"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."

Comments

can release as much energy

[Visaris]

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?

Re:can release as much energy

[TastyWords]

Why would kinetic energy necessarily guarantee a buildup of potential energy?

Think about standing halfway up|down a flight of stairs and you have a package sitting on the stairs and you have it on a rope. Move either way (up or down) on the stairs. Does expending this energy mean a buildup is imminent? Of course not. If you are dragging it down the stairs, as it gets closer & closer to the bottom, the available potential energy is less & less. If you drag the package up the stairs, there is an obvious buildup of energy and if you were to bump the package or accidentally tug on the rope, the energy would be released. And anyone listening (measuring) without seeing the stairs, who would hear the package moving, wouldn't necessarily know which direction it was going - unless|until they learned out to measure a difference in the acoustics.

I'm sure someone's going to shoot holes in this by claiming all sorts of exceptions or places where it doesn't work, but this is just a rough idea.

Tectonic plates

[Plaeroma]

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.

Re:I think it's scary...

[TastyWords]

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.

Encourage them!!

[sameerdesai]

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.

Re:add to or relieve stress

[geomon]

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.

Re:I'm still waiting....

[WhiteBandit]

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! :)