Lost Time

If your biological clock is off by a slight amount, you're not imagining things. The massive 8.8 magnitude earthquake in Chile did more than just kill people, damage property, and send killer waves into the ocean. It also knocked the earth off its access a bit and has shortened the length of the day. Now before anyone goes into a mass panic and runs for the hills because the end is near, it's not quite as dramatic as that. As it turns out, we've only lost 1.26 microseconds off of each day. That's one millionth of a second. Earth's axis was also tilted by about 3 inches. It's been described more or less as the same principle as a figure skater pulling their arms in and spinning faster.

It's not the first time this has happened either. Remember the 9.1 earthquake in Indonesia that spawned the tsunami that killed 250,000 people? That quake also shifted the Earth's axis and shortened our days by 6.8 microseconds. The awesome power of a single event like this is pretty staggering. That's a lot of rock that needs to get moved around for the rotational axis of the planet to shift.

Looking back through some of the bigger quakes on record, Chile suffered a 9.5 back in 1960. The maps indicate it was along the same fault line, but I can't find anything floating around out there to suggest whether it shifted the axis or shortened our days at all. Logically speaking it should have though.
.........................
"It is pointless to resist, my son." -- Darth Vader
"Resistance is futile." -- The Borg
"Mother's coming for me in the dragon ships. I don't like these itchy clothes, but I have to wear them or it frightens the fish." -- Thurindil

Well. I guess that's that then.

       
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Posted on Mar 7, 2010 3:25 am by Samson in: | 7 comment(s) [Closed]
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Interesting.
Did the Haiti quake do anything?

As an aside, has anyone else noticed the big cry for help for Haiti, and the virtually non-existent cry for help for Chile? Maybe it's just here in Canada but after Haiti all I saw on the news was other countries (well, including us) sending millions in relief help (of which they now probably have more money than their GNP ever was), yet no word on Chile save for a day of "oh, there was a quake in Chile".

       
Actually, the 9.5 quake in Chile back in 1960 was the highest magnitude earthquake on record, worldwide. At the time, they may not have had the means to accurately measure it's impact on the planet's axis though. For that matter, they may have just not thought to check either.

Hanaisse, I've seen news reports over AP since the Chile quake in which Chile did ask for aid, Obama sent Clinton there as our only aid that I know of so far (poor Chileans), but others in America have offered/pledged/sent aid.. Wiki's got a time line of the aid situation in Chile at [url]http://en.wikipedia.org/wiki/Timeline_of_relief_efforts_after_the_2010_Chile_earthquake[/url]. On the other hand, I would have to agree that it seemed like there was a significantly greater clamor over everyone needing to help out the poor Haitians (who so desperately needed help in quite a few ways before any disasters had even happened) than to help out our Chilean friends who really need some help for a change but had been quite able before the disaster. There's some interesting discussion about that very fact over at [url]http://www.city-data.com/forum/politics-other-controversies/910168-does-seem-like-theres-no-rush-2.html[/url].

As for what the Haiti quake did or didn't do to the earth's axis, I hadn't heard anything at all, but if the 8.8 quake in Chile only impacted the axis by 1.26 microseconds then the 7 quake in Haiti may well have had negligible effects. It may be that it takes an 8 on the richter scale to impact the axis of the Earth measurably. On the other hand, according to an article on this particular issue:
David Adam said:

Richard Gross, a geophysicist at Nasa's Jet Propulsion Laboratory in Pasadena, California, said the 8.8 magnitude quake could have moved the Earth's axis by 2.7 milliarcseconds (about 8cm) – enough to shorten a day by about 1.26 microseconds. [...] David Kerridge, a seismologist with the British Geological Survey, said the Chile and Sumatra earthquakes were based on subduction, in which one tectonic plate slides under another, redistributing the Earth's overall mass [...] Earthquakes caused by plates sliding past each other, such as the recent event in Haiti, do not have the same impact on the Earth's rotation.

Gross said the Chilean earthquake shifted the Earth's axis a greater distance than the larger Sumatran event because it was further from the equator. The fault that caused the Chilean quake also dips into the Earth at a steeper angle, which meant it moved more mass.

So, it would seem that, aside from the fact that the Haitian earthquake in question was 1.8 points lower on the richter scale (a difference in magnitude that's equivalent to roughly comparing an explosion produced by 32 billion tons of TNT to an explosion produced by 32 million tons of TNT, according to the nifty chart almost at the very bottom of the page at [url]http://www.seismo.unr.edu/ftp/pub/louie/class/100/magnitude.html[/url]), the earthquake in Haiti wasn't the right type of earthquake to impact the earth's axis that way either.

       
If it takes a quake the size of Chile to have an impact, I doubt we have the precision to measure what something as small as Haiti did. David Adam is probably right that it has a lot to do with the type of fault in question. Haiti being on a strike-slip fault while Chile's quakes happened on thrust faults. Unfortunately for us here in California, we have lots of both types of faults.

As far as the aid situation, given how poor Haiti's economy was before the quake and their lax earthquake codes, I'm perfectly willing to concede that they need more help despite Chile's quake being much larger and more devastating. I doubt you're going to see a death toll in Chile anywhere as close to what you saw in Haiti. Chile is not a backward mud hole. Many of the pictures I've seen just don't look anywhere near as bad.

       
I agree, either we don't have the precision or the impact is minor enough to not matter. On the other hand, there have only been a handful of quakes 8.0+ since people started recording/measuring how strong the quakes actually were and not that many more that were even 7.0+, but I would imagine, even before we started calculating how bad the quakes were, each one has had some little impact and cumulatively it's got to amount to something significant eventually. Much like the global warming matter though, I expect that it's really all a normal part of the planetary life cycle and not every earthquake that does have even a significant impact can all impact the axis the same way, perhaps they balance out in the long run with some shifting the axis a little left and some a little right sort of thing.

I think you're right that Haiti may very well have been more devastated by a lesser earthquake, but I expect that Chile had more to lose to begin with. You're probably also right that the death toll in Haiti will likely end up higher as well. But I think Chile is a better ally (potential ally?) than a small country that's actively fought us in the past on multiple occasions and which has very little comparatively to offer yet we're making much more fuss (publicly) about Haiti than Chile. I find that a bit disappointing. I could be much more understanding if we'd (globally speaking) determined there was less need in Chile but still at least made just as much media noise about it.

       
Cumulatively, yes, I'd expect that all of the 8.0+ sized quakes our planet has suffered before we took measurements, and perhaps even before we realized it wasn't the angry gods and such, have had a large enough impact on the length of the day to matter. Of course, there are other equally massive events that have happened on the planet, such as Krakatoa and Mt. St. Helens. Those too shifted mass but I would expect that to have the opposite result since they're flinging stuff out onto the surface. It probably all balanced out in the end, or for all we know is heavily in favor of lengthening the day which would account for global warming :)

It's the media. They praise our enemies and shun our allies. It surprises you at all that they're paying more attention to a hostile nation than to one that's our friend?

       
It's not the angry Gods!!?!?? :blink:

Thanks for the quote, Conner. The type of quake was probably something learned back in high school geography class but, yeah, that was a while ago. :lol:

All in all, very fascinating, and probably one of the "best learned facts" postings here.

       
Samson: Who knows, maybe reading/thinking something like that was what got Al Gore his Nobel in the first place. :lol:
In all seriousness, even knowing that it was a subduction quake, do we know if the result was that the land bowed inward or outward? Maybe it was still an addition to the surface area like one of the volcanos you mentioned by creating a new crest? Either way, I'd think there are bound to be a number of quakes, volcanos and other such major events that have impacted our axis in both directions by now.

I know, and it really shouldn't surprise me anymore, but it still does. Maybe surprise is the wrong word, perhaps it's just disappointment causing me to feel surprised that they haven't learned yet. :shrug:

Hanaisse: Well, you know.. there's nothing saying that it can't be that angry Gods are invoking the earthquakes even if we've figured out what they are. ;) :whistle:

You're very welcome. High school's been roughly just as far back for me too. But in this case, I don't recall seeing anything in the media about which type of quake either had been. Though when I first heard about the one in Chile I'd visited the U.S. Geological Survey Earthquake Hazards Program to get more info about it and they had mentioned that it was a subduction quake. (They have great info there about recent quakes worldwide, and very often recent means within minutes.) So, honestly it was probably a relearned fact for me as well, though I seem to vaguely recall learning something about it not in high school but back in roughly 5th grade (earth sciences), but then, that was even further back.. ;)

       
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