From: Gary Horne (garyhorne@mac.com)
Date: Fri Dec 31 2004 - 19:51:50 PST
Message-Id: <77A2F3EF-5BA8-11D9-9919-0030654C6092@mac.com> From: Gary Horne <garyhorne@mac.com> Subject: Re: pinhole earth rotation Date: Fri, 31 Dec 2004 19:51:50 -0800
But Paul, what do you say of my Kinetic Energy calculation? Is that
invalid? Isn't that an easy way to show that the effects of the
earthquake, however real, are going to be awfully small compared to the
normal rotation (and variance in rotation) of Earth?
Gary
On Dec 29, 2004, at 9:53 AM, Paul Doherty wrote:
> Here is what a theoretician calculates,
> I await the experimental measurements.
>
> I believe the effects will be accurately measurable.
>
> "The deadly Asian earthquake may have permanently accelerated the
> Earth's
> rotation--shortening days by a fraction of a
> second--and caused the planet to wobble on its axis, U.S. scientists
> said
> Tuesday.
>
> Richard Gross, a geophysicist with NASA's Jet Propulsion Laboratory in
> California, theorized that a shift of mass toward the Earth's center
> during
> the
> quake on Sunday caused the planet to spin 3 microseconds, or 3
> millionths
> of a second, faster and to tilt about an inch on its axis.
>
> When one huge tectonic plate beneath the Indian Ocean was forced below
> the
> edge of another "it had the effect of making the Earth more compact and
> spinning faster," Gross said.
>
> Gross said changes predicted by his model probably are too minuscule
> to be
> detected by a global positioning satellite network that routinely
> measures
> changes in Earth's spin, but said the data may reveal a slight wobble.
>
> The Earth's poles travel a circular path that normally varies by about
> 33
> feet, so an added wobble of an inch is unlikely to cause long-term
> effects,
> he said.
>
> "That continual motion is just used to changing," Gross said. "The
> rotation
> is not actually that precise. The Earth does slow down and change its
> rate
> of
> rotation."
>
> When those tiny variations accumulate, planetary scientists must add a
> "leap second" to the end of a year, something that has not been done
> in many
> years, Gross said.
>
> Scientists have long theorized that changes on the Earth's surface
> such as
> tide and groundwater shifts and weather could affect its spin but they
> have
> not
> had precise measurements to prove it, Caltech seismologist Hiroo
> Kanamori
> said.
>
> "Even for a very large event, the effect is very small," Kanamori said.
> "It's very difficult to change the rotation rate substantially."
>
>
>
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