Slashdot Mirror
Killer Qualities of Japanese Fault Revealed
Lasrick sends this report from Nature News:
"The devastating 2011 earthquake and tsunami in Japan shocked researchers who did not expect that the seismic fault involved could release so much energy. Now the world's deepest-drilling oceanographic ship has been able to pin down the odd geology that made this disaster so horrific. The fault turns out to be unusually thin and weak, the researchers report in Science this week1–3. The results will help to pin down whether other offshore faults around the world are capable of triggering the same scale of disaster. ... The coring revealed a very thin clay layer, about 5 meters thick, separating the two sliding tectonic plates (abstract). 'That’s just weird,' says Emily Brodsky of the University of California, Santa Cruz (UCSC), who is an author on all three Science papers this week. 'Usually it’s tens of meters or more.' Lab tests confirmed that this wet clay layer is extremely slippery, and gets even more so under stress (abstract). As sliding creates friction and heat, water in the clay gets pressurized and pushes up against the impermeable rock around it. That 'jacks open the fault” says Brodsky, allowing it to slip even more. The temperature sensors found that more than a year after the quake, the fault was still up to 0.31 C warmer than its surroundings (abstract). From this they could extrapolate how much heat was generated from friction during the sliding event. Their calculations confirmed the very low friction of the 5-meter-thick clay layer."
How in the fuck can it be claimed that it's "just weird"? That's bullshit. This isn't "weird".
Statistically, five meters really isn't much different from ten meters, or twenty meters, or even thirty meters. It's only when you get to about 80 meters or so that we see a statistically-significant deviation from the standard probability distributions.
If anything in this situation is "just weird", I'd have to say that it's the Japanese style of animation, and its content. Low-quality animation depicting tentacle molestation is truly "just weird" and it is also severely abnormal, from a statistical perspective.
The first couple times I saw the title I thought it said "Killer Qualities of Japanese Fruit Revealed". Granted, that also could have been really interesting.
Damn_registrars has no butt-hole. Damn_registrars has no use for a butt-hole.
Perhaps by drilling millions of holes; and driving millions of rods of steel rebar into the clay, to reinforce the fault line.
Yeah, that'll totally prevent any further earthquakes, for sure. After all, it's a fault line that's only 1250 km long. It's merely 230 billion tonnes of rock in one of the smallest Pacific plates pushing against the Siberio-Eurasian plate that's estimated to weigh upward of 7.4 trillion tonnes. We're only talking about roughly 25 billion Joules of energy involved during minor seismic events, and upwards of 150 billion Joules during more severe quakes. And the fault line is only under 14 km of water, where even sending down the most basic of probes and drilling apparatus is extremely difficult and costly (like the article makes blatantly obvious, had you bothered to read it).
What you say is totally plausible and economically feasible. I would be very surprised if they don't do exactly what you propose, and have it fixed up within maybe 6 to 8 months. Some rebar and concrete is clearly the solution. Clearly.
What is the thermal time constant of a tectonic plate? Surely someone of your renown in geologic circles must have that basic information on hand?
Coastal communities did not have an adequate evac or preparation or post disaster plan. All they had were political cosmetics.
Nuclear facilities did not have an adequate evac or preparation or post disaster plan. All they had were political cosmetics.
A delta in T of 0.31 C has no practical value even if the P-value is 0.01 (it is significantly meaningless); just another political cosmetic.
Japanese women call men like the above, "Herbivores."
Extremely low radio frequencies pulsed from a dipole array of antennae and bounced off the ionosphere from GOD knows where hit that country and mark my words, someone will pay big time.
That would never work.
But placing explosives or some sort of nuclear devices in at regular intervals to release stress might work.
There is no fixed answer to that. The density isn't uniform, the thickness isn't uniform, the thermal conductivity isn't uniform, the surface roughness and flow rates of currents past the surface aren't uniform.
It's nice to come up with models, but one has to be cautious of the output when it involves making many assumptions.
Some fluctuations in volcanic activity can be expected from variations in geomagnetic activity.
The effects of some variations propagate more quickly than previously believed.
http://www.latimes.com/news/science/sciencenow/la-sci-sn-volcano-mantle-magma-highway-to-hell-20130801,0,1351433.story
Just get some Utah Boy Scout leaders to give that fault a nice shove. It's all about saving lives!
...water in the clay gets pressurized and pushes up against the impermeable rock around it. That 'jacks open the fault” says Brodsky, allowing it to slip even more....
That spells fracking in my book. And we already know that fracking causes earthquakes and pollutes drinking water. Now we know that it pollutes sea water as well, and causes nuclear reactors to explode. Wind Turbines would never do this...
So the clay is 0.31 C hotter than the surroundings. They state that this is due to friction during the earthquake a year before it was measured. How do we know that the clay wasn't heated by some other source in the meantime? For starters the region is very volcanically active. They might have hit an undetected hot spring or some other heat source from deep below. Also if the fault continues to move, wouldn't it cause friction in the meantime, which would heat up the clay?
Besides wouldn't drilling into the clay heat it more than just 0.31 C?
Another thing. If they measured this a year after the earthquake, then they would have measured it around marts 2012. Those measurements aren't really what I would call brand new. I know they had to examine their measurements, but great speed doesn't appear to apply to getting this result.
Most of the info is in the Nature article, the paper, though probably funded by the taxpayes, is securely behind the AAAS paywall. Maybe Congress, if it had any balls, would make it illegal to publish publically funded research behind a paywall, but I digress.
The message here seems to be that there were really two geologic events on the subduction zone of Japan's northern coast in March 2011. The first was an an ordinary subduction quake at modest depth in the plane of the Benioff Zone, a thrust event, but that was followed by a seconary event at shallower depth which involved as much as 50 meters of thrust that triggered the huge 30 m. tsamani. This latter event was triggered by the primary subduction quake in a regime that released stress in the plate by allowing for a large amount of slippage in a relatively weak medium, not storing tectonic strain by reacting to its release elsewhere.
The analogy with the San Andreas Fault in Central California is that there are incompetant rock allowing for a relatively large ammount of slippage, some of it aseismic, between segments of the fault that are stuck because of very strong rocks that store strain for release in large quakes. So serpentines in central California may more easily pas strain along toward places where hard rocks like grainites are storing the stress to be released all at once, to the north and south of the central segment of the fault/
The difference is that the release of strain at one place in the subduction zone caused even greater slip in an incompetant boundary seaward of the initial tectonic release. In California we ger fault creep, but it is not enough to release all the strain, nor does it happen in one great event. Nor does muddy subduction even always result in seismic activity. The Mariannas Trench is aseismic probably because the subduction zone is greased and not storing strain enough to result in quakes, and there are mud volcanoes in that area as well, serpentine mud has been found there.
The abstract for the paper called the grease in the Japan subduction zone "Plagic Clay". All that means is that the mud comes from clay minerals that settle out of the water column. They could have been terrigenous, sediments from land ultimately, that got carried as far as they can get, or meteoric. The "Grease" in California and in the Mariannas Trench is different. It is from a slippery mineral that forms from the reaction of water with minerals very rich in Fe, Mg and less Si, like Olivine. The Pelagic mud may not be slippy enough to release all the strain like the Marianas serpentine mud, but it may need a nudge to move, and then ti might move a great deal all at once. 50 m. is a lot.