Seeding the ocean with pressure sensors to detect tsunamis before they strike can be expensive and time consuming. But it might be possible to fill in gaps in the sensor network using existing communications cables.
Researchers at the National Oceanic and Atmospheric Administration and the University of Colorado have developed computer models that show that the displacement of sea water during a tsunami generates electrical voltage as it moves through the earth’s magnetic field (it’s the same principle by which a magnet moving past a coil in a dynamo generates electricity). The models suggest the voltage produced in underwater cables would be about 500 millivolts, large enough to detect. The voltage is created in the copper wires that typically accompany fiber optics, says Manaj Nair, the research scientist at NOAA and the University of Colorado, who led the work.