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Author Topic:   Heat release from tectonic friction
mindspawn
Member (Idle past 2679 days)
Posts: 1015
Joined: 10-22-2012


Message 92 of 102 (687668)
01-15-2013 9:21 AM
Reply to: Message 88 by TrueCreation
12-21-2012 5:00 PM


Re: Back of envelope calculation
TrueCreation, I don't know the science behind it, but am not fully convinced about the whole heat creation argument. It all depends on HOW two plates collide. If the one simply sinks below the other, the heat creation is a lot less than if one collides into another as in mountain building processes. I am not mathematical, I could never work out the amount of heat generated for the formation of the main mountain ranges, but surely the heat generated would be limited to the formation of existing mountain ranges? ie what effect would the heat generated in the creation of the Himalayas over say 800 years have on the earth?
Two plates sliding over one another as per the Japanese quake, 50 m of ocean floor lost in one day, had no significant heat effects.
Same as the splitting of the Afar rift in 2005, in some areas it split by 30M wide, with no descernible heat effects. So the observed reality as opposed to the theory, is that its possible to have continuous continental drift of many meters in one day, without any significant effects, both in subduction and spreading zones.
Edited by mindspawn, : No reason given.
Edited by mindspawn, : No reason given.

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 Message 88 by TrueCreation, posted 12-21-2012 5:00 PM TrueCreation has not replied

Replies to this message:
 Message 93 by Larni, posted 01-16-2013 3:42 AM mindspawn has replied
 Message 100 by herebedragons, posted 01-18-2013 6:28 PM mindspawn has not replied

  
mindspawn
Member (Idle past 2679 days)
Posts: 1015
Joined: 10-22-2012


Message 94 of 102 (687737)
01-16-2013 9:06 AM
Reply to: Message 93 by Larni
01-16-2013 3:42 AM


Re: Back of envelope calculation
It seems there have not been much studies on the actual temperatures at subduction zones, so all the maths is just speculation. Just through deductive reasoning its pretty clear that if you move two plates past each other there is less friction than if you collide or grind them roughly into each other. So speculate all you want on the maths, if two plates slide smoothly over one another, this has less effect than if two plates collide, and the effect is as yet unquantified. Guesswork.
Moore Foundation grant funds study of Tohoku earthquake fault
Brodsky, a professor of Earth and planetary sciences, helped organize the Japan Trench Fast Drilling Project (JFAST), which successfully drilled across the Tohoku earthquake fault earlier this year and installed a temperature observatory on the fault. The observatory allows scientists for the first time to measure the frictional heat produced by the fault slip of a great subduction-zone earthquake.
Earthquakes occur as giant plates in the Earth's crust grind past each other. Tectonic forces push the plates forward, while friction on the faults between plates holds them back. According to Brodsky, the lack of measurements of the frictional force during the sliding motion of an earthquake is one of the major impediments to progress in earthquake science.
"Observing and analyzing the temperature on the fault following the recent magnitude 9 Tohoku earthquake provides a unique and probably never-again achievable window into this critical value," Brodsky said. "What we learn will inform and prepare us for the next earthquakes, including the one predicted for the Cascadian subduction zone that lies along the coast of Oregon and Washington."

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 Message 96 by NoNukes, posted 01-16-2013 4:56 PM mindspawn has replied

  
mindspawn
Member (Idle past 2679 days)
Posts: 1015
Joined: 10-22-2012


Message 97 of 102 (687804)
01-16-2013 5:07 PM
Reply to: Message 96 by NoNukes
01-16-2013 4:56 PM


Re: Back of envelope calculation
You aren't describing the problem set up here. At least not as I understand it.
Basically, the issue here is that if the world is only 6000 years old, then the plates must originally have been moving really fast to get into their current position. Currently the plates are observed to be moving far more slowly. That loss of kinetic energy is from friction. We can say something about the magnitude of the energy involved and about the time involved. We don't have to speculate about what happens when the plates slide smoothly over each other because that would not produce slowing.
Thanks for explaining that. I believe the slowdown is more related to less mantle instability than kinetic forces (and friction) in the crust itself. But whether the heat under discussion relates to the original kinetic forces and friction, or the friction related to the slowdown of the tectonic activity, the same logic applies, they are still trying to measure tectonic related temperature changes.
Edited by mindspawn, : No reason given.

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 Message 96 by NoNukes, posted 01-16-2013 4:56 PM NoNukes has replied

Replies to this message:
 Message 98 by NoNukes, posted 01-17-2013 12:13 PM mindspawn has replied

  
mindspawn
Member (Idle past 2679 days)
Posts: 1015
Joined: 10-22-2012


Message 99 of 102 (687884)
01-17-2013 12:56 PM
Reply to: Message 98 by NoNukes
01-17-2013 12:13 PM


Re: Back of envelope calculation
Makes sense, I have to admit there would be significant friction for the slowdown. Let's see what the Japan studies reveal.

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 Message 98 by NoNukes, posted 01-17-2013 12:13 PM NoNukes has seen this message but not replied

  
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