Interesting correlation: Decade long Geo-markers (earth's daily heart beats)that predict giant mega (8.0+) earthquakes. With the recent quakes in Haiti and Chile, this story has some direct applications.
According to a AAAS press release:
"Tidal forces may have contributed to triggering the devastating magnitude 9.0 Sumatra earthquake of 2004 and other large earthquakes in the region. Gravitational pull from the Sun and the Moon not only is responsible for ocean tides but also creates Earth tides, slight motions of the solid Earth (bulges and dips in the earth's crust and upper mantle) that can lead to stress buildup (or stress relief) along faults.
[N.B. The earth experiences about 1000 earthquakes per day, of which 800 are not perceptable - I call it the earth's many heart beats.(bet you didn't know that) --Walter Derzko].
Earth tides cause tiny variations in the stress on faults, but it isn't clear whether this stress could be enough to trigger an earthquake. Although the motion due to tidal forces is small, small stresses can accumulate on a fault. To determine whether earthquake occurrences off the coast of Sumatra correlate with an Earth tide phase, Tanaka carries out a simple statistical analysis. The phase of the tide determines whether the Earth moves in a direction that adds stress to a fault or relieves stress. The author finds a strong correlation between earthquakes and Earth tide phase in the decade before each megaquake, providing evidence that Earth tides can indeed induce an earthquake on a fault that is already critically stressed.
In summary: more tremors occurred when the pull of daily "earth tides" was at its strongest than at other times ( as predicted by American geologist Jim Berkland).
She suggests that monitoring Earth tides might provide information that could improve earthquake forecasting.
So future weather forecasts might not only warn us of high tides but high earth tides too.
See related post: Predicting or triggering earthquakes, volcanoes or other natural disasters.
Source: Tidal triggering of earthquakes precursory to the recent Sumatra megathrust earthquakes of 26 December 2004 (magnitude 9.0), 28 March 2005 (magnitude 8.6), and 12 September 2007 (magnitude 8.5) by Sachiko Tanaka: National Research Institute for Earth Science and Disaster Prevention, Tsukuba, Japan. Journal: Geophysical Research Letters (GRL) paper 10.1029/2009GL041581, 2009 http://dx.doi.org/10.1029/2009GL041581
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Walter Derzko, Smart Economy, Toronto
Author of the soon-to-be published book- Opportunity 45 Scenarios to Drive Your Business in Challenging Times, published by J. Wiley and Sons ISBN13: 978-0-470-73761-3 ISBN10: 0-470-73761-1
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