[LEAPSECS] What happened in the late 1990s to slow the rate of leap seconds?

[Poul-Henning Kamp]

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>> We don't know, but the period had other pecularities, for instance
>>almost statistically significant level of vulcanism.

>“Almost statistically significant” is like “a little bit not pregnant” ;-)

Indeed.

That's why I stressed the uncertainty.

The original paper is here:

	http://www.nature.com/ngeo/journal/v7/n3/full/ngeo2098.html

Their angle is climatic, but I couldn't help notice that the period
they study remarkably coincident with the leap-second "hiatus".

I havn't seen anything even remotely close to a geophysical hypothesis
about the leap-second "hiatus", and this one isn't much of one either.

The major earth-quakes you cite mainly affect LOD via angular
momentum.

If volcanism can affect the "lubrication" between core and
mantle, that in turn can give rise to much larger LOD effects.

That is not physically impossible inside our current (lack of)
knowledge - and that is about all we can say.

So it's not a particular strong hypothesis, most likely just a
coincidence, but if we keep an eye on it in the future, we
may be able to either rule it out or refine it.

The interesting footnote is that *if* the core/mantle interface is
that sensitive, melting most of the ice on Greenland is likely
to impact on both earthquake patterns and LOD significantly.

But the important part in my original answer is what comes
before the comma: "We don't know."

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