GPS tracking systems on commercial ships navigating the world’s oceans may be able to provide better warnings for potentially deadly tsunamis, according to a study published May 5 by scientists at the University of Hawaii – Manoa (UHM) and the National Oceanic and Atmospheric Administration’s Pacific Tsunami Warning Center.
UHM’s research ship “Kilo Moana” was on its way to Hawaii from Guam when a tsunami was generated by an 8.8 earthquake in Chile back in February 2010. The Kilo Moana is equipped with an advanced GPS tracking system and the data it recorded mirrored the tsunami predictions from the Pacific Tsunami Warning Center. This is the first time a ship has ever detected a tsunami.
A highly sensitive geodetic GPS tracking system onboard Kilo Moana detected the tsunami even though it was only 9.4 cm high as it passed under the ship, as reported in a paper in Geophysical Research Letters (GRL). This finding came as a surprise because tsunamis have such small amplitudes in the deep water, in contrast to their size when they reach the coastline, that it seemed unlikely that the tsunami would be detected using GPS unless the ship was very close to the source and the tsunami was very big.
Foster and co-authors estimate that this sort of ship-based tracking system would have been able to detect the 2004 Indian Ocean tsunami within an hour, potentially saving thousands of lives. A tracking system installed on commercial ships could “improve our detection and predictions of tsunamis — saving lives and money,” said Dr. James Foster of SOEST.
Given the affordability of geodetic GPS tracking systems, and ever-improving satellite communications, it would be possible to equip a significant portion of the shipping fleet with real-time-streamed GPS tracking systems and create a cost-effective tsunami monitoring network with denser and more distributed coverage. “Our discovery indicates that the vast fleet of commercial ships traveling the ocean each day could become a network of accurate tsunami sensors,” Foster said.
Foster and his colleagues are now working on developing a network of commercial ships equipped with the geodetic GPS tracking system that could become the next phase in real-time tsunami warning in the Pacific. “There are so many ships out there that if you’ve got enough of them instrumented with the GPS tracking systems there is always going to be some ships in the neighborhood of the region that produces the tsunami,” said Foster.
Much more advanced than a handheld GPS device, the GPS tracking system on a ship would include a round antenna to help measure and transmit even the slightest wave height changes from a tsunami that would likely go unnoticed in the open ocean. The difference being measured in length of time.
“An open ocean swell has a period of maybe 15 seconds, 20 seconds. A tsunami takes maybe 20 minutes, half an hour to pass,” said Foster.
At $15,000 to $20,000 per unit, the GPS tracking system is cheaper than the current deep ocean buoys that provide tsunami data. The challenge will be getting the commercial shipping lines to jump on board to create a mobile tsunami detection system.
UH researchers hope to launch a demo system with at least two ships by the end of the year.
Source: University of Hawaii – SOEST