In relatively small earthquakes that is correct, in fact what is happening is a series of invidual small quakes. In major earthquakes the energy is released very suddenly when the fault planes can no longer contain the stress built up in the rocks on either side of them. The sudden release of energy is what makes earthquakes so damaging.
Maybe I have been watching too much TV, but I thought that was the point of having seismic stations monitoring known areas...to provide a warning of a major quake by reading the lesser ones that might lead up to the big one.
Thats the theory......but the link between smaller quakes and large ones is not yet proven, especially in areas prone to earthquake actvity (e.g. Japan, New Zealand, west coast of the US which all lie on or close too the Pacific plate boundary). If we could predict them, we could have avoided the devastation and loss of life as occurred in the recent earthquake off the coast of Japan.
I don't imagine that my distance makes me safe, but I'm glad that I don't live in Sparks. I wonder what kind of damage that they might have had?
On the Richter Scale, it might be a minor quake, but it is the strongest one ever reported in Oklahoma:
5.6 magnitude earthquake shakes Oklahoma | NewsOK.com
Unfortunately, foreshocks aren't reliable methods of predicting a major quake event, hence they are largely disregarded, especially in areas where quakes pose hazards, such as areas on the Pacific plate boundary where foreshocks can be a daily occurence. It would not be practical for evacuations to happen every time a minor quake is classified as a foreshock - in some places this could be weekly, possibly even daily.
Personally never mentioned foreshocks being a valid method of prediction. Merely was a counter to "In a major earthquake there are no small precursor quakes", which isn't entirely an absolute.
I'm not wishing to start an argument, just adding more to the discussion Airbot. I'm a geologist by profession so just trying to add some of my insight into a topic that is of interest to me.
Regards,
Golden
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