Chilean Earthquake Shortened Earth's Day

ailnlv writes "Days on Earth just got shorter. The recent earthquake in Chile shifted the planet's axis by about 8 cm and shortened days by 1.26 microseconds 'The changes can be modeled, though they're difficult to detect physically given their small size. ... Some changes may be more obvious, and islands may have shifted. ... Santa Maria Island off the coast near Concepcion, Chile’s second-largest city, may have been raised 2 meters (6 feet) as a result of the latest quake ...'"

Comments

GPS affected?

[johnny cashed]

Does this affect GPS for a short time? I understand that the USAF (or whoever runs it) will correct the system, but how quickly does this occur? Would it affect a JDAM bomb in flight, for example?

Re:GPS affected?

[Anonymous Coward]

It's not about the speed of the bomb. It's about the speed of the sattelites which orbit Earth and which the bomb uses to guide itself.

A sattelite travelling in Geostationary orbit clocks 3.8km/s. In 1.26 microseconds it would travel about 5mm. If it, say, takes a month until the government calculates and issues the correcting commands, the offset would accumulate to 15cm.

If a guided missile is launched to fly into a window of an enemy-occupied building, the offset can be enough to make a difference between hitting the window and hitting the wall.

Re:Did this affect climate

[c6gunner]

I actually liked the ACLU until I followed that link. Thanks a lot. Now I'm starting to wonder if they're any less crazy than the Ron Paul fanatics.

Re:Did this affect climate

[FooAtWFU]

You say this to make fun of the global warming debate, but theoretically it's not completely impossible that underground nuclear testing has something to do with the specifics of any earthquakes since the 1950s or so. Earthquakes are undoubtedly chaotic, and a series of megaton explosions underground might have shaken things a little and helped them get where they're going faster (temporarily).

Mind you, I'm not claiming that's necessarily the case either (or even probably the case). Just that, much like a decent conspiracy theory, it's not entirely nonsense or outside the realm of possibility. (I'd guess that overall seismicity remains the same overall but chaotic effects will change the locations of, say, half the aftershocks next century.)

USGS FAQ here.

Re:How often do such quakes occur?

[indi0144]

So what happens if instead of 100 8.3 eartquakes we have 10 @ 10.1?

From wikipedia:

>> Because of the logarithmic basis of the scale, each whole number increase in magnitude represents a tenfold increase in measured amplitude; in terms of energy, each whole number increase corresponds to an increase of about 31.6 times the amount of energy released.<<

This quake was 8.8 ram == 15.8 gigatons of TNT delivered
The one (the comet impact) that owned the dinosaurs was 13.0 ram or 100 teratons of TNT

And we really need one, very powerful in the right place at the right time to cause a polar swift. You know, after that you would start to see random Angels coming to Neo New York and Evas and stuff... no in all seriousness a polar swift will fuck us all big time.

http://en.wikipedia.org/wiki/Richter_magnitude_scale

Re:Not worth mentioning

[Animats]

The earth is naturally slowing down at a rate that makes this sort of thing hardly worth mentioning.

Actually, the slowdown is only about 2ms/century, or about 0.054 microseconds/day. So a 1-microsecond jump in a day should be noticeable. This information is tracked. Here's the raw data from the Earth Rotation Service.

With GPS systems working down to 15cm, changes like this get noticed.

Re:Great!

[tsm_sf]

The question to ask yourself is - stationary in relation to what?

Wasn't there a famous quote to the effect that you could say the earth was the center of the universe, but it just makes calculations needlessly difficult?

Re:Nit-Picking Science

[Khyber]

Okay, if this is the case, explain the sudden three inch drop in shadow (I use the shadow on a tarp to determine seasonal change) which usually indicates a full month of time passing, and this happening within two days of the earthquake.

I learned how to read time and the season by the shadows while in prison. Pretty neat when you learn how to do it, but this totally throws the estimation off.

Re:Did this affect climate

[Aceticon]

In Chaos Theory, a small change to the inputs can cause large changes to the results.

However the changes are just as likelly to go in one direction as they are to go in the opposite direction: the butterfly effect is just as likelly to result in a typhoon instead of clear weather as it is to result in clear weather instead of a typhoon.

Also, small changes to inputs can cause small changes to the outputs or even no changes at all (that's why it's called Chaos Theory) - plenty of butterflies flutter-about with out creating typhoons ;)

If indeed the system that underpins earthquakes is chaotic, underground nuclear tests are just as likelly to have brought forward quakes as they are to have delayed quakes as they are not not have had much effect at all - in fact, they're likelly to have done all of them.