How freighters could help detect tsunamis
Hossen, Sheehan, and their colleagues modeled just how well a cargo-based detection network could actually work. Hossen is the first author of their paper Posted in Earth and Space Sciencee in February, evaluation of GPS forecasts of on-board tsunamis in the Cascadia subduction zone via a computer simulation. Given the regular vessel traffic in the region, the researchers used actual vessel coordinates provided by the global data and analytics provider. Arrow. While maritime traffic generally follows similar routes, the number and spatial distribution of ships varies, which the simulation took into account. The study also simulated the variations in altitude and speed of ships caused by the tsunami. The team used data assimilation, a technique that combines observations with a numerical model to improve predictions, to predict virtual tsunamis.
Assuming each ship was fitted with a GPS sensor capable of accurately measuring elevation (and therefore detecting a passing tsunami), the simulation indicated that a gap of 20 kilometers – about 12 miles – between the ships in areas with high ship density would be sufficient to be precise. forecasts and that forecasts can be made reliably within 15 minutes of the onset of the tsunami.
And that matters because the pacific coast is due for a few significant tectonic activity of pressure build-up, scientists say. “In the region of the Cascadia Subduction Zone, many studies show that a great earthquake is coming,” Hossen says. “We don’t know when and where it could trigger a tsunami.”
But this system would not be ready to work right away. While commercial vessels regularly use GPS, they don’t communicate their altitude data – exactly how much they are floating. All over the world, the automatic identification system (AIS) continuously tracks their latitude and longitude, but these broadcasts do not include altitude, as boats are likely to remain at sea level. To detect tsunamis, these slight changes in altitude should be relayed in real time, but given the ubiquity of satellite navigation, it may be possible to include this information.
“What I really liked about this method is that the method is inexpensive,” says Anne Bécel, a Lamont associate research professor at the Lamont-Doherty Earth Observatory at Columbia University, who did not participated in the CU Boulder study. “If this method were fully developed, it would become very affordable for many countries threatened by local tsunamis.”
Commercial vessels could complement, not replace, existing tsunami detection mechanisms, while offering a much more cost-effective approach than adding new seabed pressure sensors. While ships using GPS might help predict the threat of a tsunami by recording wave height, which correlates with its potential for damage, they wouldn’t necessarily sound the alarm that a tsunami had been generated, explains Foster of the University of Stuttgart. “This system will probably never be the trigger for the alarm. It will be the fact that there has been a huge earthquake that sets off the alarm, ”he says.
Yet other geological events – such as underwater landslides and volcanic eruptions – can cause tsunamis. A warning system based only on wave observations, and not on what triggered them, would be beneficial, says Sheehan, also a CIRES member. “With this method, we’re not really making any assumptions about the earthquake or the landslide or what caused the tsunami. We’re just looking at the waves as they’re recorded by the ships, so you’re using the actual observations, ”she says.
Foster says shipping companies have been very receptive to the idea of using their boats to help predict tsunamis. But before that can happen, scientists will need to do more research on the extent of the floating network that will be needed, as well as the accuracy and processing of on-board GPS data.
While the CU Boulder study relied on a simulation, adding additional data from actual ships could improve the results, Bécel says. “The next step will really have to show that with a high precision GPS, [researchers] have the same results with great precision, ”she says. “At the moment, it looks like it’s very promising.”
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