From the WSJ today.
Seismologists have revived a longstanding question in the wake of recent earthquakes: Can a giant temblor in one location trigger another large one thousands of miles away?
A new study provides the first compelling evidence that such big, distant events—which may appear to be linked when they occur within months of each other—are likely not connected at all.
"A big quake rings the earth like a bell and can trigger little quakes" halfway across the planet, said Tom Parsons, geophysicist at the U.S. Geological Survey in Menlo Park, Calif., and co-author of the study just published in the journal Nature Geoscience. "But apparently it doesn’t trigger other big quakes" over such great distances.
Geophysicists have long known that major quakes unleash bursts of energy that travel around the globe in uncertain ways. But now some scientists speculate that only sustained pressure can significantly move fault lines and thus trigger other large temblors. In addition, energy dissipates as it travels, so quakes pack a much weaker punch by the time their shockwaves reach a fault line far away.
Scientists have debated the issue going back at least to 1906, when an 8.0-magnitude temblor hit the Aleutian Islands in the northern Pacific, and just 30 minutes later, a 8.0-magnitude quake struck Chile….