Expert: Jayendra Upadhye - 1/20/2005

Question
Having read the science reports on the Earthquake in the indonesian region,I read that (Among other things)it Moved the noth pole an inch,Flattened out the bulge at the poles and sped up the rotation of the earth by a small fraction of a second.
my question(s)...
Does the rotation of the earth fluctuate?
Did it or will it slow back down?
How will (or could) this effect the planet long term?
Have humans ever recorded such an event??
Could this be the beginning of a major Climatic/geographic/orbital change over the next few hundred tousand years?


Answer
Hi Icon,
1 - Does the rotation of the earth fluctuate?
Actually it does, gradually!
The tidal action of the sun and moon combined, slows it down everyday by small fraction of a second.
That is why we have the leap second!
The american heritage dictionary defines it thus:-
A second of time, as measured by an atomic clock, added to or omitted from official timekeeping systems annually to compensate for changes in the rotation of the earth.
refer:- http://education.yahoo.com/reference/dictionary/entry?id=l0090250

Minor rate alterations such as the one you mention also happen from time to time.
The Cesium atomic clocks keeping national time, detect these errors and scientists add or subtract as required to get correct time again.

2 - Did it or will it slow back down?
As mentioned above, the slowing action is irrevocable and is tied to the action of the sun and the moon on the earth, dueto tidal coupling, whereby the earth's angular momentum is reduced and the moon speeded up. The moon as a consequence recedes from the earth at an annual recession rate of about 4 cm/year.

3 - How will (or could) this effect the planet long term?
Nothing!
In the beginning of 1883, was even worse, sending tsunamis that circled the earth, and was heard physically in australia! refer to the great tsunami page on THAT event at
http://www.drgeorgepc.com/Vocano1883Krakatoa.html
Events such as these though colossal to humans, are mere flutters for the earth! Its HUGE ANGULAR momentum is affected only in trace amounts, and it chugs along in its daily furrow unaffected.
It has done so for 4.5 billion years, survived the impact that created the moon, in it's early history (latest moon theory supports that), survived the massive meteorite hit in the gulf of mexico 65 million years ago, that killed of f the dinosaurs, and it will survive this one without even noticing it!

4 - Have humans ever recorded such an event?
As mentioned earlier, it already happened in 1883 in the sunda straits! where 1/3rd of the whole island blew up!
And dont forget the explosion of THERA! That completely wiped out a beautiful PRE-GREEK civilisation - The MINOAN - civilisation, on the island of CRETE.
[we owe the myth of the minotaur to that culture].

And ..who will forget POMPEII AND HERCULANEUM ..that fell prey to the pyroclaustic flows from Vesuvius?
ref:-http://volcano.und.nodak.edu/vwdocs/volc_images/img_vesuvius.html

5 - Well about climate I wouldnt know!
We all know weather and it's vagaries!
With all our super computers we have just about started to learn the abc of our climate, we are good at day to day predictions and maybe short-term perdictions, but we certainly are far from prediction long term changes!

Scientists routinely use upto 63 variables to predict the weather, who knows how many need to be added to answer your question?
So like asimov's galactic super computer answering on the reversal of entropy, i am forced to say.."insufficient data for a clear answer!"

so!
The earth has been around for 4.5 billion years not for nothing!
We CAN bank on it! :)
Jayen