earthquakes

[Bodhi Dharma Zen]

My first guess is that they would be completely unpredictable, but I might be wrong. My (uneducated) common sense says that after a "big one" (grossly defined at about 7 on the Richter) the rest are replicas, but, it could be otherwise, or they might not be related at all. Where can I find more about this? I have looked here and there but can find no straight answers.

I'm currently living in Mexico City, and, apparently, they have been a lot more this year than previous years. I have no idea.

[MG1962]

This will get you started

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

[Bodhi Dharma Zen]

thanks, in the references I found this:

http://128.197.153.21/rea/web_online...lzer_feb04.PDF

interesting, but not conclusive... I would like to talk to an expert in the field, there most be at least one at the JREF

[MG1962]

Originally Posted by Bodhi Dharma Zen

thanks, in the references I found this:

http://128.197.153.21/rea/web_online...lzer_feb04.PDF

interesting, but not conclusive... I would like to talk to an expert in the field, there most be at least one at the JREF

Send a private message to Dinwar, he is our resident geologist

[Bodhi Dharma Zen]

thanks mg1962, I will

[IndridCold]

Anyone know anything about HAARP?

A friend told me America is attacking people with Tesla's death ray.

[shadron]

Yes, there are a number of engineers and scientists here who understand HAARP and Nicola Tesla's inventions. The combination of the two in a sentence, particularly when suggested by a friend, is generally considered to constitute a Conspiracy Theory, and is pursued in the CT section of this forum. Adding the word "attack" is most definitely a conspiracy theory.

[IndridCold]

Thanks so helpful and not just being Richard.

[shadron]

All that can be said with evidence about HAARP and Tesla is that the gov may have looked over Tesla's papers before forwarding them to his family in Croatia after he died. He was not the only failed genius scientist of the times; look up Barnsworth and Armstrong, for others. There may have been something revolutionary in the papers, though that's becoming more and more weak over time; the man wasn't an omniscient being. There is a real HAARP project in Alaska, run by the university there, which is a rather small antenna field; as it is a DARPA-funded project, it's results are classified. That's it. The rest is speculation.

[MG1962]

Originally Posted by shadron

All that can be said with evidence about HAARP and Tesla is that the gov may have looked over Tesla's papers before forwarding them to his family in Croatia after he died. He was not the only failed genius scientist of the times; look up Barnsworth and Armstrong, for others. There may have been something revolutionary in the papers, though that's becoming more and more weak over time; the man wasn't an omniscient being. There is a real HAARP project in Alaska, run by the university there, which is a rather small antenna field; as it is a DARPA-funded project, it's results are classified. That's it. The rest is speculation.

Which has open days once a month - so much for high security super secret installation

[CORed]

Originally Posted by shadron

All that can be said with evidence about HAARP and Tesla is that the gov may have looked over Tesla's papers before forwarding them to his family in Croatia after he died. He was not the only failed genius scientist of the times; look up Barnsworth and Armstrong, for others. There may have been something revolutionary in the papers, though that's becoming more and more weak over time; the man wasn't an omniscient being. There is a real HAARP project in Alaska, run by the university there, which is a rather small antenna field; as it is a DARPA-funded project, it's results are classified. That's it. The rest is speculation.

The truth is that while he was a brilliant inventor and engineer in the early part of his life, Tesla became quite a crackpot in his later years. He made a lot of claims about amazing inventions in his later years, but most of those "inventions" existed only on paper or in his head, the "death ray" among them.

[Dinwar]

I got the PM, and have been thinking about this. There are two parts to this question: First, can we predict WHERE? and secon, can we predict WHEN?

Where is easier: quakes tend to focus on tectonic boundaries. However, there are nuances. Tectonic boundaries are enormously complex, and that complexity means that they're usually fuzzy--it's incredibly difficult to identify where the boundary starts and stops. It's not like you see in the movies, where there's a crack in the ground and that's the fault. That said, there are some generalizations that can be made. For example, deep quakes (like the 9.0 that rocked Asia a few years back) tend to occur in the deep slabs of subducted oceanic crust under convergent boundaries. They tend to be a good distance from the surface of the boundary, but they're still part of it. Shallow quakes tend to cluster around the surface expression of the fault, as they're caused by the deformation of the surface rock by the fault. They tend to be more minor (though they can still be pretty powerful), since they don't involve slabs of rock that weigh as much as Japan (or more!).

You can also get earthquakes in ancient faults, which is what happens along the USA's east coast. Some of the faults were due to the formation of Pangea, and then the later rifting that formed the Atlantic; some are, as I understand it, much older. Those areas can be re-activated by various processes, and are difficult to understand because they're between the deep epicenters and the shallow ones, and far from any current tectonic boundaries.

Pull-apart basins such as the Basin and Range can generate earthquakes because, well, it's the start of a tectonic boundary. As the continents pull apart, normal faults occur as huge blocks of rock move downward relative to everything else.

Hot-spot volcanism can generate seismic activity as well, for exactly the opposite reason as the pull-apart basins: huge blocks fo rock are moving UP relative to everything else, sometimes quite explosively (Yellowstone, for example).

When is much, much trickier. I suppose in theory we could calculate it if we knew all the factors--Poison's Ratio of the rocks involved, strain rate, pore fluid pressure, Sigma 1, 2, and 3, all that fun stuff. Unfortunately, the only way to learn all of that is to excavate the feature, which destroys the system (or at least substantially alters it). And if the stresses are great enough less-intrusive methods like drilling won't work, because the pressure of the rock will deform the drill bits. The hole in Russia being drilled to the MoHo Discontinuity ran into that problem--couldn't keep the bits the right shape. And those are expensive buggers, too.

There are ways to predict quakes. For example, a large quake will almost always trigger smaller aftershocks and even large-scale quakes. That said, these can happen weeks or even months after the main quake. Earthquakes shift the system, releasing some stresses and generating others, and it takes a long time for the system to re-equilibrate sometimes. And if you've got numerous small quakes happening that may be a predictor for a larger quake--though this is by no means certain.

The tl;dr version is that right now, at the level of technology we have, it's simply not possible to predict earthquakes with anything resembling accuracy. We've got a good sense of the where (except when things hit us out of the blue), but as far as when goes it may as well be entirely random as far as prediction is concerned.

There's another geologist on this site you may also want to talk to: Correa Neto. He's better versed in hard-rock geology than I am, and may be able to provide more specific data.

[Bodhi Dharma Zen]

Originally Posted by Dinwar

There are ways to predict quakes. For example, a large quake will almost always trigger smaller aftershocks and even large-scale quakes. That said, these can happen weeks or even months after the main quake. Earthquakes shift the system, releasing some stresses and generating others, and it takes a long time for the system to re-equilibrate sometimes. And if you've got numerous small quakes happening that may be a predictor for a larger quake--though this is by no means certain.

Thanks Dinwar... well, what makes me think is that the evidence for determine if something is an aftershock or a pre-shock is always ad-hoc and it comes after the facts, so, I believe (I could be wrong) that the scale is arbitrary and so it is useless. I believe they quantify earthquakes about certain level (somewhere around 6) to be the main events and everything below to be pre and post... but... what if you have say, 40 of around 5 grades, and then one of about 6.5... how can you know that even that 6.5 is just a pre for a bigger (say 8)?

I also found this article:

http://www.usgs.gov/blogs/features/u...de/?from=title

And it doesn't look nice... apparently, there has been an increment which is still unexplained... that triggers another alarm in my head, as in Mexico there has been, (so far this year) a hell lot more earthquakes than in previous years... of course, I rely in people's experiences and so I'm not talking about objective facts, but about subjective facts...

[jj]

Originally Posted by CORed

The truth is that while he was a brilliant inventor and engineer in the early part of his life, Tesla became quite a crackpot in his later years. He made a lot of claims about amazing inventions in his later years, but most of those "inventions" existed only on paper or in his head, the "death ray" among them.

It appears in fact that he may have been poisoned by some of his chemical experiments.

[Dinwar]

Originally Posted by Bodhi Dharma Zen

well, what makes me think is that the evidence for determine if something is an aftershock or a pre-shock is always ad-hoc and it comes after the facts, so, I believe (I could be wrong) that the scale is arbitrary and so it is useless.

Somewhat true. If you start seeing clusters of earthquakes you can sort of guess that there's going to be a bigger one coming, sometimes. And the aftershocks are pretty well known. The thing is, what this nomenclature amounts to is drawing a line at the biggest quake and defining everything before it as "foreshocks" and everything after as "aftershocks". Some interesting data can be gathered from these for geophysical examinations (the structure of the Earth's layers, for example), but for the sake of earthquake prediction, you are correct.

Quote:

I believe they quantify earthquakes about certain level (somewhere around 6) to be the main events and everything below to be pre and post... but... what if you have say, 40 of around 5 grades, and then one of about 6.5... how can you know that even that 6.5 is just a pre for a bigger (say 8)?

Well, that's just it--you can't. Not without spending a huge amount of time, money, and resources on a project that likely won't work anyway. Sometimes a string of minor quakes is what's actually happening. A quake is all about releasing stress. Sometimes this is accomplished via a string of small quakes, and others it's accomplished by one big one.

And 6 isn't necessarily the cut-off. It's more temporal. You can have foreshocks for a 4.0 quake.

The increase is...odd. However, you have to remember that the central/western part of the USA is a rift zone. It's not clear if it's active or not. Los Vegas is a center for such research, but right now the consensus is "I dunno". I know of a few areas where massive amounts of lava flowed about 5 million years ago, and that's not an unreasonable amount of downtime for a rift zone.

[Bodhi Dharma Zen]

Thanks Dinwar.

[Westwall]

Originally Posted by CORed

The truth is that while he was a brilliant inventor and engineer in the early part of his life, Tesla became quite a crackpot in his later years. He made a lot of claims about amazing inventions in his later years, but most of those "inventions" existed only on paper or in his head, the "death ray" among them.

This is unfortunately a common problem with genius's. Capybara, the great chess master was famous for not being able to sleep unless he had a pawn on each bed post.

[Westwall]

Originally Posted by Dinwar

I got the PM, and have been thinking about this. There are two parts to this question: First, can we predict WHERE? and secon, can we predict WHEN?

Where is easier: quakes tend to focus on tectonic boundaries. However, there are nuances. Tectonic boundaries are enormously complex, and that complexity means that they're usually fuzzy--it's incredibly difficult to identify where the boundary starts and stops. It's not like you see in the movies, where there's a crack in the ground and that's the fault. That said, there are some generalizations that can be made. For example, deep quakes (like the 9.0 that rocked Asia a few years back) tend to occur in the deep slabs of subducted oceanic crust under convergent boundaries. They tend to be a good distance from the surface of the boundary, but they're still part of it. Shallow quakes tend to cluster around the surface expression of the fault, as they're caused by the deformation of the surface rock by the fault. They tend to be more minor (though they can still be pretty powerful), since they don't involve slabs of rock that weigh as much as Japan (or more!).

You can also get earthquakes in ancient faults, which is what happens along the USA's east coast. Some of the faults were due to the formation of Pangea, and then the later rifting that formed the Atlantic; some are, as I understand it, much older. Those areas can be re-activated by various processes, and are difficult to understand because they're between the deep epicenters and the shallow ones, and far from any current tectonic boundaries.

Pull-apart basins such as the Basin and Range can generate earthquakes because, well, it's the start of a tectonic boundary. As the continents pull apart, normal faults occur as huge blocks of rock move downward relative to everything else.

Hot-spot volcanism can generate seismic activity as well, for exactly the opposite reason as the pull-apart basins: huge blocks fo rock are moving UP relative to everything else, sometimes quite explosively (Yellowstone, for example).

When is much, much trickier. I suppose in theory we could calculate it if we knew all the factors--Poison's Ratio of the rocks involved, strain rate, pore fluid pressure, Sigma 1, 2, and 3, all that fun stuff. Unfortunately, the only way to learn all of that is to excavate the feature, which destroys the system (or at least substantially alters it). And if the stresses are great enough less-intrusive methods like drilling won't work, because the pressure of the rock will deform the drill bits. The hole in Russia being drilled to the MoHo Discontinuity ran into that problem--couldn't keep the bits the right shape. And those are expensive buggers, too.

There are ways to predict quakes. For example, a large quake will almost always trigger smaller aftershocks and even large-scale quakes. That said, these can happen weeks or even months after the main quake. Earthquakes shift the system, releasing some stresses and generating others, and it takes a long time for the system to re-equilibrate sometimes. And if you've got numerous small quakes happening that may be a predictor for a larger quake--though this is by no means certain.

The tl;dr version is that right now, at the level of technology we have, it's simply not possible to predict earthquakes with anything resembling accuracy. We've got a good sense of the where (except when things hit us out of the blue), but as far as when goes it may as well be entirely random as far as prediction is concerned.

There's another geologist on this site you may also want to talk to: Correa Neto. He's better versed in hard-rock geology than I am, and may be able to provide more specific data.

A good synopsis. There is also a theory put forth by the Japanese seismologist Dr. Kiyoo Mogi in 1969, I think is when i first heard of it, where a series of small earthquakes in a ring shape presage a major break within the area of the "donut". Hence the name Mogi Donut.

[MattTheTubaGuy]

certain earthquakes are somewhat predictable.
major earthquakes occur on the plate boundaries at semi regular intervals, so if you know when the last few quakes occured, it would be possible to estimate when it would be most likely to go off next. for example, the Alpine Fault in New Zealand has ruptured 4 times (I think) in the last 1000 years, the last time was around 300 years ago, so it is expected it will go sometime soon, I will probably experience it in my lifetime.

Aftershock sequences are reasonably predictable.
I know from personal experience that large earthquakes have lots of aftershocks immediately after the quake, and the frequency decreases with time.
The individual aftershocks are also unpredictable. sometimes there will be quite a few in one day, other times, I feel none for several days, and occasionally, there is a big one that even has its own aftershock sequence!
I have made a few graphs in Excel and I have found that the frequency approximately follows an exponential curve, and the magnitude distribution follows very closely to an exponential curve down to a certain magnitude where the detectors can't detect them all, but the complete part of the curve can be extrapolated. I think I found that for each magnitude decrease, there was an increase of quakes of about 8 times, so for each 5, there were 8 4's, 64 3's, 512 2's (approximately). I have heard that typically it is a factor of 10, but i guess it would vary depending on the local geological conditions.

I'm not a geologist, I have just had to put up with a few thousand quakes over the last couple of years here in Christchurch, New Zealand!