Seattle, US: Once the Pacific Northwest Geodetic Array’s (PANGA) “real-time” functions get fully operational, it will be able to pinpoint some earthquakes more quickly and accurately than traditional seismometers — and eventually issue warnings before destructive shaking hits cities or tsunami waves slam the shore, claimed Tim Melbourne, Director of the PANGA.
“If the Pacific Coast or Mount Rainier moves a couple of centimetres, we’ll see it within five seconds,” said Tim, a geology professor at Central Washington University in Ellensburg, where PANGA is based.
PANGA’s instruments are sophisticated variations on consumer GPS units, using the same constellation of satellites to triangulate positions. Scientists use the GPS data to calculate the gradual build-up of strain on faults and identify the places most likely to pop. Dozens of the sensors also sit atop structures such as the Alaskan Way Viaduct and Howard Hanson Dam, on watch for unexpected slumps or jiggles.
Today, 450 GPS units span the region, spitting out readings every second. Operating in peak mode, PANGA can track ground motions as tiny as one-tenth of a millimetre.
GPS networks have revolutionized the study of geology by opening a window onto the tectonic forces that shape the landscape and underlie earthquakes and volcanism. Recently, using a combination of GPS and sonar, Japanese scientists measured nearly 80 feet of slip on the underwater fault that triggered the quake and deadly tsunami.
GPS measurements also were key to the recent discovery of “silent” earthquakes that occur roughly every 14 months deep within the fault called the Cascadia Subduction Zone, where the seafloor dives under the continent. Running along the coast from Vancouver Island to Northern California, the fault has unleashed some of the world’s biggest quakes — most recently a magnitude 9 in 1700.
Until now, PANGA’s main application has been for research. But the ability to record motion instantaneously, made possible by a grant from NASA, is turning the network into a tool with practical uses.
Source: Seattle Times