OT: Increased Seismic Activity in AR Past Week

[FarPastGone]

Not a lot going on weather wise, so I thought this was interesting enough to post. Since 12PM Wednesday to around noon today the USGS has recorded nearly 50 earthquakes north of Little Rock in the Guy, AR area. The largest of which was a magnitude 4.0 earthquake at 8:30AM this morning (in terms of magnitude the lower 3.0 range is around the most minimal extent of noticing).

You can check out a map of the spatial extent of recent earthquakes in the Arkansas area here:

http://earthquake.usgs.gov/earthquakes/ ... 95.-85.php" onclick="window.open(this.href);return false;

It will zoom in on a specific area if you click on it, and you can check out a corresponding list of recent earthquakes in Arkansas here:

http://earthquake.usgs.gov/earthquakes/ ... 91_eqs.php" onclick="window.open(this.href);return false;

Some of the largest earthquakes in continental U.S. history occurred associated with the New Madrid Fault Zone in NE Arkansas.

- Matt

[Roger]

One of two possibilities are in this scenario.

1. The New Madrid is getting ready to go off since it has been over 200 years since it shook the earth along its fault lines and rang the bells in Boston, made the Mississippi run backward, and any other tales of the time.



http://www.ky3.com/news/kplr-a-new-stud ... 0623.story" onclick="window.open(this.href);return false;

2. It's due to the drilling and fracturing of geological formations that are called the Fayetteville Shale. Except it happens in areas where there is no known fault.

http://www.chron.com/disp/story.mpl/met ... 68271.html" onclick="window.open(this.href);return false;

Feel free to discuss and bring your data to the table.

[v rainwater]

Hey Matt,

Came over here to share this w/ you guys...48 in the last week aroud Guy.

http://m.thecabin.net/news/local/2010-1 ... ner-county" onclick="window.open(this.href);return false;

Vern

[DeBo]

Here is an interview Channel 7 did with a geologist:

http://www.katv.com/Global/category.asp?C=192879" onclick="window.open(this.href);return false;

[FarPastGone]

So I geeked out a bit and this is what I came up with…

I found a couple of different statistics but came to the consensus that the state of Arkansas averages between 150-200 earthquakes a year or about 3.28 earthquakes every six days in a 200 earthquake event year. Now earthquakes are not some equal interval phenomenon, for spare time statistics sake they are, but in this brief six day period of activity there were 49 earthquakes (I used 50 earthquakes) which would constitute a 1420% increase in 6-day period earthquake activity based on the annual average of 6-day period earthquake frequency.

I don’t think it necessarily means anything other than maybe the stress and strain of the inter-workings of the Earth were released in a number of minor seismic events, but than again I am just a nerdy kayaker so what do I know. Guy, AR is really close to Enola, AR famous for the Enola Swarm, an area that has seen similar high-frequency minor earthquake events, but is not associated with the New Madrid Seismic Zone. The initial event summaries from the USGS seem like stock synopses that attribute seismicity in Arkansas to the New Madrid, so it will be interesting to see the final analyses.

- Matt

[A Savage spanke]

Matt, you're my Randy Marsh.

Vern, your flags upside down.

-Ryan

[RandyJ]

Oklahoma joining in on the fun today. 4.5 mag quake near Norman, felt across most of the state, including here on the 19th floor of my office building. Now that's something different...

[FarPastGone]

The Oklahoma Geological Survey has upgraded it to a magnitude 5.1 earthquake, which would make it the second strongest quake in Oklahoma history, but there have been no changes to the initial USGS report of a 4.3 magnitude event yet.

http://earthquake.usgs.gov/earthquakes/ ... 10ciay.php" onclick="window.open(this.href);return false;

http://newsok.com/an-earthquake-shakes- ... le/3504094" onclick="window.open(this.href);return false;

Thanks Spanke, and on that note would you mind holding my beer for me this afternoon while I microwave two things.

- Matt

[A Savage spanke]

I think you're just going to have to break the law, even with cancer, Arkansas is not a "medicinal" state

[v rainwater]

A whole lota shakin goin on, a 4.4 this morning, biggest one yet.

Ryan, the upside down flag is a respectful distress call.

Vern

[v rainwater]

Here's a link I came across about a previously unknown fault in AR.

http://www.foxnews.com/story/0,2933,481388,00.html" onclick="window.open(this.href);return false;

[FarPastGone]

Yeah, I have heard a little bit about that, I know that the University of Memphis is donig a lot of earthquake related research in the region. The theory I have heard is that they are remnants of where the active zones in the region used to be. Guy is pretty central Arkansas (just like Enola), so maybe they are part of a fault zone that is not known or unexplored.

Just a side note, the USGS downgraded the earlier quake to a 3.8 magnitude, so the 4.0 quake on Monday was still more significant.

- Matt

[v rainwater]

Interesting discussion at GLP about a possible volcano in AR. This was the first I've heard about 'Hells half acre"...innerestin stuff.

http://www.godlikeproductions.com/forum ... 223088/pg1" onclick="window.open(this.href);return false;

[FarPastGone]

I can assure you that Crowley's Ridge is not the "ridge to the caldera", and from my understanding is a depositional feature (eolian not aluvial though) associated with the routing of melt-water from the Laurentide Ice Sheet down the Mississippi River (during a period when the St. Lawrence River was blocked). I honestly cannot speak to the other specific features he identifies since I am not a geologist, but you have to remember that the current landscape and geological profiles are the result of millions and millions of years of formational and weathering processes that may not be indicative of present day underlying regional mechanisms at work (just because you have igneous rock at some point in an areas geological history does not mean that area is volcanicly active).

I am sure there are plenty of others that can speak to the specific geology of the areas he identifies, whether it is a possibility or not, the way he presents his theory; by tying together a bunch of supposedly supportive geologic features from all around a geologically diverse state to answer unexplained earthquake activity through an unidentified volcano is completely false.

Hell's Half Acre looks cool though.

- Matt

PS…Reading that thread I was losing hope for humanity as more and more people hung on every word that dude had to say, but it has been slightly restored in the final few posts of the thread.

[GN YAKN]

Photo of earthquake damage in Okrahoma last week: