How can the new technology predict the coming earthquake?

Currently, the most modern systems for predicting earthquakes find them only a short time before the event. Like most strong earthquakes, the one that hit southwestern China in May was not identified early enough for people to flee the area. That earthquake killed sixty-nine thousand people.
    But scientists who study earthquakes are reporting that new technology could measure very small changes below ground in the Earth’s surface. Their report was published in September in Nature magazine.
    Fenglin Niu is an earthquake expert with Rice University in Houston, Texas. He and his team performed experiments along California’s San Andreas Fault, an area famous for its many earthquakes.
    The team placed highly sensitive electrical devices about one kilometer below ground in two different places. The devices were able to measure even small changes in air pressure below ground. The scientists say such changes are caused when rocks push together, forcing air out of small cracks in the rock. When this happens, earthquake waves travel faster than usual through the rock.
    The experiment was performed near Parkfield, California. Two earthquakes hit the area in late two thousand five. The first took place on December twenty- fifth. A smaller earthquake struck five days later.
    The scientists noted changes below ground about ten hours before the first quake struck. That quake measured three in intensity. They then found similar changes taking place two hours before the other quake struck five days later.
    The earthquake in China rated seven point nine in intensity. If additional tests confirm the changes are linked to earthquakes, the scientists believe their equipment could be used for early warning systems. A system that provides a signal ten hours before a major earthquake could help move people from the area and save lives.
    The scientists now hope they can find earthquakes with even greater intensity by placing their equipment deeper in the ground.