http://news.yahoo.com/s/ap/20081128/ap_on_re_us/arkansas_earthquakes
Expert: Small Ark. earthquakes could be warning
LITTLE ROCK, Ark. – A series of small earthquakes that rattled central Arkansas in recent weeks could be a sign of something much bigger to come.
By this weekend, seismologists hope to install three measurement devices to gather data about future temblors in the area. That information could show whether the rumbles come from heat-related geological changes or from an undiscovered fault — which could mean a risk of substantial earthquakes in the future. "The potential for generating a high-magnitude earthquake is real," said Haydar Al-Shukri, director of the Arkansas Earthquake Center at the University of Arkansas at Little Rock.
Five earthquakes ranging in magnitude from 2.2 to 2.7 have hit central Arkansas this month. Quakes with a magnitude of 2.5 to 3 are typically the smallest felt by people. While hundreds of earthquakes occur each year, including several in Arkansas, the location of the recent ones give Al-Shukri pause. Arkansas quakes generally occur in the state's northeast corner, part of the New Madrid Seismic Zone, where three temblors with magnitudes of around 8 struck during the winter of 1812 and smaller ones continue today.
But central Arkansas does not have any seismic history, Al-Shukri said. "It is abnormal. It is significant," he said. "We need to carefully watch this activity." The area does not have any permanent seismograph, so researchers asked the University of Memphis in Tennessee if they could use its portable equipment. The nearest seismographs aren't close enough to provide the detailed readings scientists need to determine what could be causing the tremors or properly locate their origin, said Scott Ausbrooks, the geohazard supervisor for the Arkansas Geological Survey. "I don't know if you've looked at a map of where these events are located, but they've got a scatter on them," he said. "We're thinking this is probably the inherited error built in when you try to locate events of this small a magnitude from that far away."
Ausbrooks said officials would install the three seismographs around Magnet Cove, a Hot Spring County community near where a magnitude-2.7 earthquake hit on Nov. 1. Residents told police dispatchers they heard what sounded like an explosion. One possible culprit could be a hydrothermal quake, caused by extremely hot fluid pushing into rocks under the surface. The hot fluid percolates into the cracks of the rocks and causes movement, Al-Shukri said.
That theory matches the geologic history of the area. Central Arkansas is home to Hot Springs, a city that grew up around its namesake spas. The springs have 143-degree waters rushing to the surface continuously. If that's the case, the earthquakes likely wouldn't pose a drastic danger to the area, Al-Shukri said. At their strongest, such quakes reach only a magnitude of 5, the U.S. Geological Survey's threshold for "moderate."
However, if the earthquakes are caused by a previously unknown fault, that could mean a much more powerful temblor in the future. A recently discovered fault in eastern Arkansas near Marianna caused an earthquake with a magnitude of between 7.2 and 7.5 in the past 5,000 years, Al-Shukri said. That could cause widespread, heavy damage. "Now, it's not active, but in geologist time, that's yesterday," he said. Ausbrooks wouldn't speculate on what could be causing the earthquakes, saying he wanted to see what data the seismographs capture. However, he acknowledged an unknown fault could be running through the area.
"There are numerous faults across the state, both known and unknown," Ausbrooks said. "This area has got a lot of faults associated with it from the mountain building of the Ouachitas, but they're considered inactive."
I know that somehow this is all Bill and Hillary's fault.
I don't think that the Bill and Hillary Fault, Michael. It more likely the New Madrid Fault, probably brought here by illegal Hispanic immigrants.
Seriously, there's this:
THE FAULT IS ACTIVE, AVERAGING MORE THAN 200 MEASURED EVENTS per YEAR (1.0 or more on the Richter scale), about 20 per month. Tremors large enough to be felt (2.5 - 3.0 on the Richter scale) are noted annually. Every 18 months the fault releases a shock of 4.0 or more, capable of local minor damage. The most recent registering 4.3 along the New Madrid Fault on Thanksgiving evening, 1996, which was felt by citizens in the states of Missouri, Arkansas, Tennessee and Kentucky, Illinois and Mississippi. Magnitudes of 5.0 or greater occurring about once per decade, can do significant damage, and be felt in several states.
THE HIGHEST EARTHQUAKE RISK in the UNITED STATES outside the West Coast is along the New Madrid Fault. Damaging tremors are not as frequent as in California, but when they occur, the destruction covers over more than 20 times the area because of underlying geology.
A DAMAGING EARTHQUAKE in this AREA, 6.0 or greater, occur about every 80 years (the last one in 1895). The results would cause serious damage to schools and masonry buildings from Memphis to St Louis.
A MAJOR EARTHQUAKE in this AREA, 7.5 or greater, happens every 200- 300 years (the last one in 1812). There is a 25% chance by 2040. A New Madrid Fault rupture this size would be felt throughout half the United States and damage 20 states or more. Missouri alone could anticipate losses of at least $6 billion from such an event.
THE GREAT NEW MADRID EARTHQUAKE OF 1811-1812 was actually a series of over 2000 shocks in five months, five of which were 8.0 or more in magnitude. Eighteen of these rang church bells on the Eastern seaboard. The very land itself was destroyed in the Missouri Bootheel, making it unfit even for farmers for many years. It was the largest burst of seismic energy east of the Rocky Mountains in the history of the United States and was several times larger than the San Francisco quake of 1906.
WHEN WILL ANOTHER EARTHQUAKE HAPPEN THE SIZE OF THOSE IN 1811-1812? Several lines of research suggest that the catastrophic upheavals like those in 1811-12 visit the New Madrid region every 500-600 years. Hence, emergency planners, engineers, and seismologists do not expect a repeat of the intensity of the 1811-12 series for at least 100 years or more. However, even though the chance is remote, experts assign a 3% probability of a major earthquake by the year 2040. Earthquake probabilities for known active faults always increase with time, because stresses within the earth slowly and inexorably mount, year by year, until the rocks can take no more, and sudden rupture becomes inevitable.
OUR GREATEST CONCERNS ARE THE 6.0-7.6 SIZED EVENTS, which do have significant probabilities in the near future. A 6.0 shock has a 90% chance by the year 2040. Damaging earthquakes of this magnitude are a virtual certainly within the lifetimes of our children.
LINK (//%22http://www.scchealth.org/docs/ems/docs/prepare/newMadrid.html%22)
I was living in Pittsburgh when an earthquake centered on the PA/Ohio border hit. Down in the valleys, people felt the movement because the greater water saturation transmitted the vibration very well. But I was on a ridge that morning. It sounded like a heavy truck hit a series of potholes in the roadway outside, but there were no potholes.
quote:
Originally posted by Ed W
I don't think that the Bill and Hillary Fault, Michael. It more likely the New Madrid Fault, probably brought here by illegal Hispanic immigrants.
The reason this is newsworthy is that it's not the New Madrid fault. Seismologists seem to think there's either something very strange going on or there's an as-yet undiscovered fault southwest of Little Rock.
The New Madrid fault ends a couple hundred miles northeast of Little Rock.
Of course, any major quake on that fault would have significant effects at least that far, as the energy from earthquakes in the less fault-riddled part of the country east of the rockies dissipates much more slowly, thus increasing the affected area compared to a similar sized quake in California.
The story says these new ones are not part of what is commonly known as the New Madrid fault.
These tremors are in a new area of the state that hasn't had any tremors before.
I blame Obama and his message of change.
"When the mode of the music changes, the walls of the city will shake"
Plato
3 seismographs are being added this weekend in Central Arkansas to track the activity. The latest quake was a 2.2 on November 25. The epicenter was southeast of Hot Springs, closer to Malvern.
The alternate theory to it being hydrothermal activity is tectonic plate shifting.
If Arkansas gets more earthquakes, does that mean it can send the twisters to California?
OK, I stand corrected. But could we pin the fault on my teenage son? He seems to be responsible for numerous disasters around our house.
quote:
Originally posted by Ed W
OK, I stand corrected. But could we pin the fault on my teenage son? He seems to be responsible for numerous disasters around our house.
I am sure your teenager is responsible for many social ills, but has he been seen in Arkansas?
I was thinking about it while eating a McNugget and it occurred to me that it could be related to the chicken industry. I bought it from the McDonalds in front of Wal-Mart. The fries reminded me of all the French restaurants in the Hot Springs area.
I am now worried that our neighbors to the right could cause real damage to our planet.
I say we get the Oklahoma National Guard on the border stat.
Great...now the earthquakes have come to Oklahoma City.
http://www.tulsaworld.com/news/article.aspx?subjectid=12&articleid=20081202_12_0_OKLAHO980844
Earthquake shakes OKC area
By The Associated Press
Published: Tuesday, December 02, 2008
OKLAHOMA CITY — A small earthquake rattled homes in the Oklahoma City metro area Monday night, authorities said. There were no immediate reports of damage or injury with the quake, which struck about 8:50 p.m.
The temblor registered 2.7 on the Richter scale, Amie Gibson, a research specialist with the Oklahoma Geological Survey, said.
The survey received reports from Tinker Air Force Base and residences in Midwest City, Del City and as far west as N.W. 122 Street and MacArthur Boulevard, Gibson said. By 10:30 p.m., the survey had received 35 reports from people who felt the quake. Most of the calls to emergency dispatchers were centered around the N.E. 29 Street and Martin Luther King Avenue area, Oklahoma City fire Deputy Chief Cecil Clay said.
Sharmaine McKee, who lives near N.E. 17 Street and Grand Boulevard, said she and her husband were watching television when the house shook. "It shook my whole bed, then the dogs started barking," McKee said. "It was something we'd never experienced." The episode lasted about 10 seconds.
Anyone who felt or heard the quake is asked to submit a report of their experience to the geological survey's Web site at www.okgeosurvey1.gov.
Cool, so Arkansas and OKC break off and sink into the earth, leaving NE OK an island state....beach front property!
several small earth quakes are a very good thing. Better than festering and waiting for one large(r) earth quake.
quote:
Originally posted by inteller
Cool, so Arkansas and OKC break off and sink into the earth, leaving NE OK an island state....beach front property!
and then...hurricanes.
quote:
Originally posted by Curmudgeon
quote:
Originally posted by inteller
Cool, so Arkansas and OKC break off and sink into the earth, leaving NE OK an island state....beach front property!
and then...hurricanes.
Golden Hurricanes...