- Signed: Matthew Hartman
- Filed under earthquakes , Indiana .
Why am I'm up so early this morning? This would explain why:
Yes, that would be a shake-map from the USGS. My sister called me at 5:00am this morning, telling me the shaking was so violent that it woke her up in Fishers, IN. Just from looking around at helicorders around the Midwest and Ohio Valley, this thing was felt across a fairly widespread area. Like I explained to my sister, there's a lot of solid ground in that part of the country and many, many shallow faults across the region. Preliminary reports are that this was a 5.4 on the Richter Scale. Quite strong for this part of the country!
Here are a couple of the helicorders I've looked at the past half-hour or so that are located near the epicenter.
This one, located near Olney, IL was likely the closest to the epicenter of the earthquake. As you can see, the quake, itself, lasted for a good 5-8 minutes (probably only about 5 minutes of shaking would have been felt, maybe even less, depending how shallow it occurred). Also, you may note several very small aftershocks after the main quake. You can see them on the traces, at the very end of the 4:45am trace and several others along the 5:00, 5:15, and 5:30am traces.
This one, located in Bloomington, IN doesn't show the quake lasting nearly as long and much less activity as far as aftershocks were concerned. A very weak one appears around 5:37am. The intensity here probably wasn't all much less than that near Olney. Obviously, P-waves (the deep, short wave-length, high amplitude waves that travel through Earth's crust) dampen with distance, but limestone is much more prevalent in southern Indiana, so the waves likely didn't dampen as much as you'd think. Bloomington isn't even maybe 50-70 miles away from the epicenter, so that's, obviously, a factor. The other type, by the way, S-waves (surface-waves) occur much shallower and on a longer wave-length.
Either way, a 5.4 quake along the IL/IN border is a fairly significant event. Likely nothing that would result in any major damage, but surely felt. As evidenced here. I even checked out some Helicorders around the upper Midwest - some in Minnesota that even picked up on the quake. Goes to show how far P and S-waves can travel!
Edit (6:30am CDT): It appears that the USGS has confirmed it as a 5.2 quake and a fairly shallow one, as I expected.
For more information...
Yes, that would be a shake-map from the USGS. My sister called me at 5:00am this morning, telling me the shaking was so violent that it woke her up in Fishers, IN. Just from looking around at helicorders around the Midwest and Ohio Valley, this thing was felt across a fairly widespread area. Like I explained to my sister, there's a lot of solid ground in that part of the country and many, many shallow faults across the region. Preliminary reports are that this was a 5.4 on the Richter Scale. Quite strong for this part of the country!Here are a couple of the helicorders I've looked at the past half-hour or so that are located near the epicenter.
This one, located near Olney, IL was likely the closest to the epicenter of the earthquake. As you can see, the quake, itself, lasted for a good 5-8 minutes (probably only about 5 minutes of shaking would have been felt, maybe even less, depending how shallow it occurred). Also, you may note several very small aftershocks after the main quake. You can see them on the traces, at the very end of the 4:45am trace and several others along the 5:00, 5:15, and 5:30am traces.
This one, located in Bloomington, IN doesn't show the quake lasting nearly as long and much less activity as far as aftershocks were concerned. A very weak one appears around 5:37am. The intensity here probably wasn't all much less than that near Olney. Obviously, P-waves (the deep, short wave-length, high amplitude waves that travel through Earth's crust) dampen with distance, but limestone is much more prevalent in southern Indiana, so the waves likely didn't dampen as much as you'd think. Bloomington isn't even maybe 50-70 miles away from the epicenter, so that's, obviously, a factor. The other type, by the way, S-waves (surface-waves) occur much shallower and on a longer wave-length.Either way, a 5.4 quake along the IL/IN border is a fairly significant event. Likely nothing that would result in any major damage, but surely felt. As evidenced here. I even checked out some Helicorders around the upper Midwest - some in Minnesota that even picked up on the quake. Goes to show how far P and S-waves can travel!
Edit (6:30am CDT): It appears that the USGS has confirmed it as a 5.2 quake and a fairly shallow one, as I expected.
For more information...
This entry was posted on Friday, April 18, 2008 and is filed under earthquakes , Indiana . Monitor this post through the RSS 2.0 feed. You may leave a comment, or trackback from your own site.
3 Comments
Anonymous
April 18, 2008 at 7:03 AM
Best coverage on the web as far as I have been able to find [thus far anyway].
Well Done!
-- C
Jim Kline
May 13, 2008 at 11:39 AM
I actually felt this quake (while still in bed)in my home in Northern Illinois. First thinking it was a nearby train, I soon realized (from the lack of any train horns or engine noise) that it wasn't. Early morning television news confirmed what I suspected.
Matthew Hartman
May 13, 2008 at 2:12 PM
Yeah, pretty rare to have that much earthquake activity that far north in the Wabash Valley. Quakes aren't that uncommon, but one on the size of the 5.2 shock and the number of aftershocks that accompanied it, is! Nice blog, by the way - I enjoyed the toilet paper vid. Funny!