Earthquake in US Midwest

[Broomstick]

Around 4:30/5:30 am local time (it straddled two times zones) the US Midwest experienced an earthquake, about 5.2 on the richter (sp?) scale. I happened to be up at the time, it woke up the Other Half, and all three of our birds which were screaming and thrashing in their cages. Not like prior quakes I've felt, which were a sort of shudder, but more of a swaying motion.

No damage here. Apparently some minor damage elsewhere. NOT New Madrid, but an intersecting fault, the Wabash.

[Coyote]

Earthquakes in the MidWest? Flatland country? That is bizarre. Nothing happens in the MidWest; nothing except sauerkraut and meth.

[Broomstick]

And, from CNN

People nearly 900 miles away felt a magnitude-5.2 earthquake that shook southern Illinois early Friday, according to the U.S. Geological Survey.

Rubble lies in the street Friday in Louisville, Kentucky, after part of a cornice fell off a building.

There were no immediate reports of major damage after the predawn quake, which struck at 4:36 a.m. (5:36 a.m. ET).

However, some minor damage was seen in the region.

Debris fell on a sidewalk and shattered in Louisville, Kentucky, after part of a cornice fell off a brick building, according to footage from the city's CNN affiliate WHAS-TV. Video Watch as the quake sends bricks tumbling »

The epicenter of the earthquake -- the strongest in the region in 40 years -- was about seven miles below ground and 38 miles north-northwest of Evansville, Indiana, the USGS said.

Nearly 10,000 people had sent reports of shaking to the USGS Web site by 9 a.m. ET.

People as far away as Niceville, Florida, 891 miles away, reported to the USGS Web site that they had felt the quake.

Reports also came in from such distant places as West Virginia, Alabama and Kansas.

"Pretty typically for these eastern-central U.S. earthquakes, they're felt over a very broad area," said Dave Applegate, USGS senior science adviser, adding that quakes in California tend to be more localized.

The Earth's crust is older and less fractured in the Midwest than in California, and the region's deep sediment "shakes a lot," Applegate said.

"Older crust, when you have an earthquake, it rings like a bell," he said.

The USGS said the largest historical earthquake in the region -- magnitude 5.4 -- shook southern Illinois in 1968.

I remember that one - my family was visiting the public library in University City, MO next to St. Louis at the time. At first we thought a big truck had gone by, but it went on lots longer than that, and gave everyone a pretty good shake. Got a little scary with the bookselves moving around, but no one got hurt where we were.

People as far away as southwest Michigan and northeast Georgia e-mailed CNN to say they felt Friday's tremor.

Air traffic was halted for an hour at Indianapolis International Airport while the control tower was evacuated, CNN affiliate WRTV-TV in the Indiana city reported.

And buildings swayed in Chicago's Loop, The Associated Press reported.

"It shook our house where it woke me up," David Behm of Philo, Illinois, told the AP. "Windows were rattling, and you could hear it. The house was shaking inches. For people in central Illinois, this is a big deal. It's not like California."

Radio talk-show host George Noory said he felt the quake in his St. Louis home.

"Everything shook," Noory said. "I thought the building was going to collapse." Video Watch as the talk-show host describes the early-morning shock »

Bonnie Lucas, who hosts a morning show at WHO-AM in Des Moines, told the AP she felt her chair move for five seconds.

The earthquake occurred in the Wabash Valley fault system, adjacent to the New Madrid Seismic Zone, Applegate said.

That zone, named for the town of New Madrid, Missouri, was the site of a series of huge tremors in 1811 and 1812

[Coyote]

Found it on MSNBC, too...

5.2 quake in Ill. shakes large part of Midwest
'This is a fairly large quake for this region,' USGS says


updated 37 minutes ago
WEST SALEM, Ill. - Residents across the Midwest were awakened Friday by a 5.2 magnitude earthquake that rattled skyscrapers in Chicago's Loop and homes in Cincinnati but appeared to cause no major injuries or damage.

The quake just before 4:37 a.m. was centered six miles from West Salem, Ill., and 66 miles from Evansville, Ind.

"It shook our house where it woke me up," said David Behm of Philo, 10 miles south of Champaign. "Windows were rattling, and you could hear it. The house was shaking inches. For people in central Illinois, this is a big deal. It's not like California."

Bonnie Lucas, a morning co-host at WHO-AM in Des Moines, said she was sitting in her office when she felt her chair move. She grabbed her desk, and then heard the ceiling panels start to creak. The shaking lasted about 5 seconds, she said.

The quake is believed to have involved the Wabash fault, a northern extension of the New Madrid fault about 6 miles north of Mt. Carmel, Ill., said United States Geological Survey geophysicist Randy Baldwin.

The last earthquake in the region to approach the severity of Friday's temblor was a 5.0 magnitude quake that shook a nearby area in 2002, Baldwin said.

[Broomstick]

Earthquakes in the MidWest? Flatland country? That is bizarre. Nothing happens in the MidWest; nothing except sauerkraut and meth.

Nonsense - the 1812 New Madrid quake rang church bells in Boston. The only reason it wasn't a historical disaster was that there were few people living in the Midwest at the time, and most of those in teepees and wigwams which, if they fall on you, are unlikely to kill you.

The problem with the Midwest quakes is that they tend to shake the solid interior of the continental plate, resulting in very widespread effects. Fortunately, most of the time, this is as strong as they get but every so often New Madrid really pops one off.

[Coyote]

So the possibility of developing some actual topography out there is still pretty low.

[Balrog]

It was centered in Illinois?

[Fundie]Obviously God is telling us not to vote for the secretly Muslim lie-beral![/Fundie]

[Glocksman]

The epicenter was only about 40 miles from me, so I felt it but at first thought it was just a big truck going by outside.

I slept through the 10:15 AM aftershock.

[Masami von Weizegger]

Yeah, some people were pretty shook up about it here.

I... uh... slept right through it.

[Alan Bolte]

Apparently it woke my mother up. I slept through it.

[Executor32]

I felt it. Until I read the news, I thought someone fell upstairs or something.

[Mr Bean]

Only 200 miles away, had no idea anything had happened.

[Warsie]

I felt it, felt a rumbling and vibrating in the bed, didn't give enough of a fuck to inquire too much. When I found out it was an earthquake I thought the New Madrid fault finally went...surprised it wasn't that fault

[Jadeite]

It woke me up here in West Lafayette, Indiana. In my half conscious state, I assumed that my apartment building was simply shaking from wind, thought "Wow, it must have been built by the lowest bidder" and then went back to sleep. I forgot about it until my professor in my first class brought it up.

The aftershock wasn't really a big deal either, just a little vibration that didn't last very long. In a way, the entire experience is sort of fun. My only worry is that my grandmother who lives in southern Indiana may have had a bunch of antiques broken. She's one of those people who places easily breakable items on high shelves.

[The Yosemite Bear]

isn't the Mississippi river a fault line?

[Broomstick]

Not the whole length of it, no, but it does follow New Madrid down by southern Missouri/Illinois

[Shroom Man 777]

I heard that earthquakes once caused the Mississippi River to flow backwards!

It is odd to hear of an earthquake in the US heartland. And every time I hear of earthquakes, especially in unusual places, a little bit of my idiot brain is reminded of those doomsday fundies and is subsequently frightened, just a little bit. I mean, with the whole world looking like its going to hell... (admittedly, the world always looks like its going to hell).

[Broomstick]

I heard that earthquakes once caused the Mississippi River to flow backwards!

Yes, that has happened. Only temporarily, of course, but still..

[Oni Koneko Damien]

Southern Wisconsin here, apparently it woke up the girlthing, but I was already awake and apparently too absorbed in whatever I was doing to notice it.

[Havok]

So has anyone from the SF Bay Area called you midwesterners sissies yet? No?

Sissies.

I remember reading or hearing that quakes around those parts have a "harder jolt" because of the granite? in and around the area?

[Oni Koneko Damien]

So has anyone from the SF Bay Area called you midwesterners sissies yet? No?

Sissies.

Hey, I spent six years just outside Reno, dealing with the aftershocks from your wussy Pacific jolts. I think the only reason I didn't feel anything when it actually happened was because it simply wasn't strong enough to attract my attention.

And if you ever get half your town destroyed by tornadoes two days after several water mains froze and split from ice-storms, just remember that you called the people who have to deal with that kind of thing basically yearly, wusses.

[Broomstick]

Not harder exactly but different. The geology on the west coast is jumbled and broken. It's two crustral plates, one diving under the other, along with broken fragments of same. Because it's not a solid, continuous sheet vibrations don't travel particularly far. Also, a lot of the rock is of a different chemistry and composition than in the center of a continental plate.

The New Madrid and associated faults (including the Wabash) aren't faults like, say, the San Andreas or the Pacific Ring of Fire meeting of plates. The New Madrid is sometimes called a "failed fault" - it's a big, long crack in the center of the continental plate itself, but it never finished splitting the North American plate. There are no plates riding up or under each other, and it's not two plates sliding past each other, either. The Pacific Ring of Fire is like a dinner plate with chips and fractures all around the edges. The New Madrid is like a big crack running through the center of a platter. The surrounding rock is entirely continental crust, not a mix of continental and ocean basalt. Continental crust is lighter/less dense, but it is also in some ways more brittle. Mid-plate faults such as New Madrid are not as common as subduction zone and plate boundary faults and are less understood.

Historically, the New Madrid zones give many minor tremors and every couple of decades one like the one we had this week, 4-5 on the rictcher scale. One in a great while, though, it pops off a really big one. The thing is, in California the jumbled geology will tend to interfere with earthquake vibrations. In the Midwest, there isn't really anything to stop the vibrations and they travel much farther distances. So, even a quake that is not so strong as those known along the West Coast has the potential to cause damage over a much wider area than would be the case in Los Angeles or San Francisco. The 1812 New Madrid quake was 7.9-8.0, so it was greater than the 1906 San Francisco quake which is usually given as 7.7 and it shook the ground over a MUCH larger area.

Because of this, modern skyscrapers in downtown Chicago are required to be designed to hold up to earthquakes, and that is also the case in St. Louis. I don't believe smaller and residential buildings are held to the same standards as they would be in California. A major New Madrid quake would likely result is a large number of dead and injured over hundreds, if not thousands, of kilometers in Illinois, Indiana, Kentucky, Tennessee, and Arkansas, with damage occurring even outside those states.