Arkansas cities feel unexplained surge in earthquakes

[Jolie Rouge]

Sarah Eddington, Associated Press – Thu Feb 17, 9:45 am ET

LITTLE ROCK, Ark. – Jim Sutterfield was briefly puzzled by a thumping sound that seemed to slam the back of his office chair. But when the small-town Arkansas fire chief turned and saw no one was around, he quickly realized it was just an earthquake — again. "That was only my second time to feel one, but others here have felt them for three or four months now," Greenbrier chief Jim Sutterfield said after feeling the latest tremor on Wednesday. "Now when it happens, people say, 'Well, there's another one.'"

Several small earthquakes ranging in magnitude from 1.8 to 3.8 have rattled the north-central Arkansas cities of Greenbrier and Guy this week, and the cause is unknown.

The U.S. Geological Survey has reported more than 30 earthquakes in the area since Sunday, including a magnitude 3.8 quake Thursday morning and at least 16 others occurring Wednesday, two of which were magnitude 3.2 and 3.5. More than 700 quakes have occurred in the region over the past six months.

Scott Ausbrooks, geohazards supervisor for the Arkansas Geological Survey, said the quakes are part of what is now called the Guy earthquake swarm — a series of mild earthquakes that have been occurring periodically since 2009. A similar swarm occurred in the early 1980s when a series of quakes hit Enola, Ark.

Ausbrooks said geologists are still trying to discover the exact cause of the recent seismic activity but have identified two possibilities. "It could just be a naturally occurring swarm like the Enola swarm, or it could be related to ongoing natural gas exploration in the area," he said.

A major source of natural gas in Arkansas is the Fayetteville Shale, an organically-rich rock formation in north-central Arkansas. Drillers free up the gas by using hydraulic fracturing or "fracking" — injecting pressurized water to create fractures deep in the ground.

Ausbrooks said geologists don't believe the production wells are the problem, but rather the injection wells that are used to dispose of "frack" water when it can no longer be re-used. The wastewater is pressurized and injected into the ground. "We see no correlation between natural gas production wells and earthquakes, but we haven't ruled out injection wells," he said, adding that if production wells were the cause, the earthquakes would be scattered all over the region underlain by the Fayetteville Shale formation and not in just one area.

Ausbrooks said the earthquakes are occurring in the vicinity of several injection wells.

Guy Police Chief Dave Martini said the locals continue to blame the gas companies for the quakes. "We have a disposal well here just outside of the city," Martini said. "People are suspecting that to be causing it, even though there isn't any proof of that."

Martini said the earthquakes started increasing in frequency over the past week and that the disposal well has seen an increase in use recently.

Lawrence Bengal, director of the Arkansas Oil and Gas Commission, said a six-month moratorium was established in January on new injection wells in the area. He said four companies are operating already-drilled injection wells: SEECO Inc., Chesapeake Operating Inc., Clarita Operating LLC and Deep-Six Water Disposal Services LLC.

The moratorium, which is expected to end in July, is intended to allow time to study the relationship — if any — between the injection wells and earthquakes in the area.

The largest quake of the Guy Earthquake Swarm was a magnitude 4.0, which occurred in October, Ausbrooks said. The region could possibly see quakes reaching as high as 5.0, but he said anything above 6.0 is unlikely.

The magnitude scale for earthquakes is logarithmic, meaning a magnitude 3 earthquake would produce waves with amplitudes 10 times greater than a magnitude 2 and 100 times greater than a magnitude 1. Geologists say quakes of magnitude 2.5 to 3.0 are generally the smallest felt by humans. "These periods of high activity are not uncommon. I don't think it's anything to be overly concerned about," Ausbrooks said. "We always encourage people to keep tuned in to what's going on and to always have an all-hazards disaster preparedness kit."

http://news.yahoo.com/s/ap/us_arkansas_earthquakes;_ylt=AkvkldNwJUjdQiKuDJt86 yWs0NUE;_ylu=X3oDMTNzZDQ2cjlwBGFzc2V0A2FwLzIwMTEwM jE3L3VzX2Fya2Fuc2FzX2VhcnRocXVha2VzBGNjb2RlA21vc3R wb3B1bGFyBGNwb3MDMTAEcG9zAzcEcHQDaG9tZV9jb2tlBHNlY wN5bl9oZWFkbGluZV9saXN0BHNsawNhcmtjaXRpZXNmZWU-

[Jolie Rouge]

Earth dodges geomagnetic storm
Jim Mannion – 1 hr 18 mins ago[/i]

WASHINGTON (AFP) – A wave of charged plasma particles from a huge solar eruption has glanced off the Earth's northern pole, lighting up auroras and disrupting some radio communications, a NASA scientist said. But the Earth appears to have escaped a widespread geomagnetic storm, with the effects confined to the northern latitudes, possibly reaching down into Norway and Canada. "There can be sporadic outages based on particular small-scale events," said Dean Persnell, project scientist at NASA's Solar Dynamics Observatory at Goddard Space Flight Center. He told AFP the official forecast is "for generally quiet conditions today, perhaps some minor storming tomorrow, but nothing extraordinary."

The event began Tuesday at 0156 GMT with a spectacular solar eruption in a sunspot the size of Jupiter that produced a Class X flash -- the most powerful of all solar events.

The eruption blasted a torrent of charged plasma particles called a coronal mass ejection (CME) toward Earth at about 560 miles per second (900 kilometers per second), the Solar Dynamics Observatory reported.

A direct hit from a CME could trigger a huge geomagnetic storm as incoming particles bounce off the Earth's geomagnetic field, blacking out radio communications, interfering with GPS navigational systems, in theory even causing power outages.

The China Meteorological Administration reported that the solar flare caused "sudden ionospheric disturbances" in the atmosphere above China and jammed shortwave radio communications in the southern part of the country.

Anticipating the worst, the US National Weather Service's Space Weather Prediction Service warned it was "the calm before the storm." "Three CMEs are enroute, all a part of the Radio Blackout events on February 13, 14, and 15 (UTC). The last of the three seems to be the fastest and may catch both of the forerunners about mid to late ... February 17."

But Persnell said the spiraling beam of solar particles from Tuesday's eruption was passing behind the Earth without making a direct hit. "In this case, it appears it will curve around and not hit us," he said.

He said satellite data "shows that the CME is quieting down and so there is not a whole lot left to it. So it's moved well behind us by now," he said.

But he said solar activity is on the upswing, and more CMEs will follow. "We are seeing more and more sunspots as what we call solar cycle 24 is turning on," he said. "At the peak we might see several of these CMEs a day coming off the sun. But they have only a five to ten percent chance of hitting us. We have to be in exactly the right place for that piece of spiral to come hit us. We'll see many more coming off the sun than we have hitting us here on Earth."

The British Geological Survey (BGS) said, meanwhile, that the solar storm would result in spectacular Northern Lights displays starting Thursday.

One CME reached Earth on February 14, "sparking Valentine's Day displays of the Northern Lights (aurora borealis) further south than usual."

The office published geomagnetic records dating back to the Victorian era which it hopes will help in planning for future storms. "Life increasingly depends on technologies that didn't exist when the magnetic recordings began," said Alan Thomson, BGS head of geomagnetism. Studying the records will tell us what we have to plan and prepare for to make sure systems can resist solar storms," he said.

A 2009 report by a panel of scientists assembled by NASA said that a sustained and powerful solar flare outbreak could overwhelm high-voltage transformers with electrical currents and short-circuit energy grids. The report, titled "Severe Space Weather Events -- Understanding Societal and Economic Impacts" warned that such a catastrophic event could cost the United States alone up to two trillion dollars in repairs in the first year -- and it could take up to 10 years to fully recover.

http://news.yahoo.com/s/afp/20110217/ts_alt_afp/usastronomytelecomnasachina

[MsLynn]

I used to work at the arkansas department of emergency management in conway.... most people would be amazed to know just how many earthquakes central arkansas actually has....

[iluvmybaby]

The New Madrid fault line runs under Arkansas, Illinois and I believe Missouri

[Jolie Rouge]

straight thru to New Orleans and to the Gulf.