G&T Linking Earthquakes

Trigger science links Samoa tsunami to Sumatra quake
THE frightening possibility that the Samoan earthquake helped trigger the Sumatran earthquakes has been raised by scientific research.
Until the American study, experts accepted major earthquakes happening close in time but far apart, was coincidence.
But the new theory, by seismologists at the Carnegie Institution in Washington, says a large earthquake might cause earthquakes thousands of kilometres away.
The seismologists investigated a 1992 California earthquake and the devastating 2004 Sumatra earthquake - and their impact on the San Andreas fault in California.
Both quakes caused seismic waves of energy to move through fluids in the fractures within the fault.
The scientists detected an increase in small earthquakes along the fault after the fluids were disturbed.
But a Melbourne geologist said the only connection between the Samoan and Sumatran quakes was that both were on the Rim of Fire.
" The faultlines run from New Zealand to Samoa to Papua New Guinea and on into Indonesia, Japan and the US west coast: the Rim of Fire," Dr Bernie Joyce, of Melbourne University, said. The moving fluids " lubricated" the San Andreas fault, which weakened it and made it prone to slipping.
Slipping, along with a build-up of pressure between plates, are the two main causes of earthquakes.
The scientists detected an increase in small earthquakes along the San Andreas fault after the fluids were disturbed by the distant quakes.
" So it is possible that the strength of faults and earthquake risk is affected by seismic events on the other side of the world," one of the study's authors, Fenglin Niu, said.
The Carnegie research, published in the journal Nature yesterday, may help the hunt to find a way to predict earthquakes.

G&T Linking Earthquakes

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