By studying seismographs from the earthquake that hit Chile last February, earth scientists at the Georgia Institute of Technology have found a statistically significant increase of microearthquakes in central California in the first few hours after the main shock. The observation provides an additional support that seismic waves from distant earthquakes could also trigger seismic events on the other side of the earth. The results may be found online in the journalGeophysical Research Letters.
It has been well known that microearthquakes can be triggered instantaneously by distant earthquakes. However, sometimes the triggered events could occur long after the passage of the direct surface waves that take the shortest path on the earth surface. There are several other explanations out there about how such delayed triggering occurs. Some involve the redistribution of pore fluids and triggered aseismic creep, while others simply consider them as aftershocks of the directly triggered events. But the group from Georgia Tech found something different.
http://www.gatech.edu/newsroom/release.html?nid=64623
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