Re: Earthquakes And Nuclear Testing
Posted by EQF on November 25, 2003 at 18:38:52:

Hi Don,

I did a NEIC search for earthquakes from 1973 to the present which had magnitudes of 8 or greater. Here are the results.

1975 8.10 UKPAS
1976 8.20 UKBRK
1976 8.00 UKGS
1977 8.10 UKPAS
1977 8.00 UKPAS
1980 8.00 UKBRK
1985 8.10 Ms GS
1986 8.30 MsBRK
1989 8.20 Ms GS

1993 8.20 MsBRK
1994 8.20 MwGS
1994 8.30 MwHRV
1995 8.10 MsBRK
1995 8.00 MwGS
1995 8.00 MwHRV
1996 8.20 MwHRV
1998 8.80 MEGS
1998 8.30 MEGS
2000 8.30 MEGS
2000 8.00 MEGS
2000 8.20 Ms GS
2000 8.20 MsBRK
2001 8.00 Ms GS
2001 8.40 MwHRV
2001 8.00 Ms GS
2002 8.50 Ms GS
2003 8.30 MwHRV

Between 1973 and 1993, 20 years, there were 9 of those earthquakes.

Between 1993 and the latest day in that data table, 10 years, there were 18 of those earthquakes.

Additionally, the highest magnitude one in that first period was an 8.3 magnitude one. In the second period there were 7 with an 8.3 magnitude or greater.

If the magnitudes of those earthquakes are on the same relative scale then I believe that those would be impressive statistics. However I do not know if the different magnitude measurement codes mean that the magnitude numbers are not actually good relative values. With one scale an 8 magnitude might mean one thing and then mean something else with a different measurement code.

Our local experts on such matters can express an opinion on that.

If those are good relative numbers then it means that there has to be an explanation for why those really powerful earthquakes in the first group occurred at only about 25% of the rate in the second group and why there were none above 8.3 magnitude in the first group.

The fact that the high yield nuclear tests ended in 1992 looks to me like a good possible explanation for statistics like that.

Here is another link which lists nuclear test dates:

http://www.okgeosurvey1.gov/level2/nuke.cat.html

The following is what I think might have happened assuming those statistics were valid. And there appear to be numerous Web sites which discuss this subject matter.

Strain gradually builds in a fault zone until the earthquake occurs. However if a fault zone is headed for a 8.5 magnitude earthquake and a shockwave from another earthquake or a nuclear test hits it at the right time and at the right angle months or years before the normal occurrence date then it could weaken the fault zone. And the earthquake might occur with a magnitude of 7.9 for example instead of 8.5.

There were so many nuclear tests during the decades before 1993 that they literally shook fault zones around the world to pieces. There was never a chance for any of them to accumulate enough strain energy for one of those really powerful earthquakes.

Remember, this is just a theory. I am not stating that I know that this is actually what happened.

Follow Ups:
     ● Re: Earthquakes And Nuclear Testing - Don in Hollister  20:05:29 - 11/25/2003  (20278)  (2)
        ● energy in earthquakes vs explosions - John Vidale  07:07:32 - 11/26/2003  (20283)  (1)
           ● Re: energy in earthquakes vs explosions - Don in Hollister  11:45:41 - 11/26/2003  (20284)  (0)
        ● Re: Earthquakes And Nuclear Testing - EQF  21:04:48 - 11/25/2003  (20279)  (1)
           ● Re: Earthquakes And Nuclear Testing - Don in Hollister  21:40:58 - 11/25/2003  (20280)  (1)
              ● where did 1,185,921 come from? - chris in suburbia  13:34:10 - 11/26/2003  (20285)  (1)
                 ● Re: where did 1,185,921 come from? - Don in Hollister  14:52:14 - 11/26/2003  (20286)  (0)