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Posted on 01/22/2003 6:09:29 AM PST by John H K
Scientists from the U.S. Geological Survey (USGS) and the Center for Earthquake Research and Information at the University of Memphis have updated their expectations for earthquakes in the New Madrid Seismic Zone.
The new forecasts estimate a 7 to 10 percent chance, in the next 50 years, of a repeat of a major earthquake like those that occurred in 1811-1812, which likely had magnitudes of between 7.5 and 8.0.
There is a 25 to 40 percent chance, in a 50-year time span, of a magnitude 6.0 or greater earthquake.
The earthquake probabilities in this region have changed considerably since the most commonly cited forecast published in 1985. The new probabilities show an increased chance of larger (7.5-8.0 magnitude) earthquakes and a lesser chance of magnitude 6.0 and greater earthquakes. Meanwhile, estimates of the hazard, or potential for damage caused by shaking, have changed much less. A fact sheet with the new information is available on the web at: http://pubs.usgs.gov/fs/fs-131-02/.
"More than fifteen years of research has given us the information to allow us to update our forecasts. But even though the chances of a mid-sized earthquake are reduced, the chances of a devastating earthquake in the region have risen," said USGS scientist Eugene Schweig. "Given this new information, people should absolutely not drop their guard. The threat of an earthquake to Mid-America is still very real."
The New Madrid seismic zone is an area of frequent small earthquakes that stretches along the lower Mississippi Valley from just west of Memphis, Tennessee into southern Illinois. It also was the location of a sequence of three or four major earthquakes in 1811 and 1812.
Major earthquakes in the range of magnitude 7.5 to 8.0 are capable of causing widespread damage over a large region. Magnitude 6.0 earthquakes can cause serious damage in areas close to the earthquake?s epicenter because the hazard (chance of damage in a given area) depends not only on earthquake size, but also on where the earthquakes occur and local soil conditions.
In Memphis and throughout the Mid-America region, the USGS is improving its earthquake monitoring and reporting capabilities through the Advanced National Seismic System (ANSS), a nation-wide network of modern strong motion seismometers that can provide emergency-response personnel with real-time "shaking" information within minutes of an earthquake.
ANSS stations assist emergency responders within minutes of an event showing not only the magnitude and epicenter, but where damage is most likely to have occurred.
Ten new ANSS instruments were recently installed in the Memphis area, 20 have been installed across the mid-America region, and more than 175 have been installed in other vulnerable urban areas outside the central U.S. to provide real-time information on how the ground responds when a strong earthquake happens.
"The ultimate goal of ANSS is to save lives and ensure public safety," said Dr. John Filson, USGS Earthquake Program Coordinator. "This information, already available in Southern California, is generated by data from seismic instruments installed in urban areas and has revolutionized the response time of emergency managers to an earthquake, but its success depends on further deployment of instruments in other vulnerable cities."
In 1997, during the reauthorization of the National Earthquake Hazards Reduction Program, Congress asked for an assessment of the status and needs of earthquake monitoring. The result was the authorization of ANSS to be implemented by the USGS. The system, when fully implemented, would integrate all regional and national networks with 7,000 new seismic instruments, including 6,000 new strong-motion sensors in 26 at-risk urban areas. To date, approximately 350 instruments have been installed nationwide.
New USGS National Seismic Hazard Maps depict these hazard or likelihood of ground shaking. The USGS and its partners in universities and state geological surveys are preparing more detailed hazard maps for Memphis and other areas that include the effects of local soil conditions. For more information see http://geohazards.cr.usgs.gov/eq/.
The goal of USGS earthquake monitoring is to mitigate risk - using better instruments to understand the damage shaking causes and to provide information to help engineers create stronger and sounder structures that ensure vital infrastructures, utility, water, and communication networks keep operating safely and efficiently.
As the Nation's science agency for natural resources, hazards and the environment, the USGS is committed to meeting the health, safety and knowledge needs of the changing world around us.
http://geohazards.cr.usgs.gov/eq/
Interesting in that a couple of recent studies argue that the maximum magnitudes of the largest New Madrid quakes in the 1811-1812 series were smaller than some of the outlandish estimates seen previously; but no one has the largest smaller than 7.3. However, if that estimate is correct, it's now not the largest known earthquake in the lower 48; San Franscisco 1906 and Ft. Tejon, both on the San Andreas, would then be more powerful.
To my knowledge these areas have NOT built to what is typically thought of as California earthquake standards. When we discussed this topic a while back, one person challenged these thoughts. I don't remember the particulars, but I do believe there is serious cause for concern.
Only 31 years to go!
The new forecasts estimate a 7 to 10 percent chance, in the next 50 years, of a repeat of a major earthquake like those that occurred in 1811-1812, which likely had magnitudes of between 7.5 and 8.0.
This topic was posted , thanks John H K.
Well, Global Warming Climate Change will kill us all well before that earthquake gets here.............
Not only that, it will *cause* the quake!!! /sarc
I live near Martinsville, Indiana. We are very well aware of the probability of this occurring again here. My house, according to the USGS sits absolutely smack dab centered on a small fault called the Mt. Carmel fault, it follows just north of the White river basin and when you zoom in, the line is drawn through my house directly.
Just switched home owners insurance last week, went with Erie Insurance. Got a funny look from the writer who was quoting it about the cost of brick veneer siding from an earthquake and what was covered on a standard policy. For what little they wanted to add earthquake coverage I said put it on. She kinda thought that was funny I think but gladly took the extra money. Hope she’s right and I’m wrong TBH.
Sorry about the news. Glad to hear you got coverage
I read a lot about the New Madrid quakes. I think the scientists don’t even want to imagine how bad a quake so severe as the worst of 1811-12 could be. There is something called Reelfoot Lake formed when a large chunk of land in Tennessee dropped about 20 feet.
https://www.reelfoot.com/new_madrid_earthquake.htm [This site has vivid descriptions from that time.]
https://en.wikipedia.org/wiki/1811%E2%80%931812_New_Madrid_earthquakes [ This article has a number of clickable links.]
http://www.new-madrid.mo.us/102/Earthquakes-of-1811-1812 [This is the official New Madrid town site. Click the words “Strange happenings during the earthquakes” in the green box to the left.]
After reading these links, all I can say is Heaven help the poor people in the Mississippi basin if they are ever hit with comparable quakes with current buildings.
I was in a 7.5 in Mexico City (1957) which only killed about 150 people and collapsed very few buildings. That earthquake had a rolling quality like being on a NY subway train , and lasted for around a minute+. Mexico City is located on a mud lake bed so it quakes and oscillates rather than shudders. I was in the Mineral, VA earthquake (5.5), and where I was it was probably about 4. The wall and bed shuddered very intensely for about 15 seconds. The area where I was has hard clay on bedrock.
While researching this topic I found that Caracas, Venezuela had experienced a severe earthquake during that time that killed 20,000 people. These major earth convulsions can be felt over a wide area and affect different faults at the same or near same times. The great Lisbon earthquake and tsunami occurred about a month before the worst earthquake in Boston, USA. The great Pelee volcano eruption in Martinique that killed over 30,000 people was a day after one in nearby St. Vincent that killed 2 to 4,000. And during that year Santa Maria in Guatemala killed 5,000 and at least 2 other Caribbean Plate volcanoes were also active.
Thanks for the post.
The Mississippi river flowed backwards in come places due to
the New Madrid Fault quake around 1811.
The course of the river was also changed in one location.
I find it pretty interesting that church bells in Boston
rang due to that quake.
It’s just worries me all the building up of the areas
along that fault line, since that day. We could be
looking at a lot of death.
You know this, but others passing by might not.
Appreciate the informative links.
Thank you for a great link. There are 20 accounts here and I have already copied and read 4 of them. Hope to write a book some day where I can use these memories.
“Well, Global Warming Climate Change will kill us all well before that earthquake gets here.............”
If our marxist leaders don’t do it first.
I will have my Mississippi shaken, not stirred, please!
I was raised in the New Madrid quake zone, 60 miles east of Memphis.............
My pleasure. I looked at a few of ‘em, there was text missing here and there. I guess, considering the age of the original clippings, not bad.
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