American scientists are ready to launch an experiment that might allow them to predict earthquakes before the strike, and in return, potentially save hundreds of thousands of lives. The researchers believe that a rise in static electricity below the ground could be a reliable indicator that an earthquake is immiment.
Tom Bleier, a satellite engineer with QuakeFinder, has already spent millions putting magnetometers, or special measuring equipment, along fault lines in California, Peru, Taiwan and Greece. These instruments are sensitive enough to detect magnetic pulses from electrical discharges up to 10 miles away, which may give people enough time to get to safety before a quake strikes.
Over the years, scientists have attempted to use a wide variety of methods and theories to make earthquake forecasts, and without much success. Changes in the weather, seismograms, and animal behavior have all proven not be as reliable as many once though.
Scientists now theorize that when an earthquake is imminent, activity below ground goes through a "strange change", producing intense electrical currents. At a meeting of the American Geophysical Union in San Francisco, Bleier said:
"These currents are huge. They're on the order of 100,000 amperes for a magnitude 6 earthquake and a million amperes for a magnitude 7. It's almost like lightning, underground."
Speaking with National Geographic, he added that:
"In a typical day along the San Andreas fault, you might see ten pulses per day. The fault is always moving, grinding, snapping, and crackling."
Bleier says that before a large earthquake, the background level of static-electricity discharges should rise sharply. This is what he claims to have seen prior to the half dozen magnitude 5 and 6 earthquakes whose precursors he has been able to monitor. He noted:
"It goes up to maybe 150 or 200 pulses a day."
Bleier says that the number of pulses seem to surge about two weeks before the earthquake, and then drop back to background level until shortly before the fault slips.
There are some potential snags though. Magnetic pulses could be caused by a number of other things, ranging from solar flares to lightning, random events within the earth, and even electrical interference from highway equipment.
To combat this and other issues, special ion sensors have been added to the equipment. This is because ions, or charged particles, from deep below the earth migrate to the surface and impair the accuracy of the equipment. Because the ion count can also be magnified by wet weather, humidity sensors have also been added to the equipment so that they can rule out the possibility of false alarms.
Bleier and his team of scientists have not yet monitored enough large earthquakes for him to be 100% sure that what he has found holds true for all earthquakes. However, he does believe that he has enough good clues to move forward.
Beginning in January, Bleier and his team will try to start making forecasts.
A number of other scientists are also contributing laboratory analysis to support the magnetic field theory.
Robert Dahlgren, an electrical engineer at the SETI Institute, has spent 16 months working with other scientists to squeeze rocks under high pressures to see if they produce electrical currents. He found that they do produce pressure-dependent current and voltage signals, but did not find discharges from rocks soaked in the type of brine found at earthquake epicenter depths, presumably because the salty brine short circuits the current.