Pattern of waves generated by the 2011 Japan tsunami. Image credit: NOAA
Unfortunately, as Dr. Andreas Hoechner, lead author of the German Research Centre for Geosciences team points out, such information has not always been accurate.
In the case of the 2011 Japanese tsunami “the first warning, based on traditional seismological methods, underestimated the earthquake size by a factor of more than 30 (magnitude 7.9 instead of 9.0 on the logarithmic moment magnitude scale),” he told Decoded Science.
Using Satellite Global Positioning Systems (GPS)
So, what’s the answer to improving warnings? To give an accurate estimate of arrival times, scientists need to know, as accurately as possible, both the magnitude and location of the earthquake. The study suggests that the answer lies in the use of satellite-based global positioning systems (GPS).
By using the example of the 2011 tsunami and simulating its progress using real-time raw data, the team were able to demonstrate that it would have been possible to generate an accurate reading for the earthquake within three minutes, allowing the authorities to identify and evacuate areas at risk.
Practical Applications: a Future for Tsunami Warnings
Although GPS itself is not new – and, indeed, is already used in the DART buoys – Dr. Hoechner tells us that “high-precision real-time GPS processing on the order of centimetres and seconds has become available only in the last years.” Further, the GPS networks which do exist have yet to be integrated into the planet’s rapidly-improving tsunami warning systems.
Dr. Hoechner believes that the modelling undertaken in the study shows that GPS can make up for the shortcomings of the existing system: there are already existing stations in Japan and elsewhere which can supply the data. As for the practical application, he sees little problem there either. “The cost of the technical parts of the stations is actually not too high and should be affordable for most if not all affected countries. Maintenance and stable supply of power and communication, especially for remote areas, is maybe more of a challenge.”
DART tsunami warning buoy. Image credit: NOAA
Tsunami Warning System: Fast Reactions Save Lives
Of course, a tsunami warning is not in itself enough: the reaction of the authorities and the local populace is also vital. We can’t know for certain how many lives would have been saved in Japan had the GPS data been integrated into the tsunami warning system, but it does seem likely that a more accurate indication of the area at risk would have been achieved.
Sources
NOAA Center for Tsunami Research. DART® (Deep-ocean Assessment and Reporting of Tsunamis). Accessed May 19, 2013
Hoechner, A., Ge, M., Babeyko, A.Y. and Sobolev, S.V. Instant tsunami early warning based on real-time GPS – Tohoku 2011 case study. (2013). Natural Hazards and Earth System Science. Accessed May 19, 2013
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