An oceangoing robot that watches for tsunamis may be just the thing to save lives when disaster is on its way.
That’s the vision Japanese researchers are about to carry out around the new volcanic island of Nishinoshima. Since it emerged from the waves in 2013, the island has erupted repeatedly, posing a threat, mostly from undersea landslides, to inhabited islands nearby.
In October, Hiroko Sugioka at Kobe University sailed her invention—an autonomous Wave Glider robot outfitted with a hydrophone, microphone, time-lapse camera, and satellite uplink—off Nishinoshima in a short test cruise. Made by Liquid Robotics, the robot harnesses wave and solar power to function at sea for up to a year without fuel. Sugioka’s version is designed to communicate with a sensor package on the ocean floor, which looks for changes in water pressure and magnetic fields that indicate a tsunami has formed. This allows a tsunami center on land to get out a warning within three to four minutes of detection—enough time for people to seek higher ground.
One of the chief advantages of the system, as Sugioka told Scientific American, is its cost-effectiveness. Deep-sea tsunami detection buoys can also relay that information quickly via satellite uplink. But they require many kilometers of cable to tether the buoys to the sea floor, which Sugioka estimates makes them 10 times as expensive as her system.
Cost has certainly been a factor in whether buoys do their job. In March 2016, a magnitude 7.8 earthquake struck off Sumatra. A network of buoys in the region mostly failed to provide readings on whether a wave had been generated or how big it was. As a result, Indonesian authorities had to issue a blanket warning based on seismic readings from the earthquake. Hundreds of thousands of people fled, waiting for hours to see whether a monster wave would come ashore. It never did.
In Japan, memories are still fresh from the magnitude 9.0 Tohoku earthquake, which in 2011 spawned a massive tsunami that was badly misforecast. Sugioka plans to have her robot begin full-time monitoring of Nishinoshima in May. If tests go well, the system could be replicated and deployed wherever the threat of a tsunami lurks.