Washington
09 July 2008
Scientists have registered signs of an impending earthquake 10 hoursbefore it occurred along California's San Andreas Fault. Seismologistssay the new, highly sensitive technology holds promise in giving thosewho live in particularly deadly earthquake zones enough time toevacuate. VOA's Jessica Berman reports.
Like most massiveearthquakes, experts say the one that hit China's Sichuan province inMay, killing 69,000 people, gave residents no time to evacuate.
According to experts, the most modern earthquake detection systems now in use only detect quakes seconds before the event.
Butseismologists, reporting this week in the journal Nature, are usingsensitive tools near Parkfield, California on the San Andreas fault todetect minor changes in the earth's crust prior to earthquakes.
They successfully used the equipment hours preceding two earthquakes, one on Christmas 2005 and a smaller one five days later.
Lead author Fenglin Niu is a seismologist with Rice University in Houston, Texas.
Niuand colleagues made direct measurements leading up to the temblors byinserting sophisticated electrical probes one kilometer into the faultthat detected the tiniest stresses in rocks.
"We found thesechanges start about ten hours before [a] magnitude three earthquake andtwo hours before a magnitude one earthquake," said Fenglin Niu.
The earthquake in China was a magnitude 7.9 in intensity.
Seismologistsnow want to see if they can detect earthquakes with greater precisionby inserting their equipment 10 kilometers into the San Andreas fault.
Niu says they are following up their experiments with seismologists in China and Japan.