[time-nuts] Result of Earth Quake speeds up earth?

jimlux 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
>> up..
>> 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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