Another largish Midwest aftershock (just now)

USGS ^ | April 22, 2008 | USGS

[kc8ukw]

Magnitude 4.5 Date-Time

* Monday, April 21, 2008 at 05:38:30 UTC * Monday, April 21, 2008 at 12:38:30 AM at epicenter

Location 38.473°N, 87.823°W Depth 10 km (6.2 miles) set by location program Region ILLINOIS Distances

* 8 km (5 miles) NW (323°) from Mount Carmel, IL * 12 km (7 miles) WSW (238°) from Allendale, IL * 12 km (8 miles) NE (37°) from Bellmont, IL * 35 km (22 miles) SW (230°) from Vincennes, IN * 60 km (37 miles) NNW (337°) from Evansville, IN * 211 km (131 miles) E (94°) from St. Louis, MO

Location Uncertainty horizontal +/- 6.1 km (3.8 miles); depth fixed by location program Parameters NST= 44, Nph= 44, Dmin=37.6 km, Rmss=1.27 sec, Gp= 47°, M-type="Nuttli" surface wave magnitude (MLg), Version=7 Source

* U.S. Geological Survey, National Earthquake Information Center: World Data Center for Seismology, Denver

Event ID us2008rcar

[aruanan]

There was a quake in this region maybe 7 years ago.

[FunkyZero]

normally lots of small ones like this are a good thing. it doesn’t all relase at once

[SatinDoll]

Hey! You should get under the dining or kitchen table. Don’t sit there in a chair saying, “did you feel that, sweetie?”

Of course, I’ve been through dozens of earthquakes and one volcanoe eruption - California, Oregon, Spain, Mt. St.Helens, Washington. The New Madrid earthquakes of 1811-1812, they were much more serious and almost continuous nonstop rocking and rolling.

Be carefull, Grammy!

[SatinDoll]

Being in a power plant is probably one of the safest places you could be in an earthquake. Those babies are built to withstand vibration.

[Thermalseeker]

Nothing as far as I know is built to Earthquake code.

Some things are, but most doesn't appear to be up to a real shaker.

If you look at the bridges and overpasses along I-40 in the vicinity of Memphis, TN, you'll see cable restraints that have been installed between the bridge abutments and the spanning girders to reduce the chance that the bridges will shake apart and collapse during a major quake. Other than that, though, there aren't many visible signs I've seen of any earthquake code being followed like what you see in So. Cal.....

[Grammy]

"Of course, I’ve been through dozens of earthquakes and one volcanoe eruption - California, Oregon, Spain, Mt. St.Helens, Washington..."

More excitement in your life than I care to see. 8-) My sister lives in California, so this is nothing to her. I prefer tornadoes to earthquakes.

[Wordkraft]

I’m in Terre Haute, IN and I honestly haven’t felt even one shock. I lived in San Francisco for 25 years and I think my body is conditioned to not notice anything less than a 6.0 quake.

[RightWhale]

5.0 and up is reportable. Below is not worthy of a thread.

[RightWhale]

when you’re not in earthquake country.

It is earthquake country.

[stlnative]

This quake was downgraded to a 4.0.
I knew it felt weaker than a 4.5, because of the 4.6 I felt the other day.

[ravingnutter]

I’m in TX, we get every other disaster besides earthquakes, so I don’t understand.

Actually, we get earthquakes in Texas too, just not significant ones:

In historical times no earthquake with magnitude larger than about 6 has occurred in Texas. However, seismographs near El Paso record small earthquakes with magnitude of 2 or smaller every few days. Nearly every year earthquakes large enough to be felt by ordinary citizens occur somewhere in Texas.

EARTHQUAKE FAQ: TEXAS EARTHQUAKES

In fact, we had one earlier this month:

Magnitude 3.9 SOUTHERN TEXAS Monday, April 07, 2008 at 09:51:13 UTC

[stlnative]

Scientists say Midwest quakes poorly understood
http://www.physorg.com/news127823426.html

[OeOeO]

Manhattan , (GULP). I learn something new everyday here. Thanks.

[OeOeO]

In Chicago in the late 80’s or Early 90s there were headline scares of an imminent New Madrid eruption. (It was the first time in my life I had heard of it.) Our company spent lotsa bucks reinforcing things like data tape racks. Chicago claims to have high building code standards
but nothing's proved til something happens,like the WTC.
Of course we sit on a giant bed of mud and sand like Mexico City,that may help.

[kc8ukw]

Ouch.

Can you criticize a thread like that 9 hours after posting?

I understand that you live in Alaska - perhaps you could pity us Midwesterners that like to insist the ground beneath us be stable. :) (And then when you post that it is 100 degrees in Fairbanks, I won't reply that only 110+ is thread worthy! :D).

[RightWhale]

The Mississippi has reversed course. Farms, including cattle and plows and barns were swallowed into the earth. That will be thread worthy when it happens again.

[DoughtyOne]

Thanks StLNative. I hadn’t realized there were two faults in the region. I appreciate the link.

The New Madrid fault zone when viewed from space looks very flat. Just to the north is a region that shows some hills or small mountains.

This has led me to wonder if that region wouldn’t be very suspectible to the liquifaction effect during a stong quake, what would lead to a high level of severe damage.

[21twelve]

Actualy, when the next big one happens here it will be a nightmare for millions - including Manhattan. (In the 1800’s chimneys toppled in Boston when the New Madrid fault let go!). The thick “softer” sedimentary rocks in the Midwest and East transmit the shock waves better than the “harder” rocks in California.

Plus, much of the oil and gas pipelines running from Texas and Louisiana up to the Northeast would be damaged. Plus bridges, rail lines, etc.

[DoughtyOne]

Here’s a geographic resource that can be used to reveal the area around the New Madrid fault.

Go to the site and start clicking around the bootheal of Missouri.

As you zoom in on the area, it will become evident what I was addressing in my post to you, mountainous areas with large areas of smooth sedimentary plains in between.

A geologist might be able to tell you why liquifaction might not be a danger on these plains, but it sure looks like that might be a problem to me.

http://www.shadedrelief.com/physical/

[stlnative]

it is a problem already

this site writes about it

http://www.showme.net/~fkeller/quake/liquefaction.htm