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

[kc8ukw]

Just in case you're again wondering if your house is settling... a lot.

[kingu]

This is what happens when you vote for Huc... *cough* I mean, I hope everyone’s alright, that is a strong size when you’re not in earthquake country.

[MediaMole]

People keep saying they’ve felt these, but I never notice. (500+ miles away)

I just hope this isn’t a prelude to something really damaging.

[BurbankKarl]

Oh Yeah, the Yellowstone Caldera is about to let go.

[OeOeO]

I felt and thought I heard the one the other day, and I'm outside Chicago.It's so unusual you think it's your imagination.

We are actually pretty near earthquake country, St. Louis is almost on top of it. The New Madrid fault sparked 2 huge quakes in the 1800's when the area was relatively unpopulated. They altered the path of the Mississippi river. People here are going to get the shock of their lives one day. Nothing as far as I know is built to Earthquake code.

[Grammy]

Mr G felt the table shaking, and I heard a very low rumble when it happened. I immediately started looking on the internet to confirm it, and knew it would be here.

Not nearly as intense as the one Friday. That one woke us up from a dead sleep, and the bed shook pretty well for a while. This one we would have slept through.

[stlnative]

this lastest one will be downgraded. we had a 4.6 after the 5.2 and this one (4.5) was not as strong as the 4.6.
I’d guess it as a 4.0 to 4.2 tops

it only lasted about 20 seconds compared to the 45 seconds for the first two.

but believe me I am worried also that this may a build up of something larger in the days ahead.

[kc8ukw]

I immediately started looking on the internet

That's exactly what I did after the first one! For 15 minutes I wondered why there was no FR post... and never thought to turn the radio on. What has happened to me?

[stlnative]

latest (not lastest)

[stlnative]

bookmark this... it shows up here first and it was up within a few minutes of the quake.

http://earthquake.usgs.gov/eqcenter/recenteqsus/Maps/US2/37.39.-89.-87_eqs.php

[shineon]

I felt this one two. Just a little shaking, shifting, but it woke me up.

[Grammy]

I found the first one on Freerepublic an hour before they reported it on Fox! After it got me so wide awake there was no way to go back to sleep without finding out what happened.

[shineon]

whoops ... this one too.

[MEpajamaMONSTER]

I hate when that happens!

[stlnative]

I think most of us are on the edge due to it being so active right now. It is amazing how far it can be felt.

I know it broke several home water lines (from the meter to the house) in Marion IL after the 5.2

[Global2010]

Unusual.

Earthquake Ping.

[txflake]

Does.... this make the shakings y’all had.. foreshocks?

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

[stlnative]

well they could be foreshocks, but let’s hope not.

Go to the link I posted and you will see how active it has been. It had been quiet for quite some time before the 5.2 we had on 4/18.

The 5.2 made it feel like a large person fell into the side of the bed and then the shaking was lighter for about another 40 seconds. You can hear the house rattle at the same time you are feeling it.

It woke me up instantly and kicked the covers off and headed for bedroom door way. It was still going by time I was in the doorway.

[shineon]

What Are Aftershocks, Foreshocks and Earthquake Clusters?

The calculations in this system are based on known behaviors of aftershocks. Scientists have shown that the rules governing aftershock behavior also apply to "aftershocks" that are larger than their main shock - i.e., the possibility that the first event was a foreshock. These rules include:

Aftershock Facts: In a cluster, the earthquake with the largest magnitude is called the main shock; anything before it is a foreshock and anything after it is an aftershock. A main shock will be redefined as a foreshock if a subsequent event has a larger magnitude. The rate of main shocks after foreshocks follows the same patterns as aftershocks after main shocks. Aftershock sequences follow predictable patterns as a group, although the individual earthquakes are random and unpredictable. This pattern tells us that aftershocks decay with increasing time, increasing distance, and increasing magnitude. It is this average pattern that this system uses to make real-time predictions about the probability of ground shaking.

Distance: Aftershocks usually occur geographically near the main shock. The stress on the main shock's fault changes drastically during the main shock and that fault produces most of the aftershocks. Sometimes the change in stress caused by the main shock is great enough to trigger aftershocks on other, nearby faults, and for a very large main shock sometimes even farther away. As a rule of thumb, we call earthquakes aftershocks if they are at a distance from the main shock's fault no greater than the length of that fault. The automatic system keeps track of where aftershocks have occurred, and when enough aftershocks have been recorded to pinpoint the more and less active locations, the system adjusts the probabilities on the map to reflect those local variations.

(Click for image for a larger version)

Time: An earthquake large enough to cause damage will probably be followed by several felt aftershocks within the first hour. The rate of aftershocks decreases quickly - the decrease is proportional to the inverse of time since the main shock. This means the second day has about 1/2 the number of aftershocks of the first day and the tenth has about 1/10 the number of the first day. These patterns describe only the overall behavior of aftershocks; the actual times, numbers and locations of the aftershocks are random. We call an earthquake an aftershock as long as the rate at which earthquakes occur in that region is greater than the rate before the main shock. How long this lasts depends on the size of the main shock (bigger earthquakes have more aftershocks) and how active the region was before the main shock (if the region was seismically quiet before the main shock, the aftershocks continue above the previous rate for a longer time). Thus, an aftershock can occur weeks or decades after a main shock.

Magnitude: Bigger earthquakes have more and larger aftershocks. The bigger the main shock the bigger the largest aftershock will be, on average. The difference in magnitude between the main shock and largest aftershock ranges from 0.1 to 3 or more, but averages 1.2 (a M5.5 aftershock to a M6.7 main shock for example). There are more small aftershocks than large ones. Aftershocks of all magnitudes decrease at the same rate, but because the large aftershocks are already less frequent, the decay can be noticed more quickly. Large aftershocks can occur months or even years after the main shock.

[stlnative]

Aftershock Facts: In a cluster, the earthquake with the largest magnitude is called the main shock; anything before it is a foreshock and anything after it is an aftershock. A main shock will be redefined as a foreshock if a subsequent event has a larger magnitude

Let's hope the 5.2 stays as the main shock and not foreshock!

[stlnative]

where is your general location?

[stlnative]

Yet another quake, a 4.5, hits the region

http://www.southernillinoisan.com/articles/2008/04/21/breaking_news/doc480c30f043f35696552381.txt

[shineon]

Saint Charles, but I’ve been flying back to MA on the weekends.

[shineon]

That’s Saint Charles MO

[stlnative]

LOL... yeah there is a St. Charles IL. :-)

but I lived in St. Charles MO in the early 90’s

I am currently along the MO/IL border in Southwest IL just across from Perryville MO.

[DoughtyOne]

Anything in that general region makes me think of the New Madrid fault. I don’t like that prospect one bit.

[stlnative]

Another quake rumbled early this morning
ST. LOUIS POST-DISPATCH STAFF
04/21/2008

http://www.stltoday.com/stltoday/news/stories.nsf/stlouiscitycounty/story/2442CD6A48BAA07286257432000CC699?OpenDocument

[kingu]

Yeah, there’s a lot of places that are known earthquake areas (like Manhattan Island) that are not anywhere built to the standards of construction that would withstand a likely earthquake. Especially in the New Madrid Zone where buildings built after the last Madrid quake are made out of unreinforced brick.

If or rather when there’s another significant quake there, it won’t be a rude surprise, it’ll be a nightmare for the thousands who will find themselves in brick rubble.

[stlnative]

As you probably already know these quakes are coming from the Wabash Valley Zone but unfortunately the two faults are in line with each other.

This is a informative website about these 2 faults.
http://showme.net/~fkeller/quake/index.htm

[eastforker]

Have you lived there long SLN.I bet you and I know some of the same people. Heck I might even know you.

[flaglady47]

My sister and I both live in the Chicago suburbs. She was awakened by the quake. Said it shook her bed, and she knew immediately that it was probably a quake. I, on the other hand, slept right through it (I’m one town over from where she lives). Well, at least if a bigger one hits, and assuming I don’t get creamed by it, I’ll probably stay asleep and thus will remain calm as I will be asleep. Unless of course the quake hits during the day. Then I’ll rock and roll with the rest of the folks.

[stlnative]

We have talked before about the area.
I am a transplant here and it is possible that we both know some of the same folks. But you know how it is here if you are a transplant to the area.

[eastforker]

Oh yeah, I am sure you have been talked about, suspected as an undercover cop and lord knows what else.It’s a nice rural little town, however, lots of drugs move and made in that county. I could probably name key players.My mother and sister still live there but am glad I got out almost 40 years ago.

[stlnative]

Speaking of drugs... they just made a crack house bust right near the Randolph County Court House last week.

But really the drug problem is not that huge around here as it could be.

[eastforker]

It is much bigger than you might think. Yes it is under the wire, more dealers than users. The pot is grown amongst much of the farmers crops where it goes mostly undetected. Lots of old farm houses and barnes where it is processed after harvesting. Don’t get me started about the meth labs in the surrounding areas, made there and sold up north around St.L or down around Murphy and carbondale and Marion.

[familyop]

A large New Madrid quake is likely to be a whole different animal from the coastal quakes we’ve heard about. It’s possible that the quakes in December, 1811, January, 1812, and two February quakes (four large ones, as felt by people) were actually effects of one long disturbance. Effects felt as aftershocks really overlapped from the first perceived large quake until long after the last. Although the worst of the perceived and reported shocks is estimated to have been only 7.5 or so, there are other considerations (land elevations greatly and permanently changed, “sand blows,” strata different from coastal regions, etc.).

[Mustng959]

Interesting comment about the water lines. Supposedly the one the other day was felt here in Tennessee (I didn’t feel it). Last night at work, we had no water ... as well as the rest of the town for about 12 hours. Found out this morning that a main water line broke. Wondering now if there’s a connection?

[roadcat]

A few helpful tips on surviving after the big earthquake, from a native San Franciscan.

Have plenty of batteries, flashlights, candles and lanterns available. Power will most likely be out, probably for days. Our power was out for several days after the 1989 quake. It also helps to have a battery powered TV set, helped my family to find out what was going on. Upon evacuating from my jobsite in 1989, me and some co-workers came upon a guy with a portable TV in a parking lot. A lot of people were walking towards the Bay Bridge, but we learned from the TV that it was out.

So figure that lots of bridges may be closed. Probably would help to have maps on hand (and a portable GPS device). Also know where your family members will meet up. Communications will probably be down. I was lucky, as I was on the telephone with my wife as the quake hit, so I knew my family was alright. Also figure that it will take a long time to drive anywhere, as traffic lights will be out, and debris will be in the streets. I saw lots of glass and bricks from chimneys in the streets. Not to mention people walking in the street (afraid to be on the sidewalks).

Have cash on hand, as credit cards will be useless. Have an ice chest ready to go, stocked with survival items. You may have to leave your home if it's damaged. Hope this helps when the New Madrid fault lets go with the big one.

[stlnative]

I am hearing reports of many water line breaks (small & large water lines). I think there was a main break in St. Louis also. (some 128 miles away from the center of the 5.2 quake)

Marion IL is about midway point (about 64 miles) from the center of the quake.

Over the years all we hear about is the New Madrid fault in this area. But I am really starting to think the Wabash Valley fault is the one that we need to worry about as it has produced many 3.0 and over quakes since I moved to the area in 1994. (I have felt just about everyone of the 3.0 and over quakes from it and I am at least 125 miles away from it)

I am actually on the New Madrid fault and I never feel it moving even though it does move much more often than the Wabash.

I know after the 2002 Wabash small quake, my quake insurance went up quite a bit. I know now it is going to jump up probably much much more now.

Well I am tired, time to crash!

[freedom4ever]

I am, tonight, about 5 miles from the epicenter of these quakes and aftershocks. For the first one, the 5.2, I was home asleep, about 25 miles away from the epicenter. That was violent to me. Tonight I am at work, in a large powerplant on the In./ Il. border near Mt Carmel, Il. I am on the third floor in the control room. It was just a quick movement for us. We had spikes on vibration monitors on certain pieces of equipment when it hit and several of them came in alarm. We didn’t trip any equipment, though.

[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.