Quakes can weaken fault zones worldwide

Source United Press International

U.S. scientists studying the giant 2004 earthquake that caused Indian Ocean tsunamis say they've determined the quake weakened part of the San Andreas Fault. The seismologists said their findings suggest the Earth's largest earthquakes can weaken fault zones worldwide and might trigger periods of increased global seismic activity. "An unusually high number of magnitude 8 earthquakes occurred worldwide in 2005 and 2006," said Rice University Associate Professor Fenglin Niu, one of the study's authors. "There has been speculation that these were somehow triggered by the Sumatran-Andaman earthquake that occurred Dec. 26, 2004, but this is the first direct evidence that the quake could change fault strength of a fault remotely."