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UC Berkeley study ties 2004 Sumatra quake to California temblors

Researchers analyzed 20 years of data in the Parkfield area and found that the 2004 earthquake weakened the San Andreas fault, changing the frequency and strength of quakes in the area.

October 03, 2009|Raja Abdulrahim

The 2004 Sumatra earthquake that set off a deadly tsunami also seems to have caused more earthquakes along the San Andreas fault in the last few years, according to a study from UC Berkeley.

The study analyzed 20 years of data in the Parkfield area, which sits on the fault, and found that the disastrous earthquake weakened the fault, changing both the frequency and strength of earthquakes in the area.

"So you will have many earthquakes, but the magnitude will be smaller than expected," said Taka'aki Taira, a seismologist at UC Berkeley who headed the study.

Similar small earthquakes followed the 1992 Landers earthquake in San Bernardino County, the study found.

David Shelly, a seismologist with the U.S. Geological Survey, said the study's conclusions are speculative. "The effects from the Sumatra earthquake are fairly subtle and it's not entirely clear how widespread it might be," he said.

Taira acknowledged that the study's scope is limited and researchers are continuing to look at more data. Whether the Sumatra quake affected other parts of the world, he said, is "still an open question."


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