Earthquake in Midwest

[montg]

Earthquake in Illinois, what an experience! Some force you can't see is shaking your bed, your house, everything..really unnerving. First thing I checked on this morning was my stereo--it's unharmed

AP story: Rare earthquake shakes midwest

[Joe G]

It was enough to wake me up, though basically amounted to a gentle shaking of the house by the time it got to Lansing. Not like the one in the late 90's, where the cats freaked out and it sounded like someone dropped a 1000-pound safe to the floor.

[Chuck Nessa]

Slept through it in Chicago.

[jlhoots]

My daughter felt it in Louisville.

Other family in Milwaukee also slept through it.

Edited April 18, 2008 by jlhoots

[Jim Alfredson]

I did not feel anything, but perhaps that's because I was in the basement. My power went out for a brief second, which was not good considering I was messing with the mixes of the new organissimo tracks.

[rachel]

Pretty strong in Indy; I was holding onto the bed like I was on a raft. It was surreal; I was in such a deep sleep that it was disorienting. Initially I thought it was a thunderstorm. I went outside immediately expecting to see evidence of a storm, but it was peaceful, quiet, and the ducks were swimming about as if nothing had happened. I almost thought I dreamt it at that point.

Edited April 18, 2008 by rachel

[Jim Alfredson]

Come to think of it, I think I heard it more than felt it. We're used to having rumbles here since we're so close to Lansing's main power plant. It rumbles and grumbles all the time and shakes the house. I heard a weird sound, though, that sounded like thunder or somebody dragging a plastic waste container down the alley. I couldn't for the life of me figure out what it was because the skies were totally clear.

Hmmmm....

[ejp626]

I felt it since I was up -- the whole apartment went back and forth 2 or 3 times. At first, I thought it was the upstairs neighbor somehow shaking everything (not thinking so clearly at 4 am) then realized it was an earthquake. My wife slept through it and didn't notice anything.

[ghost of miles]

It woke me and my wife up--at first, coming out of sleep, I thought it was just a large construction truck passing by, then realized that it was an earthquake. Our windows rattled quite a bit and the house vibrated, but everything's OK down here. Kind of odd, since I'd just mentioned the New Madrid fault to my wife a week or two ago (this wasn't a New Madrid quake, however, but we're overdue for one).

[Dan Gould]

Kind of odd, since I'd just mentioned the New Madrid fault to my wife a week or two ago (this wasn't a New Madrid quake, however, but we're overdue for one).

I was going to say. I remember when I first heard of the New Madrid fault when I lived in St. Louis and how the brick construction of so many homes would be disastrous when that fault decides to slip because the vibrations essentially turn the bricks into liquid.

Meantime, did anyone see the news about the new prediction for a CA earthquake at least as bad as Northridge? Over the next 30 years, the odds were placed at 99%. So for most of us, there is virtually a guarantee that there will be another disastrous or near-disastrous quake in CA in our lifetimes.

[7/4]

Major quake almost inevitable for California

Mon Apr 14, 2008 5:07pm EDT

By Dan Whitcomb

LOS ANGELES (Reuters) - California will almost inevitably be struck by a major earthquake, and possibly a catastrophic quake, sometime in the next 30 years, scientists said on Monday in the most comprehensive geologic forecast for the state.

California faces a more than 99 percent chance of being hit by a magnitude 6.7 temblor -- the size of the 1994 Northridge quake -- in the next 30 years, according to a study using new data and analyzing earthquake probabilities across the state.

The analysis found a nearly 50 percent chance that California would be rocked by a magnitude 7.5 quake, which is capable of inflicting catastrophic damage if it is centered under a big city like Los Angeles or San Francisco.

"We can expect that we're going to get hammered by a big earthquake and we'd better be prepared," said Tom Jordan, director of the Southern California Earthquake Center at the University of Southern California.

"Magnitude 7.5, that's a really big earthquake," Jordan said. "If that were to hit on the San Andreas Fault it could be very destructive. You're talking about an earthquake that might span 200 miles of fault length and a displacement of 12 feet or more.

"If that were to take place in say, the Los Angeles region, then you would have a big problem," he said.

Jordan said the chance of a 7.5 magnitude quake hitting Southern California was 37 percent, compared to 15 percent in Northern California, largely because the 1906 San Francisco earthquake relieved stress from the San Andreas Fault there.

The 1906 San Francisco quake was thought to have been a magnitude of around 7.8 or higher. The last temblor of that size in Southern California was in 1857, and the southernmost section of the San Andreas Fault has not seen such an event since 1680.

"Those faults have been accumulating stress all this time and that makes large earthquakes highly probable," Jordan said.

The January 17, 1994, Northridge quake in Los Angeles killed 72 people, injured more than 10,000 and caused billions of dollars in damage.

The study was conducted by the U.S. Geological Survey, the Southern California Earthquake Center and California Geological Survey and is significant because it presents the probabilities statewide for the first time.

"This is the most comprehensive earthquake forecast ever for the state of California," Jordan said, adding that it was requested by the California Earthquake Authority and would be used by the agency as a basis for

[7/4]

I remember when I was a kid - late '60s or '70s - I heard predictions that California was going to slide into the ocean.

I'm still waiting...

.

[BruceH]

Kind of odd, since I'd just mentioned the New Madrid fault to my wife a week or two ago (this wasn't a New Madrid quake, however, but we're overdue for one).

I was going to say. I remember when I first heard of the New Madrid fault when I lived in St. Louis and how the brick construction of so many homes would be disastrous when that fault decides to slip because the vibrations essentially turn the bricks into liquid.

Meantime, did anyone see the news about the new prediction for a CA earthquake at least as bad as Northridge? Over the next 30 years, the odds were placed at 99%. So for most of us, there is virtually a guarantee that there will be another disastrous or near-disastrous quake in CA in our lifetimes.

Time to move to North Dakota. (Seattle is also subject to earthquakes.)

[Free For All]

I'm currently in St. Louis, and I slept right through it. Not surprising for me, though......

[7/4]

This recent story was also interesting:

Swarm of earthquakes detected off Oregon Coast

ASSOCIATED PRESS

3:55 p.m. April 11, 2008

Scientists listening to underwater microphones have detected a swarm of earthquakes about 150 miles off the central Oregon Coast.

Geophysicist Robert Dziak (ZEE-ak) says they don't know what the earthquakes mean.

But he says they could be the result of magma rumbling underneath the Juan de Fuca Plate – away from the recognized earthquake faults off Oregon.

More than 600 quakes have been detected in the past 10 days. Three were of magnitude 5.0 or greater.

On the hydrophones, they sound like low rumbling thunder and are unlike anything scientists have heard in 17 years of listening.

Most are too small to be felt on shore.

Edited April 18, 2008 by 7/4

[BruceH]

This recent story was also interesting:

Swarm of earthquakes detected off Oregon Coast

ASSOCIATED PRESS

3:55 p.m. April 11, 2008

Scientists listening to underwater microphones have detected a swarm of earthquakes about 150 miles off the central Oregon Coast.

Geophysicist Robert Dziak (ZEE-ak) says they don't know what the earthquakes mean.

But he says they could be the result of magma rumbling underneath the Juan de Fuca Plate – away from the recognized earthquake faults off Oregon.

More than 600 quakes have been detected in the past 10 days. Three were of magnitude 5.0 or greater.

On the hydrophones, they sound like low rumbling thunder and are unlike anything scientists have heard in 17 years of listening.

Most are too small to be felt on shore.

This makes me very nervous.

[7/4]

This makes me very nervous.

I'm not too happy about it either, it could be the start of something like this:

[GregK]

I felt nothing in Dexter, MI. But there have been reports of people in Ann Arbor (7-8 miles east) who felt it

[Chuck Nessa]

I was spending the night at our daughter's place on the north side of Chicago. She said she was awakened by her cat running around the bedroom at the appointed time, but neither of us felt it.

[randissimo]

This recent story was also interesting:

Swarm of earthquakes detected off Oregon Coast

ASSOCIATED PRESS

3:55 p.m. April 11, 2008

Scientists listening to underwater microphones have detected a swarm of earthquakes about 150 miles off the central Oregon Coast.

Geophysicist Robert Dziak (ZEE-ak) says they don't know what the earthquakes mean.

But he says they could be the result of magma rumbling underneath the Juan de Fuca Plate – away from the recognized earthquake faults off Oregon.

More than 600 quakes have been detected in the past 10 days. Three were of magnitude 5.0 or greater.

On the hydrophones, they sound like low rumbling thunder and are unlike anything scientists have heard in 17 years of listening.

Most are too small to be felt on shore.

This makes me very nervous.

I lived in Oakland and was there during the 10/17/89 earthquake.. That's when I decided to move back to Michigan..

[7/4]

Scientists say Midwest quakes poorly understood

By DAVID MERCER, Associated Press WriterSat Apr 19, 9:56 AM ET

Scientists say they know far too little about Midwestern seismic zones like the one that rumbled to life under southern Illinois Friday morning, but some of what they do know is unnerving.

The fault zones beneath the Mississippi River Valley have produced some of the largest modern U.S. quakes east of the Rockies, a region covered with old buildings not built to withstand seismic activity.

And, when quakes happen, they're felt far and wide, their vibrations propagated over hundreds of miles of bedrock.

Friday's quake shook things up from Nebraska to Atlanta, rattling nerves but doing little damage and seriously hurting no one. It was a magnitude 5.2 temblor centered just outside West Salem in southeastern Illinois, a largely rural region of small towns that sit over the Wabash fault zone. The area has produced moderately strong quakes as recently as 2002.

But it hasn't been studied to nearly the degree of quake-prone areas west of the Rockies, particularly along the heavily scrutinized Pacific coast.

"We don't have as many opportunities as in California," said Genda Chen, associate professor of engineering at the University of Missouri-Rolla, which sits near the well-known and very active New Madrid fault zone.

"We cannot even borrow on the knowledge they learn on the West Coast" because quakes that happen in California — where tectonic plates beneath the Earth's surface collide — are so different from Midwestern quakes that happen far away from the edges of the nearest plates.

It isn't entirely clear, for instance, whether the Wabash faults are related to the New Madrid faults or not.

Some scientists say they are related, noting that the Wabash faults, which roughly parallel the river of the same name in southern Illinois and Indiana, are a northern extension of the New Madrid zone. Others say they're not.

The New Madrid fault zone produced a series of quakes in 1811 and 1812 that reached an estimated magnitude 7.0, putting them among the strongest known quakes to have occurred east of the Rockies. The quakes changed the course of the Mississippi River and were felt in New England.

That distance of well over a thousand miles sounds impressive, but experts say quakes that happen in the Midwest commonly radiate out for hundreds of miles because of the bedrock beneath much of the eastern United States.

"Our bedrock here is old, really rigid and sends those waves a long way," said Bob Bauer, a geologist with the Illinois State Geological Survey who works in Champaign.

He compared the underground rock, which in much of the Midwest lies anywhere from a few thousand feet to just a few feet below the earth's surface, to a bell that very efficiently transmits seismic waves like sound.

"California is young bedrock," he explained. "It's broken up ... like a cracked bell. You ring that, the waves don't go as far."

The question of whether Friday's quake was centered along a branch of the New Madrid zone or not is of more than academic interest. The area even now produces smaller, very regular quakes, and experts say it still has the potential to produce a quake that could devastate the region.

The Wabash faults have the potential to do the same, at least based on distant history, said Columbia University seismologist Won-Young Kim.

The strongest quake produced in recent history by the Wabash was a magnitude 5.3 in southern Illinois in 1968, but researchers have found evidence that 4,000 to 6,000 years ago, much stronger quakes shook the region, Kim said, as strong as magnitude 7.0 or more.

A similar quake is still possible, if the region is given time to build up enough energy, Kim said. But knowledge about the area is too thin to say whether that's likely, he added.

[7/4]

Magnitude-4.5 aftershock reported from Midwest earthquake

1 hour, 1 minute ago

A strong aftershock shook Southern Illinois on Monday, three days after a magnitude 5.2 quake rattled the region.

Geologists say the temblor just before 12:40 a.m. registered 4.5 magnitude at its epicenter about 5 miles northwest of Mount Carmel. The location is in the same area as Friday's early morning earthquake, which shook a wide area of the Midwest and caused minor damage.

The Monday morning aftershock was the 18th since Friday and the second strongest, according to the U.S. Geological Survey. The strongest was a 4.6 magnitude shaker about 5 1/2 hours after the original quake Friday morning.

[sheldonm]

...woke us up here in Indy...no damage. Felt the aftershock (one of several) as well a few hours later....crazy!

m

[BruceH]

You'd think being in Tornado Alley you'd be spared having to worry about earthquakes as well. Sheesh!