is one of the seismologists with the USGS in Pasadena, California. She authored a paper along with a fellow seismologist, Morgan Page, and it was printed in the most recent issue of the journal Science. Hough explained that because there were no seismometers at that time in history, scientists are only able to guess at what the strength of the quakes was. They believe the strongest were at least at magnitude 7.
The earthquakes were felt all the way to the East Coast, Hough stated, there were church bells ringing in Charleston, South Carolina and also in Boston. One of the recorded fatalities was in fact near Louisville, Kentucky. That is actually fairly far from the New Madrid zone area. The USGS explained that the first of size 7 quakes hit at around 2 a.m. on Dec. 16, 1811. There were then two others that followed on Jan. 23, 1812 and Feb. 7, 1812. Sporadic shaking went on through March of 1812 and aftershocks that were strong enough to be felt continued to occur up to the year 1817.
However, when one looks at a map of the region, the New Madrid fault area appears to be an unlikely place for earthquakes because it is right in the middle of the North American plate. The state of Alaska and the West Coast of the U.S., by contrast, are at the edge of a plate, which is a more regular place to find high seismic action. But the New Madrid fault has had some major quakes in its history. Researchers have geologic proof of numerous major earthquakes of about magnitude 7 and 8 hitting the zone over the past 5,000 years.
Out of the various quakes, it was reportedly that the Mississippi River actually ran backwards. Earthquake fissures were reported to have gone as long as five miles and ended up swallowing some people entirely. However, there was not a lot of destruction done to any structures which were man-made because the area was sparingly populated at the time.
After that succession of big quakes and aftershocks, in 1843 and 1895 there were earthquakes with magnitudes of around 6 to 7, scientists have projected. Some even believe that this string of quakes is all linked as a long series of aftershocks coming from that original 1811 quake.
In the study that Hough and Page done, they reexamined the information about the earthquakes and compared it to what usually happens after quakes as defined by the Omori decay law. That is an established set of equations which forecasts how the rate of aftershocks should decline with time. Their calculations, instead shown that for all those post 1811/1812 quakes to have been all aftershocks there should have been an average of around 130 earthquakes of magnitude 6 or higher between 1811 and 2011. There have not been that many quakes of that size, but there also have not been any earthquakes that huge in the past 100 years. So the two authors state that the hypothesis that any current earthquake movement around the New Madrid region is from aftershocks from the 1811/1812 series is a failure. If they were aftershocks, these quakes would be releasing some strain and lowering the earthquake hazard in the area. Instead, this brand new research shows that the strain is continuing to increase in the New Madrid zone, and so the earthquake danger continues to stay high.
By Kimberly Ruble