[Phys-L] Re: earthquake

[betwys1 at SBCGLOBAL.NET (Brian Whatcott)]

At 10:02 AM 12/30/2004, you wrote:
> The following quotation is from the Chicago Tribune on-line edition.
>
> * * * <quotation from Tom Skilling> * * *
> Incredibly, the magnitude 9.0 earthquake that struck off Sumatra on
> Sunday morning caused a vertical displacement of so much material that
> the rotation period of the Earth has been permanently altered. By a tiny
> but measurable amount, the Earth is now rotating more quickly on its
> axis, and the 24-hour day is now one ten-thousandth second
> shorter.That's the result of calculations based on preliminary data made
> by Oak Park astronomer Dr. Leslie M. Golden. It's analogous to the
> increase in rotational speed that a twirling ice skater experiences when
> he or she draws in their arms. It is estimated that during the Sumatran
> quake, a block of material roughly 600 miles in length and 100 miles in
> width fell 30 feet closer to the Earth's axis of rotation. The planet
> has responded by rotating more rapidly, albeit ever so slightly, and our
> 24-hour days are now one ten-thousandth second shorter.
>
> Tom Skilling is chief meteorologist at WGN-TV. His forecasts can be seen
> Monday through Friday on WGN-TV News at noon and 9 p.m.
>
> * * * < end quote > * * *
>
> Michael D. Edmiston, Ph.D.
> Professor of Chemistry and Physics
> Bluffton University
> Bluffton, OH 45817
> (419)-358-3270
> edmiston@bluffton.edu


This is, no doubt, the stuff that sells papers. If you would like to draw your
own conclusions about exactly how incredible this tsunami event was, in
terms of day length, you might do worse than consult the public data
  provided by the International Earth Rotation Service at
  <http://www.iers.org/map/>

You could take a look at the figure 1 which shows variation in
day length 1993-1997 for example.     1 - 3 milliseconds per day is
  not out of the ordinary.

Under Products, you will find tabulations for Earth Orbit Parameters
maintained by the Navy:
<ftp://maia.usno.navy.mil/ser7/finals.daily>
and
<ftp://maia.usno.navy.mil/ser7/gpsrapid.daily>

There is a decode available there, but the first columns of the finals
are 4 12 26 for 2004 December 26, which is Modified Julian Date MJD  53365.0.
The gpsrapid table is marked out by MJD only.


Brian Whatcott    Altus OK    Eureka!