Detecting earthquakes with GPS

Nature : An earthquake warning system is being developed based on satellite data from the global positioning system (GPS), writes Richard Lovett for Nature. NASA and a group of universities called the READI network are testing the system using the US Pacific Northwest Geodetic Array, which consists of hundreds of GPS receivers spread out along the Pacific coast between Northern California and British Columbia. When seismic waves travel from faults toward populated areas, they first hit the sensors, which trigger a warning message and give officials a few seconds’ notice. Although conventional seismometers provide similar information, the researchers found that GPS measures the degree of ground shaking more accurately and thus provides better information about a quake’s magnitude. In March 2011 the reliance of Japanese officials on seismometers led them to underestimate the magnitude of the impending quake and the size of the subsequent tsunami.