Expert: Small Ark. earthquakes could be warning

[Guest guest]

I have family out that way including a cousin I like.

I've been watching the quakes for the last few months on the USGS site. They are very tightly clustered together in one area. That has attracted my attention, so it is little wonder it has at least one expert wondering.

By all accounts, another 1812 scale event would wipe out a wide area because of the population density and that few buildings are strong to withstand it. The economic repercussions would be great because of all the industry and corporate headquarters in the area. In addition, fallen bridges would block the Mississippi River and it might even change course locally, meaning new channels would have to be dredged.

In a message dated 11/28/2008 6:19:29 P.M. Eastern Standard Time, no_reply writes:

Anyone here live in that region?AdministratorLife should be easier. So should your homepage. Try the NEW AOL.com.

[Guest guest]

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Expert: Small Ark. earthquakes could be warning

By JON GAMBRELL, Associated Press Writer J

on Gambrell, Associated Press Writer – Fri Nov 28, 5:51 am ET

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

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 nna 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. "

[Guest guest]

Anyone here live in that region?

Administrator

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Expert: Small Ark. earthquakes could be warning

[Guest guest]

" By all accounts, another 1812 scale event would wipe out a wide area

because of the population density and that few buildings are strong to

withstand it. The economic repercussions would be great because of all

the industry and corporate headquarters in the area. In addition,

fallen bridges would block the Mississippi River and it might even

change course locally, meaning new channels would have to be dredged. "

Experts have warned that the New Madrid is overdue for a large quake,

and I am wondering if all these little tremmors are really foreshocks.

These coupled with the ones we've had in Illinois these past few years

might be signalling something, although ther larger Illinois quakes are

said to be normal.

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