Magnetic reversals and other badass geology

That was an interesting article, but one part towards the end is bullshit. The history channel scenario about the poles shifting is bullshit as well, but this part where they refute it:

"Scientists say that, at best, the poles might change location by one degree over a million years, with no sign that it would start in 2012."

is a load of crap. The magnetic poles have shifted by more than 1 degree in the past 100 years, even 50 years, much less 1 million. If they are talking about the geographic poles I don't know what the fuck they are talking about - unless the history channel thinks the earth is going to turn upside down - so I assume they mean the magnetic poles.

I was going to point that out, but I wasn't too sure about one thing: even if the poles flipped, it wouldn't cause any problems for anything but like... compasses, right? I remember learning in some science class that it has happened before, but the teacher made it seem like it wasn't too big of a deal. There was no mention of "The entire mantle of the earth would shift in a matter of days, perhaps hours, changing the position of the north and south poles, causing worldwide disaster". Maybe the teacher just didn't want to scare us.

Enlighten me! Would it, or would it not, cause mass destruction? Cause I can totally picture every scrap of iron in the world trying to realign itself to the south pole all at once...

A lot think it would be catastrophic. I guess nobody truly knows until it happens....if it happens.

I think if any major disaster happens to earth to the point of bringing Humans on the brink of extinction, like the Dinos, it would be something to do with the Sun.

I don't think iron would have to "realign" itself to a pole, I mean, that would make cars undriveable because they would always be trying to point themselves north... right? Just using pharren's logic...

I was being facetious. Like I said, I was always under the impression that the only thing that would change is compasses would now point south instead of north. Vulash is a geologist, that's why I'm asking him what would (theoretically) happen, if anything. I can't come up with any reason why it would create a disaster.

I figured you were, I just suppose I was echoing your thought that it doesn't make sense that bad earth-exploding things would happen.

The simple answer is we don't know - both in terms of time, and effects.

There are a lot of theories (based on things, not just hogwash) - but the worst one is simply that our magnetic field shields us from radiation from the sun - during a reversal there is most likely a time when the field is down as it changes. So some thing exposure could be a serious issue - even on the scale of wiping us out. The counter to this is that it has happened in the past (not in human times) and organisms survived - there isn't any data that these reversals have occurred at the same time as any of the mass extinctions in the fossil record.

The less scary stuff is things like it would screw up our radio waves big time - so cell communication, radios, etc would all go haywire which would cause some problems obviously.

But the fact is we don't know - its a pretty interesting field, and I'm not an expert. The other thing is this could happen over the period of thousands of years, or happen very rapidly. Also the events appear to happen at random - so there is no way the Mayan's could have predicted it.

I will say that Earth's magnetic field is in decline right now - it has decreased by very measurable margins over the last century.

Oh and iron wouldn't need to realign I don't think. One of the cool things we do with paleomagnetism is: well to start when lava cools the magnetic minerals align themselves with the current magnetic north - so if you find a rock like a basalt in situ then you can measure in a sense where magnetic north was when it cooled. Obviously its a lot more complicated than that, but that is the short description. So any new forming rocks would be affected, but I don't think any current ones would.

It's after midnight and I typed this all from memory - so if you want more details, or I skipped over a small detail forgive me and just let me know.

http://www.geomag.bgs.ac.uk/reversals.html

Looks as though they disagree slightly with what I've learned, but that is normal. Apparently humans have been around for millions of years? I guess that is why I study the earth and not people :)

I would say this information is more up to date as far as the effects of shielding than what I've read in textbooks or from professors who aren't experts in that field.

It's a pretty fascinating field of study. So much going on all the time with the earth, Vulash, what's your take on the Indonesian earthquakes? I was just reading that some groups are suggesting they are linked.

Do you mean the one that just happened and the one that caused the massive Tsunami? I was actually walking by the seismograph when the one a couple of weeks ago hit - that was pretty wild. They're both right in the same subduction zone - so in that sense they are linked. I don't know what the group is saying, and I probably wouldn't have the knowledge to give a valid comment anyway. Are they saying the slip in the first one caused the second one to go off sooner?

I know there are some EQs in Turkey they've studied where the EQs move more or less east to west (I think) because one triggers, and the motion of the movement increases the stress in that direction - so typically the next time one goes off its just to the west of the previous one, and so one. They're still going off several decades apart. So I would say they're definitely linked in the sense of overall motion of the plate boundary, but it sounds like you're saying they're doing a study and showing an even closer link than that - and in that case i have no idea :P There is so much going on, and there are so many fields in geology that its just not possible to keep up with it all. Keep in mind also that I graduate this May so I'm far from an expert in any field.

This is what I was reading on the quakes.. http://www.abc.net.au/news/stories/2009/10/12/2711930.htm

When you graduate, where do you hope to work? I remember really enjoying geology, even when other kids were rolling their eyes and saying rocks are boring :) I think it is pretty damn cool that you can tell so much about the earth from the ground.

Boy, talk about a derail /giggle

Maybe we should just start a geology thread :P I love talking about this stuff, but I don't want to derail too badly. I think the movie will be fun to watch - especially as someone interested in this stuff because its fun to make fun of it, and I'm fully capable of putting that aside to enjoy the movie - then make fun of it :) We actually have a "bad geology movie night" quite often here in my department. There are some good ones out there.

As far as the EQ linkage - I read the article and I just have to say that is out of my league. I'm not quite as interested in seismology, and those are top scientists in that field - the article doesn't sound complicated, but the physics behind the wave calculations and fault stress that they do is unbelievable. All I really know is that there are waves that travel around the entire earth and then rebound and amplify each other after major earthquakes - so it almost sounds like they're saying that the force behind those is enough to weaken other areas? I'm just not sure that is how it works, but I can't argue with them obviously.

Back to paleomagnetism and Pharren's question. I actually talked to a professor today because I was interested, and I mainly learned about it from an intro class 3 years ago (with a little here and there since). They've done a lot with modeling and advancing in this field in the past 3 years so he updated me a little.

First he said it sounded like the journalist either read a very old article or simply didn't understand what he was being told - the statement in question is just flat out wrong. He said that current modeling seems to be pretty indicative of what we see in the record, and they estimate now that the shift would be on the order of 3000 years to complete. Also he confirmed that there is simply no evidence of any of the mass extinctions matching up with any of the known reversals, and obviously life survived through those reversals without any known hiccups in the record.

One other issue he did tell me though that I was unaware of was one we see today at the poles. The Auroras we get at the poles are a result of solar winds coming in and at the poles the magnetic field behaves quite differently so we get the auroras. As the field weakens these can come all the way to the ground and super charge the ground, and cause power grids to fail. This actually happens now. During a reversal it would be possible for this to happen on a larger scale, and our power grids would have to do something different to compensate. If it happens on the time scale that we anticipate though it would be a slow process to humans and we'd have time to do that.

There is more but I have carpal tunnel and my wrist is seizing up so I'll finish when I get home.

Roz can you move our derail here? That way we can keep it going without continuing to go further off topic :D Thanks!

What derail? I've been gone the past couple of days so I have no idea what you mean. =x

Nevermind, I found the derail. =) Enjoy.

Thanks Roz!

The other thing I was going to add is that the modeling they've done also shows that during the reversal the magnetic field gets very chaotic. They've found rock from volcanic eruptions that happened during these reversals, and in those the paleomagnetism has also been chaotic. In one example they showed magnetic north changing by up to 60 degrees over 3 feet of volcanic rock - which would be the equivalent of about a day. So you could actually sit and watch the needle on a compass move during something like that.