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"Slow" Earthquakes May Help Predict Major Quakes
Iphtashu Fitz writes "Think all earthquakes last only seconds or minutes? Think again! Scientists at the University of Washington are measuring a "slow" earthquake some 12 to 25 miles underground that could last as long as a month. Along with the UW scientists, seismologists at the Geological Survey of Canada and Central Washington University have documented at least nine previous so-called slow earthquakes going back to 1992. They seem to occur every 14 months or so, the last one occuring in February and March of last year. These earthquakes, also known as slow-slip earthqakes, can release as much energy as a magnitude 6.8 earthquake but because it's released over such a long period of time nobody on the surface even notices it. One key question the scientists are trying to answer is whether these slow earthquakes add to or relieve stress in the tectonic plates, which could ultimately help to predict major earthqakes."
These earthquakes, also known as slow-slip earthqakes, can release as much energy as a magnitude 6.8
Does this not imply stress is being released?
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is it possible to extract any energy from these massive events ? or are they too un-reliable and too much energy would be required to make harnessing it woth while ?
AJS
ever mentions the fault line that runs along the Mississippi river? Didn't a major quake in the recent past cause the river to run backwards?
"I'm just here to regulate funkiness."
Can someone explain to me the difference in a 'slow earthquake' and just general plate movement? Cause from I just read, I couldn't differentiate between the two.
You want scary?
Here in the midwest (Indiana) we're anxiously awaiting the next quake from the New Madrid fault. The last time it peaked, the Mississippi reversed direction for two days and the ground rippled like waves of four-to-five feet.
Imagine that with the fact most buildings in the midwest, whether it's Chicago, St. Louis, any other city familiar to you - if you aren't familiar with all of the cities, haven't been built to withstand an earthquake. After all, they don't come along often enough to warrant that type of concern and|or expense.
One key question the scientists are trying to answer is whether these slow earthquakes add to or relieve stress in the tectonic plates, which could ultimately help to predict major earthqakes."
Knowing nothing about Earthquakes, naturally i have an opinion.
any time you have irregular shaped objects moving in oposite directions against each other you are going to have a transfer of "stres" from various points along the "fault line" so, while stress is removed from one location it is usually only getting transfered to somewhere else. point being the pressure (therefor the stress) which in reality is due to things like "gravity" is always going to be there, (at least lets hope it does)
The fact that the are now able to detect lower frequencies with more accurate tools, is however great news for anybody who wants to try and predict when things are going to get violent in terms of earthquakes.
Just some guesses:
A "slow" quake could release stress along a certain section of the plates, but build up pressure along another section further away - thus leading to a large quake along the second section.
A "slow" quake could ramp up to a large quake if the slippage reaches a point where the plates have less friction against each other.
The faults don't only shift when a major earthquake occurs. A "slow" quake may shift the two plates closer to a point that can only shift through a large quake.
Obviously, IANAS or IANAG - and as neither scientist nor geologist - these are mere guesses based on what I do know of earthquakes.
I was taking one day at a time, but then several days got together and ambushed me. (from a Rhymes with Orange comic)
I believe a research into predicting earthquakes should be encouraged and given more funding. I am saying this because of my own experience. About 3 years ago, my city and lot of cities around my state experienced a major quake reading 7.8 (Bhuj quake in India) that killed more than 30,000 people. I was sleeping when this happened and it was terrifying. Never in my dream I had imagined my city was in earthquake prone zone. Looking at the rumble and bodies gave me shivers. I believe if such a thing is developed so many lives could be saved (if not property). Also this might help in identifying earthquake zones (if I remeber correctly they classify them in zones based on likelihood of having an earthquake) and that can give an impetus to civil authorities to build earthquake proof houses minimising property damage as well. Just my thoughts.
Yes, the stress relieved at one site may be trasferred to another along the plate margin. But exactly where in the system it is taken up determines whether the "receiving" plate margin will react in a catastrophic manner. Some sites may behave in a plastic (quasi-elastic) fashion and the stress will be dissapated in a slowly developing folded crust. Others will absorb the stress along brittle margins and will eventually react in a non-elastic fault.
"Rocky Rococo, at your cervix!"
One key question the scientists are trying to answer is whether these slow earthquakes add to or relieve stress in the tectonic plates
I am by no means a geologist, but I'd speculate that the slow earthquakes (maybe earthquakes in general?) add stress to some plates and relieve stress in others, somewhat similar to the law of conservation of mass in physical science. That energy has to go somewhere...
If you've lived in Seattle, you know that the entire state is a major earthquake zone. I live in Southern California now (lancaster), but I had some fun in the last few major quakes we had there. It's common knowledge up there that the beautiful Cascade Mountains are almost all active volcanos, the rivers flood annually, the windstorms are irritating, and the earthquakes are generally in the range of 3-4.5 if you can feel them.
The geologists up there keep saying that Washington State is due for a huge magnitude quake, something on the order of 8.0. There are also fault lines crisscrossing the Seattle area, Puget Sound, and the outlying areas.
BTW, I read somewhere that a researcher had derived a quake prediction scheme based on seismic data. The scheme has been very accurate so far, but I can't for the life of me remember where I read it. I think it was Scientific American. But the guy predicts a 6.0+ quake in Mojave this fall.
Dr. Keilis-Borok at UCLA and his team are claiming to have predicted two earthquakes. One in Japan as well as the one in San Simeon.
:)
Using similiar techniques, they are prediciting an earthquake of a minimum magnitude 6.5 in the Southern California desert by September 5. It will be interesting to see if this pans out.
Interestingly enough, I am have an internship in seisomology with the So. Cal. Earthquake Center this summer and will be working at UCLA. I have a feeling it is going to be quite busy!
> What's even more interesting is that I have yet
> to see any reports about this coming from any of
> the California plates, perhaps it hasn't been
> found or tested for or it's just not there..
> Who knows.
California's tectonics are significantly different than the OR-WA-BC situation. The Subduction Zone we have up here in the Silicon Forest puts us at much greater risk of The Big One.
An Oregon Department of Geology scientist gave a Tsunami presentation at my Red Cross Disaster Responder meeting earlier this month. She reviewed the history of Tsunamis and the quakes which cause them, at the Oregon shore. Layers of sediment show when there's been a big one. She, and the rest of the department, based on the physical evidence and frequency, think there's one due 'soon'.
Seaside would NOT be a good place to be, ditto for Gold Beach and Florence. If your oceanfront community does NOT have evac routes already plotted, and signage posted, right now, then consider moving.
At very least, go to the ODG website and get the evacuation brochures.
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I have to disagree. I believe the composition of the soil here in Memphis is such that liquifaction would occur to a much greater severity than expected or planned for. Although Jackson, Tn was hard-hit by at "least" 2 tornadoes last year, that is but one relatively small area compared to the new madrid area as a whole. There was a strong F2 in Dyersburg and another smaller one in Covington last year, but nothing that has wiped out so many homes that they've all been rebuilt. A drive up Highway 51 from Memphis to Covington would be an easy way to illustrate that fact. The tornado in Memphis occured last year during the BBQ World Championships, and came right through Tom Lee park, where I was scarfing down BBQ, but was really only a funnel cloud that didn't touch down. There "were", however, a LOT of strong straight-line winds that caused some major damage...Again though, nothing that could come close to the damage of an 8.0+ quake. I,myself am less worried about the new Madrid than the Yellowstone Caldera...It's probably the only "disaster scenario" in the continental US that would exceed an 8.0+ New Madrid quake
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