[time-nuts] Result of Earth Quake speeds up earth?
jimlux at earthlink.net
Tue Mar 15 13:29:30 UTC 2011
On 3/15/11 6:20 AM, jimlux wrote:
> On 3/15/11 1:49 AM, Chris H wrote:
>> I hear in the Media that the earth quake sped the rotation of the earth
>> Can anyone confirm this?
> No.. the magnitude of the change is parts in 1E11 or thereabouts.
> Regular old tidal drag slowing is bigger, and that's what mostly
> contributes to leap seconds.
Another, potentially easier to detect, effect is that the axis of
rotation of the earth might have shifted.
An interesting question is whether earthquakes always lead to a speeding
up... Off hand, I would think that the general tendency is for the
gravitational forces to make the earth more smooth, which would probably
mean that the moment of inertia decreases (speeding up the rotation).
(that is, mountains fill ocean trenches in the long run).
On the other hand, rotational forces make the earth more oblate, which
increases the moment of inertia. I seem to recall that the inital
predictions of oblateness were made by assuming that there's an
equilibrium between gravitational forces pulling in and rotational
forces pulling out.
And this doesn't even get into the fact that the earth is somewhat pear
shaped: wider south of the equator than north. ( most certainly not a
banana shape as reported by Sir Bedivere, but what would a medieval
experimenter with swallows know anyway)
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