Scientists have registered signs of an impending earthquake 10 hours
before it occurred along California's San Andreas Fault. Seismologists
say the new, highly sensitive technology holds promise in giving those
who live in particularly deadly earthquake zones enough time to
evacuate. VOA's Jessica Berman reports.
Like most massive earthquakes, experts say the one that hit China's Sichuan province in May, 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.
But seismologists, reporting this week in the journal Nature, are using sensitive tools near Parkfield, California on the San Andreas fault to detect 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.
Niu and colleagues made direct measurements leading up to the temblors by inserting sophisticated electrical probes one kilometer into the fault that detected the tiniest stresses in rocks.
"We found these changes start about ten hours before [a] magnitude three earthquake and two hours before a magnitude one earthquake," said Fenglin Niu.
The earthquake in China was a magnitude 7.9 in intensity.
Seismologists now want to see if they can detect earthquakes with greater precision by inserting their equipment 10 kilometers into the San Andreas fault.
Niu says they are following up their experiments with seismologists in China and Japan.