Friday, March 13, 2009

New Madrid: No Strain No Gain


In the past few years, the big glory in earthquake studies has come from real-time GPS measurements. For example, Northridge didn't have a fault rupture, but they measured that the mountains bounced up 3 m. And there have been lots of these 'slow earthquakes' that just show strain, but no seismic waves.

And so I remember, it was with great excitement that I was involved in boosting up the Southern Ontario Seismic Network with real-time GPS. I was sure it could show something around the Hamilton area. And I knew our strain rates must be about 10 times less than California, but it still should show up, especially around New Madrid.

Ah, the best laid plans of mice, and crazy guys! Now, it appears that New Madrid has come up a cropper. They're saying that it might show the old gal is dead, but I know better. Our strain energy accumulation may be 10 times less, but our rock is probably 10 times stiffer than California. Thus, we may never make any good measurements.

And now I realize that our earthquake mechanism is different from the bankrupt state. Our earthquakes come from stress corrosion at the fault resulting in strain relief. Thus, we may never read anything until there is a big earthquake. Then, I'm sure the needles will go through the roof! :)

So, keep up with the GPS measurements, and will see something soon.

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