Posted on 03/12/2005 8:52:20 PM PST by bd476
For more information, go to http://neic.usgs.gov/ || Contacts
The official magnitude for this earthquake is indicated at the top of this page. This was the best available estimate of the earthquake's size, at the time that this page was created. Other magnitudes associated with web pages linked from here are those determined at various times following the earthquake with different types of seismic data. Although, given the data used, they are legitimate estimates of magnitude, they are not considered the official magnitude.
FAQ about Earthquakes | Earthquake Preparedness
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1) This was too big to be a nuke unless it was the largest of thermonuclear weapons (of a size even the US no longer has in its arsenal).
2) It was 35 miles deep. Can't be a nuke.
3) Nuclear explosions and quakes, even of the same magnitude, are INSTANTLY and easily distinguished on all seismographs. NEIC wouldn't have listed it as an earthquake otherwise.
Q: Can nuclear explosions cause earthquakes?
A: On January 19, 1968, a thermonuclear test, codenamed Faultless, took place in the Central Nevada Supplemental Test Area. The codename turned out to be a poor choice of words because a fresh fault rupture some 1200 meters long was produced. Seismographic records showed that the seismic waves produced by the fault movement were much less energetic than those produced directly by the nuclear explosion.
Analysis of local seismic recordings (within a couple of miles) of nuclear tests at the Nevada Test Site shows that some tectonic stress is released simultaneously with the explosion. Analysis of the seismic wavefield generated by the blast shows the source can be characterized as 70-80 percent dilational (explosive-like) and 20-30 percent deviatoric (earthquake-like).
The rock in the vicinity of the thermonuclear device is shattered by the passage of the explosions shock wave. This releases the elastic strain energy that was stored in the rock and adds an earthquake-like component to the seismic wavefield. The possibility of large Nevada Test Site nuclear explosions triggering damaging earthquakes in California was publicly raised in 1969.
As a test of this possibility, rate of earthquake occurrence in northern California (magnitude 3.5 and larger) and the known times of the six largest thermonuclear tests (1965-1969) were plotted and it was obvious that no peaks in the seismicity occur at the times of the explosions. This is in agreement with theoretical calculations that transient strain from underground thermonuclear explosions is not sufficiently large to trigger fault rupture at distances beyond a few tens of kilometers from the shot point.
The Indian and Pakastani test sites are approximately 1000 km from the recent Afghanistan earthquake epicenter. The question that has been asked is whether or not the occurrence of these nuclear tests influenced the occurrence of the large earthquake in Afghanistan.
The most direct cause-effect relationship is that the passage of the seismic waves, generated by the thermonuclear explosion, through the epicentral region in Afghanistan somehow triggered the earthquake.
For example, following the occurrence of the magnitude 7.3 Landers earthquake in southern California on June 28, 1992, the rate of seismicity in several seismically active regions in the western US, as far as 1250 km from the epicenter, abruptly increased coincident with the passage of the earthquake generated seismic wavefield through each site.
The abrupt increases in seismicity occurred primarily in regions of geothermal activity and recent volcanism. The mechanism by which this occurred remains unknown.
The Afghanistan earthquake occurred at 06:22:28 UT on May 30, 1998 and the thermonuclear test most closely associated in time occurred at 06:55 UT or after the occurrence of the earthquake. The other nuclear tests occurred 2-20 days before the earthquake.
The elastic strains induced in the epicentral region by the passage of the seismic wavefield generated by the largest of the nuclear tests, the May 11 Indian test with an estimated yield of 40 kilotons, is about 100 times smaller than the strains induced by the Earth's semi-diurnal (12 hour) tides that are produced by the gravitational fields of the Moon and the Sun.
If small nuclear tests could trigger an earthquake at a distance of 1000 km, equivalent-sized earthquakes, which occur globally at a rate of several per day, would also be expected to trigger earthquakes. No such triggering has been observed. Thus there is no evidence of a causal connection between the nuclear testing and the large earthquake in Afghanistan and it is pure coincidence that they occurred near in time and location.
One last point. The largest underground thermonuclear tests conducted by the US were detonated in Amchitka at the western end of the Aleutian Islands and the largest of these was the 5 megaton codename Cannikin test which occurred on November 6, 1971. Cannikin had a body wave magnitude of 6.9 and it did not trigger any earthquakes in the seismically active Aleutian Islands.
Suggested reading: "Nuclear Explosions and Earthquake, the Parted Veil", by Bruce A. Bolt, W. H. Freeman and Co., San Francisco, 1976.
(UC Berkeley)
Nuclear Explosions and Seismology
Here it is, although it's too detailed and large to print for comparison here on Free Republic. A link to an interactive version follows below:
USGS MAPS SHOWING GEOLOGY, OIL AND GAS FIELDS AND GEOLOGIC PROVINCES OF IRAN
Just thought I would get this down somewhere.
The last 24hrs the 2 out of 3 labs have been non stop coming up to me the baby whining and whining.
I have checked food, water ect...what are they trying to tell me?
They are very antsy about something.
I have put in quite a few round the clock hrs here caring for KV and we both have been pretty wiped out this week end sleepin to get our energy back, but that has happen before and the boys are usually just happy to have me up and I spend time giving hugs or if I sleep more then four hrs they will nudge me that is normal.
I leave the door open so they have plenty of property to run around on so I can't think of why so ANTSY.
The baby keeps whining and just stares me in the eye, I say "GO HUNT" means lets play retreive and he's like no stupid I am trying tell you something.
Perhaps they want me to go outside with them and hang out, I can't think of anything else.
Anyone else up here in the PNW having unsatisfied pacey doggie activity?
Wow that is deep.
I can't remember is it the closer to surface means more "felt"?
I know I asked last week but don't remember the answer.
Are you sure this isn't Bush's "fault"?
During times of drought, wild animals often make their way from the brush closer to civilized areas looking for food. Your neighbor's small dog or cat would make a perfect snack for a bobcat, small cougar, bear, etc.
Meanwhile look at this lovely picture taken over Puget Sound, Washington in December 2004.
Atmospheric Optics Halo Over Seattle
"Sunset halo over Puget Sound, Washington State. Taken from Seattle by David Kugler 11th December '04. The diffuse inner edge and broadening could be caused by diffraction effects from very small ice crystals."
LOL!
The deeper the quake, for the most part, the less damage. Generally the closer to the surface, depending on the size of the quake and what kind it is, the more destructive.
"Nuclear explosions and quakes, even of the same magnitude, are INSTANTLY and easily distinguished on all seismographs."
Definitely NOT true.
The evaluation process cannot be done "instantly", is definitely not "easy", and definitely cannot be done on "all seismographs". In many cases, it is easy to classify as "definite earthquake", but classifying as "nuclear explosion" is much more difficult.
But at 55km deep, this isn't anything nuke related, right?
No, it is not nuclear related. The most advanced drilling techniques in the world don't come close to that depth.
lol
Or ?
Instead of the fat lady singing, the fat lady finally farted.
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