Posted on 12/16/2009 11:45:57 PM PST by ApplegateRanch
EVENTS IN NEBRASKA: "At 9 p.m. Central Time on Dec. 16th, a very bright meteor lit up the completely overcast sky like lightning in southeast Nebraska," reports Trooper Jerry Chab of the Nebraska State Patrol. "It flashed for approximately 2 seconds and was followed by ground shaking, which prompted many calls by the public to law enforcement in a three county wide area." The USGS says there was a magnitude 3.5 earthquake near Auburn, Nebraska, at 8:53 pm Wednesday night, about the same time and place as the fireball. Coincidence? Readers in Nebraska with photos or eyewitness accounts are encouraged to submit a report.
Large meteor? Space junk?
ping!
3.5 3 km ( 2 mi) NNW of Auburn, NE
http://earthquake.usgs.gov/earthquakes/recenteqsus/Quakes/quakes_big.php
“
Fireball AND a 3.5 earhtquake at the same time TONIGHT in south eastern Nebraska.
“
Arrival of some more hot recruits for the Cornhuskers?
(just jokin’...hope nobody was hurt...)
Don’t know yet, but it might be a small asteroid—lots of them in the past year or so, it seems; or maybe an especially large Geminid straggler.
At least we know the earthquake wasn’t caused by an impact—SE Nebraska is still intact. LOL
Glad everything's intact.
I've felt "impact earthquakes" before. They're no fun. ;-)
No, we’re in SW South Dakota, so far removed. Used to live in California & Oregon, so have felt some pretty good shakes, but never an “impact earthquake”...though I have caused a few of those, usually involving my rear end and a weak tree branch. ;’)
LOL - the ones I've experienced have been the unscheduled, unannounced, (OK, maybe the C-RAM might have sounded a few seconds prior on some of 'em), real-deal, whiz-bang thing. You're just minding your own business when....
BOOM! {shake, rattle, rattle....}
Oh my, is Hillary running around in that yellow pants suit again??????
....hmmmmmm something the MSM will blame on the military...any bases close by?
There was a time when I wanted to go and get some of that Bravo-B excitement after so many boring, tiring range rotations. ...not any more. I seek blissful boredom and relish rest. ;-) Anyway, it’s interesting to keep an eye on Nebraska, to see if anything hit the ground there. We do like to watch the night skies here on the Rockies once in a while.
Earthquake could have happened with no physical contact. Just the shock waves hit the earth (think of the airburst of a MOAB, or Hiroshima). More(!) at the link. (And where do I sign up to get a research grant to study this rare event! Seriously - would be interesting and PERHAPS useful!?)
http://www.blackwellpublishing.com/products/journals/aag/AAG_February07/aag_48106.htm
The 1974 Bala earthquake
The article on The enigmatic Bala earthquake of 1974 (Musson 2006) is an important contribution to the study of a long-neglected geophysical phenomenon, and one that will be essential reading for anyone who is interested in British seismology. However, the author appears to perpetuate some misunderstandings of meteoric processes, which ought to be corrected.
Musson states that the event is still listed as a possible impact event in Stratford’s (2004) catalogue, and says that a magnitude of 3.5 and 4.0 ML would be equivalent to a blast between some hundred tons of TNT and a small nuclear weapon (~4 × 1011 to 4 × 1013 J), and such an impact could not but leave a significant crater. In fact, the Berwyn Mountains explosion is listed in a table of Historical fireballs (not impacts) in Britain. More importantly, the work of Sekanina (1983), Chyba et al. (1993) and Hills and Goda (1993) has shown that large chondritic meteoroids entering the Earth’s atmosphere at interplanetary speeds are subject to aerodynamic pressures that exceed their mechanical strength and cause them to break up or even explode. The meteoroid in effect creates a transient crater in the atmosphere. The kinetic energy of the meteoroid is transferred to the atmosphere, and the longitudinal waves from the explosion can reach the Earth’s surface and shake buildings just as P-waves and S-waves from a seismic focus propagate upwards to the Earth’s surface. There is no need for any large meteorites to reach the ground to cause an observable earthquake.
There are many examples of earth tremors caused by the atmospheric explosion of large meteoroids. The Tunguska explosion of 30 June 1908 at h~ 8 km was recorded on seismographs in Irkutsk (about 1000 km from the focus of the explosion) and perhaps even as far away as Leningrad (St Petersburg), at r~ 3700 km (Verma 2005). The Chicora (Pennsylvania) fireball of 24 June 1938 was mistaken for the explosion of a magazine; the meteoroid is estimated to have had an initial mass m0~ 500 tonnes, but it yielded only two small meteorites, with a total mass of 303 g (Hey 1966). The great American fireball of 24 March 1933 caused terror across nine states, but the resulting Pasamonte (New Mexico) meteorite fall totalled only 34 kg (Hey 1966).
In Britain, the Chilterns fireball of 20 November 1887 was actually mistaken for an earthquake; tremors were felt from Saffron Walden and Cambridge to Wantage (Fordham 1888), and there was slight damage to buildings in Royston and mid-Bedfordshire. It being November, foggy weather prevented visual observations of the fireball along most of its path. The Welsh Borders fireball of 25 January 1894 caused earth tremors at Worcester and at Stokesay (10 km NW of Ludlow), and aroused fears of an explosion at Droitwich (Denning 1894). This fireball attracted the attention of Charles Fort, and as a result it is still occasionally mentioned in books about UFOs, earthlights, etc. Although Musson mentions that the shock wave from the Pontlyfni meteorite of 14 April 1931 was mistaken for an earthquake, he does not explain that Pontlyfni was the smallest meteorite known to have fallen in Britain, with m= 140 g, and that the earthquake was due to the atmospheric shock wave rather than the impact of the meteorite, which fell about 10 yards from a Mr Jones and caused no damage at all (King 1931). If Mr Jones had not been on the spot, the meteorite would not have been recovered, and the event might still be regarded as an earthquake or have been entirely forgotten.
Granted that exploding fireballs (airbursts) can produce seismic waves in the Earth’s crust, it should be possible to study these waves observationally and theoretically, both to distinguish them from the seismic waves produced by true earthquakes and to relate their properties to those of the airburst that caused them. It might contribute to the study of these airburst seismic waves if fireball observing stations were to include a seismograph as one of their instruments.
Fireball statistics suggest that airbursts with E > 1 kton TNT should occur over the British Isles on a timescale of about a century. In view of the arguments presented in this letter, it is worth considering what observable phenomena such an airburst would produce, in particular whether these phenomena could be mistaken for an earthquake. Unfortunately, the rarity of such large fireballs means that none has offered itself for study within the lifetime of advanced seismic arrays in Britain.
Uhh, Offut AFB is 50 miles north....
Thank you very much! I discounted any cause-effect, because of USGS listing it as occuring at a depth of 5 KM.
From your posting, though, that could be a false depth reading from preliminary data, without human anaysis?
:)
I live in se, nebraska, but I was at work at the time. We dont get earthquakes here, so It would be a hell of a coincidence.
I have to give you credit. Thats a good line.
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