Earthquake Details
Magnitude 5.4 (Preliminary magnitude — subject to revision)
Date-Time Friday, April 18, 2008 at 09:36:57 UTC
Friday, April 18, 2008 at 04:36:57 AM at epicenter
Location 38.501°N, 87.898°W
Depth 10 km (6.2 miles) set by location program
Region ILLINOIS
Distances 10 km (6 miles) ESE (103°) from West Salem, IL
10 km (6 miles) NE (55°) from Bone Gap, IL
13 km (8 miles) N (4°) from Bellmont, IL
39 km (24 miles) WSW (239°) from Vincennes, IN
66 km (41 miles) NNW (333°) from Evansville, IN
204 km (127 miles) E (93°) from St. Louis, MO
Location Uncertainty Error estimate not available
Parameters NST=021, Nph=021, Dmin=263.2 km, Rmss=1.07 sec, Gp=119°,
M-type=moment magnitude (Mw), Version=1
Source West Coast and Alaska Tsunami Warning Center/NOAA/NWS
Event ID at00851141
Illinois Earthquake [ 4.5 4/21 ]
Moderator: S2k Moderators
Illinois Earthquake [ 4.5 4/21 ]
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Re: Illinois Eathquake
Felt it here in St. Charles, MO. Worried me at first because I thought New Madrid had finally went. Glad that's not the case.
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flwxwatcher
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JonathanBelles
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This was the top news story in Detroit media. Why are more people not talking about this? It's historic, it doesn't happen very often and there were reports of people feeling it as far down as Florida!! I didn't feel it, I don't think it reached Ontario.
A 4.6 magnitude aftershock occurred I think at 11:14 am.
Link: http://earthquake.usgs.gov/eqcenter/eqi ... s2008qza6/
A 4.6 magnitude aftershock occurred I think at 11:14 am.
Link: http://earthquake.usgs.gov/eqcenter/eqi ... s2008qza6/
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Brent
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Re:
Cyclenall wrote:This was the top news story in Detroit media. Why are more people not talking about this? It's historic, it doesn't happen very often and there were reports of people feeling it as far down as Florida!! I didn't feel it, I don't think it reached Ontario.
A 4.6 magnitude aftershock occurred I think at 11:14 am.
Link: http://earthquake.usgs.gov/eqcenter/eqi ... s2008qza6/
Big story yeah but unless it causes death/destruction the national media is not going to cover it that much(though they have mentioned it).
Apparently it was felt in Atlanta and in some areas not far from here. Of course I was asleep.
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Re: Illinois Eathquake
Scientists: Even Bigger Quake Could Hit Midwest
The magnitude 5.2 earthquake that rocked the Midwest on Friday was felt from Kansas to Georgia.
Aftershocks could continue for months at this strange seismic zone at the nation's center and even trigger another big quake, a geophysicist said.
The quake occurred on a northern extension of the New Madrid fault, about 6 miles north of Mt. Carmel, Ill.
The New Madrid fault was responsible for devastating quakes in the Mississippi Valley in 1811 and 1812.
With that in mind, the Friday quake and its aftershocks may be raising the blood pressure of some residents and scientists.
For decades, scientists have debated whether and when the underlying fault could generate another temblor of similar and deadly strength.
"I think we saw a window to this possibility today in the Wabash Valley," said geophysicist Allessandro Forte of the Université du Québec à Montréal, who has studied the region's seismicity.
"It's to the north of the New Madrid seismic zone, but given the strength of crust, the stress can be distributed great distances," he said. "It's not clear if we could see something in the next few years or even next few months, I would say."
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, according to the U.S. Geological Survey.
An event actually surpassing today's magnitude last occurred in 1968, a magnitude 5.3 quake that was felt in 23 states and in Ontario and Boston, said Forte.
The magnitude scale is logarithmic so a change of 0.1 or 0.2 makes a big difference in terms of energy output.
"The $64,000 question is what this earthquake portends for the future," Forte said. "The answer is I'm afraid it can go either way."
Stress relief or hair trigger?
One scenario predicts that some stress is relieved on the local faults where this earthquake occurred and will cool things down for a few decades. The other scenario is not so happy.
"There is the possibility, and we can only see over next few months what will happen, that the redistribution of stress on neighboring faults might trigger further earthquakes, and we can only guess as to whether they'll be equally large as today's earthquake," Forte said.
Aftershocks from the Friday quake will continue for several weeks, maybe months, he said. Already, there have been many, of magnitudes in the range of 2 and 3, radiating outward from the epicenter.
"If we are seeing a propagation outward of stress changes after today's 5.2, which was a big one, and those stress changes finally come up on a fault which is on a hair trigger and ready to go, those small changes are sufficient to generate another big one on a fault which is locked and ready to go," Forte said.
How much risk?
Recent estimates have downgraded the risk of a large earthquake on the New Madrid fault.
In the 1980s, scientists said there was a 90 percent chance of a magnitude 6 or 7 temblor occurring in this area within the next 50 years.
A 2007 USGS fact sheet, however, said there is only a 25 percent to 40 percent chance of a magnitude 6 or larger there in the next 50 years.
However, a team that includes Michael Ellis of the University of Memphis estimated in 2005 that the odds of another 8.0 event in the region within 50 years are between 7 and 10 percent.
These debates about the New Madrid fault are far from resolved, Forte said, with some saying the accumulated stress in area faults is weakening while others say it is not going to dissipate any time soon.
"This is not exactly a well-defined science as yet," he said.
Forte is pessimistic, based on his research on an ancient, giant slab of Earth called the Farallon slab that started its descent under the West Coast 70 million years ago.
According to one theory, the Farallon slab is now is causing mayhem and deep mantle flow 360 miles beneath the Mississippi Valley, where it effectively pulls the crust down an entire kilometer (.62 miles).
[The other, not necessarily contradictory theory is that the lower Mississippi Valley is the site of a failed rift, a crack that appeared in the North American tectonic plate hundreds of millions of years ago and never fully healed.]
"The stresses from the sinking Farallon slab are not going to disappear any time soon," he said.
J. David Rogers agrees. The geological engineer at Missouri University of Science and Technology says Midwestern earthquakes are potentially more powerful than California quakes.
Shakier situation
Unique geology in the Midwest increases the shaking intensity of earthquakes because seismic energy moves through the dense bedrock at very high speeds, then becomes trapped in soft sediments filling river channels and valleys, Rogers said.
Rogers and some of his graduate students have been modeling synthetic seismic events in the New Madrid region.
Most of their scenarios are modeled after an 1895 earthquake with a magnitude of 6.4 that was centered in Charleston, Mo.
The preliminary results are sobering, said Rogers.
Data indicates ground shaking would be magnified about 600 percent within the flood plain of the Missouri River, a development that would cause most of Missouri’s existing long-span bridges to collapse.
"You don't even need a really big earthquake to do significant damage in Missouri," Rogers says. "It could happen tomorrow."
The relative quake risk of the New Madrid seismic zone is a great debate that might be driven in part by competition for grant money, Forte said.
Those scientists who work on West Coast quakes have an incentive to claim that the research money should be spent on that region, while the central continent-focused researchers obviously are more invested in funds coming their way.
Copyright © 2008 Imaginova Corp. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.
The magnitude 5.2 earthquake that rocked the Midwest on Friday was felt from Kansas to Georgia.
Aftershocks could continue for months at this strange seismic zone at the nation's center and even trigger another big quake, a geophysicist said.
The quake occurred on a northern extension of the New Madrid fault, about 6 miles north of Mt. Carmel, Ill.
The New Madrid fault was responsible for devastating quakes in the Mississippi Valley in 1811 and 1812.
With that in mind, the Friday quake and its aftershocks may be raising the blood pressure of some residents and scientists.
For decades, scientists have debated whether and when the underlying fault could generate another temblor of similar and deadly strength.
"I think we saw a window to this possibility today in the Wabash Valley," said geophysicist Allessandro Forte of the Université du Québec à Montréal, who has studied the region's seismicity.
"It's to the north of the New Madrid seismic zone, but given the strength of crust, the stress can be distributed great distances," he said. "It's not clear if we could see something in the next few years or even next few months, I would say."
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, according to the U.S. Geological Survey.
An event actually surpassing today's magnitude last occurred in 1968, a magnitude 5.3 quake that was felt in 23 states and in Ontario and Boston, said Forte.
The magnitude scale is logarithmic so a change of 0.1 or 0.2 makes a big difference in terms of energy output.
"The $64,000 question is what this earthquake portends for the future," Forte said. "The answer is I'm afraid it can go either way."
Stress relief or hair trigger?
One scenario predicts that some stress is relieved on the local faults where this earthquake occurred and will cool things down for a few decades. The other scenario is not so happy.
"There is the possibility, and we can only see over next few months what will happen, that the redistribution of stress on neighboring faults might trigger further earthquakes, and we can only guess as to whether they'll be equally large as today's earthquake," Forte said.
Aftershocks from the Friday quake will continue for several weeks, maybe months, he said. Already, there have been many, of magnitudes in the range of 2 and 3, radiating outward from the epicenter.
"If we are seeing a propagation outward of stress changes after today's 5.2, which was a big one, and those stress changes finally come up on a fault which is on a hair trigger and ready to go, those small changes are sufficient to generate another big one on a fault which is locked and ready to go," Forte said.
How much risk?
Recent estimates have downgraded the risk of a large earthquake on the New Madrid fault.
In the 1980s, scientists said there was a 90 percent chance of a magnitude 6 or 7 temblor occurring in this area within the next 50 years.
A 2007 USGS fact sheet, however, said there is only a 25 percent to 40 percent chance of a magnitude 6 or larger there in the next 50 years.
However, a team that includes Michael Ellis of the University of Memphis estimated in 2005 that the odds of another 8.0 event in the region within 50 years are between 7 and 10 percent.
These debates about the New Madrid fault are far from resolved, Forte said, with some saying the accumulated stress in area faults is weakening while others say it is not going to dissipate any time soon.
"This is not exactly a well-defined science as yet," he said.
Forte is pessimistic, based on his research on an ancient, giant slab of Earth called the Farallon slab that started its descent under the West Coast 70 million years ago.
According to one theory, the Farallon slab is now is causing mayhem and deep mantle flow 360 miles beneath the Mississippi Valley, where it effectively pulls the crust down an entire kilometer (.62 miles).
[The other, not necessarily contradictory theory is that the lower Mississippi Valley is the site of a failed rift, a crack that appeared in the North American tectonic plate hundreds of millions of years ago and never fully healed.]
"The stresses from the sinking Farallon slab are not going to disappear any time soon," he said.
J. David Rogers agrees. The geological engineer at Missouri University of Science and Technology says Midwestern earthquakes are potentially more powerful than California quakes.
Shakier situation
Unique geology in the Midwest increases the shaking intensity of earthquakes because seismic energy moves through the dense bedrock at very high speeds, then becomes trapped in soft sediments filling river channels and valleys, Rogers said.
Rogers and some of his graduate students have been modeling synthetic seismic events in the New Madrid region.
Most of their scenarios are modeled after an 1895 earthquake with a magnitude of 6.4 that was centered in Charleston, Mo.
The preliminary results are sobering, said Rogers.
Data indicates ground shaking would be magnified about 600 percent within the flood plain of the Missouri River, a development that would cause most of Missouri’s existing long-span bridges to collapse.
"You don't even need a really big earthquake to do significant damage in Missouri," Rogers says. "It could happen tomorrow."
The relative quake risk of the New Madrid seismic zone is a great debate that might be driven in part by competition for grant money, Forte said.
Those scientists who work on West Coast quakes have an incentive to claim that the research money should be spent on that region, while the central continent-focused researchers obviously are more invested in funds coming their way.
Copyright © 2008 Imaginova Corp. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.
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Miss Mary
Re: Illinois Earthquake
We didn't feel the earthquake! My 17 yo daughter said it's her first one and she slept right thru it. People all around the Cincinnati area felt the 5.2 quake but again, we kept sleeping! I do recall the dog barking in the middle of the night (around 2 or 3), as if there was a wild animal outside but I would have remembered it was 5:37 when she barked, b/c my alarm goes off at 5:45, I would have just stayed up! I think it was much earlier when she went nuts with barking (she sleeps inside). No injuries reported but people had wall pictures move and things topple over on furniture, etc.
I can't believe I didn't feel it! I'm such a light sleeper too......
A Univ. of Cincinnati professor recorded there was a 4.5 aftershock at 11:17 a.m. Here's a local article if anyone is interested:
http://news.enquirer.com/apps/pbcs.dll/ ... /804190367
My college aged daughter goes to Western Kentucky (Bowling Green) and they felt it. But she was home for the weekend (and missed it, like the rest of us, except maybe the dog! LOL)........When she's on campus, she's much closer to the New Madrid Fault Line (which worries me).
I can't believe I didn't feel it! I'm such a light sleeper too......
A Univ. of Cincinnati professor recorded there was a 4.5 aftershock at 11:17 a.m. Here's a local article if anyone is interested:
http://news.enquirer.com/apps/pbcs.dll/ ... /804190367
My college aged daughter goes to Western Kentucky (Bowling Green) and they felt it. But she was home for the weekend (and missed it, like the rest of us, except maybe the dog! LOL)........When she's on campus, she's much closer to the New Madrid Fault Line (which worries me).
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flwxwatcher
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Re: Re:
Brent wrote:Cyclenall wrote:This was the top news story in Detroit media. Why are more people not talking about this? It's historic, it doesn't happen very often and there were reports of people feeling it as far down as Florida!! I didn't feel it, I don't think it reached Ontario.
A 4.6 magnitude aftershock occurred I think at 11:14 am.
Link: http://earthquake.usgs.gov/eqcenter/eqi ... s2008qza6/
Big story yeah but unless it causes death/destruction the national media is not going to cover it that much(though they have mentioned it).
Apparently it was felt in Atlanta and in some areas not far from here. Of course I was asleep.
The media did give it some coverage but your right; the motto of the media pretty much is " if it bleeds, it leads"
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Re: Illinois Earthquake
Aaaaaaaand again! http://earthquake.usgs.gov/eqcenter/rec ... 08rcar.php
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Re: Illinois Earthquake
Beam wrote:Aaaaaaaand again! http://earthquake.usgs.gov/eqcenter/rec ... 08rcar.php
Magnitude-4.5 aftershock reported from Midwest earthquake
1 hour ago
WEST SALEM, Ill. (AP) — 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.
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mrslinarcos
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Re: Illinois Earthquake [ 4.5 4/21 ]
I live in Olney, IL and the mag. 5.4 was the first quake I had felt in years. I had been living in FL for 28 years; born and raised in Metropolis, IL. To me, there's no doubt about it, the Wabash Valley is in for a big one. And I left FL for this?? Oh well, but I know how important it is to be prepared. And I take this and all things like this seriously.
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Welcome to the forum!!! Great reading the first-hand experiences of a person that felt the quake.
Re: Illinois Earthquake [ 4.5 4/21 ]
Another earthquake in Illinois today.
Magnitude 3.1 - ILLINOIS
2008 July 18 02:58:55 UTC
Earthquake Details
Magnitude 3.1
Date-Time
* Friday, July 18, 2008 at 02:58:55 UTC
* Thursday, July 17, 2008 at 09:58:55 PM at epicenter
* Time of Earthquake in other Time Zones
Location 38.459°N, 87.841°W
Depth 10 km (6.2 miles) set by location program
Region ILLINOIS
Distances
* 8 km (5 miles) NW (308°) from Mount Carmel, IL
* 10 km (6 miles) NE (36°) from Bellmont, IL
* 12 km (8 miles) N (11°) from Keensburg, IL
* 59 km (37 miles) NNW (335°) from Evansville, IN
* 210 km (130 miles) E (94°) from St. Louis, MO
Location Uncertainty horizontal +/- 5 km (3.1 miles); depth fixed by location program
Parameters NST= 18, Nph= 18, Dmin=37.9 km, Rmss=0.63 sec, Gp= 76°,
M-type="Nuttli" surface wave magnitude (MLg), Version=8
Source
* USGS NEIC (WDCS-D)
Event ID us2008uqah
* This event has been reviewed by a seismologist.
Magnitude 3.1 - ILLINOIS
2008 July 18 02:58:55 UTC
Earthquake Details
Magnitude 3.1
Date-Time
* Friday, July 18, 2008 at 02:58:55 UTC
* Thursday, July 17, 2008 at 09:58:55 PM at epicenter
* Time of Earthquake in other Time Zones
Location 38.459°N, 87.841°W
Depth 10 km (6.2 miles) set by location program
Region ILLINOIS
Distances
* 8 km (5 miles) NW (308°) from Mount Carmel, IL
* 10 km (6 miles) NE (36°) from Bellmont, IL
* 12 km (8 miles) N (11°) from Keensburg, IL
* 59 km (37 miles) NNW (335°) from Evansville, IN
* 210 km (130 miles) E (94°) from St. Louis, MO
Location Uncertainty horizontal +/- 5 km (3.1 miles); depth fixed by location program
Parameters NST= 18, Nph= 18, Dmin=37.9 km, Rmss=0.63 sec, Gp= 76°,
M-type="Nuttli" surface wave magnitude (MLg), Version=8
Source
* USGS NEIC (WDCS-D)
Event ID us2008uqah
* This event has been reviewed by a seismologist.
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