Washington: Scientists have discovered a way to identify indicators of a mega earthquake using GPS-based information, an advance that may help improve early warning systems for quakes. The researchers from University of Oregon in the US combed through databases of earthquakes since the early 1990s have discovered a possible defining moment 10-15 seconds into an event that could signal a magnitude seven or larger quake.
Likewise, that moment — gleaned from GPS data on the peak rate of acceleration of ground displacement — can indicate a smaller event. GPS picks up an initial signal of movement along a fault similar to a seismometer detecting the smallest first moments of an earthquake. Such GPS-based information potentially could enhance the value of earthquake early warning systems, said Diego Melgar, a professor in the University of Oregon.
GPS monitors exist along many land-based faults, but their use is not yet common in real time hazard monitoring. GPS data shows initial movement in centimetres, Melgar said. “As an earthquake starts to move, it would take some time for information about the motion of the fault to reach coastal stations. That delay would impact when a warning could be issued,” he said.
This delay, he added, would only be improved by sensors on the seafloor to record this early acceleration behaviour. Having these capabilities on the seafloor and monitoring data in real time, he said, could strengthen the accuracy of early warning systems.
