Recent volcanic eruptions on St. Vincent and Iceland caused no direct fatalities because they were predicted in advance, which is mainly possible because it’s easy for people to see a large volcano, and for its rumblings to be felt. Underwater seismic activity which can trigger tsunamis that devastate coastal areas (such as Sumatra in 2004 and Japan in 2011) is much harder to detect, which is part of why they can be so deadly.
Researchers at the University of Athens are developing underwater drones that detect radiation, which they believe could help build an early warning system for tsunamis.
On land, increased seismic activity is known to release small quantities of radon, a naturally occurring radioactive gas, into soil in the days before earthquakes happen. So detecting a spike in radioactivity in the sea floor might be able to help us predict underwater earthquakes. Except, as with lots of ocean science, we have almost no idea what’s going on with radioactivity on the seafloor, and to be able to detect a spike in radioactivity, we’d need to have baseline readings.
“Radioactivity itself is largely unknown in the marine environment, despite its importance” said Professor Theo J. Mertzimekis at the University of Athens. He’s leading a team with funding from the EU to develop underwater drones that can measure marine radioactivity. The 4 year project just started this spring. The team are currently very much still in labs on dry land, developing the sensors and A.I. the drones will need to operate.
Measuring anything on the seafloor is tough. Electronics don’t like water, and it’s a physically demanding place, with high pressures and unpredictable forces like waves and currents. Seismographs—the wiggling pens on paper in disaster movies that help us detect earthquakes—are less reliable underwater, where vibrations from the sea’s waves and winds can drown out vibrations from brewing earthquakes.
Professor Mertzimekis compares the project to NASA’s Perseverance rover, currently exploring the surface of Mars, in terms of the technological challenges needed.
The drone project has been called “RAMONES,” which is both short for “RadioActivity Monitoring in Ocean EcoSystems” and also a tribute to Prof Mertzimekis and his colleagues’ love of old-school punk and it’s ethos. “We think that we share the [band’s] mentality for new and progressive stuff,” he said in an email. Instead of having the drones require a remote pilot on a nearby research ship or shoreside facility, they are hoping to make their drones autonomous, which would drastically speed up and simplify data collection. Vehicle autonomy on land is already a challenge, but at sea it has complexities of its own. The artificial intelligence needed to power autonomous vehicles is very hungry for electricity, so the team needs to develop computers and types of A.I. that can do the job with the lowest electricity demands possible. The other issue is that most currently available radioactivity sensors are designed for a relatively peaceful life on land, so the RAMONES team are having to redesign them to cope with life near the seabed.
It isn’t just seismic activity that the researchers are looking for with the submersible drones. Human activity is increasingly altering radioactivity in the seafloor. There’s thin layers of cesium-137 which built up in the 1950-60s as a byproduct of nuclear weapons testing; there’s radon gas, which gets released from the crust by underwater oil drilling, and nuclear waste – which was dumped in the ocean from 1946 until an international treaty finally outlawed it in 1993. The consequences of over 4 decades of dropping nuclear waste in the sea is still a bit of a mystery, “The situation at sea is not fully known as lots of legacy waste is out there, but no monitoring has been available.” says Mertzimekis. The team hopes their drones might be able to help coastal communities and environmental monitoring groups keep track of this better.
In a darkly ironic coincidence this spring, the Japanese government approved the dumping of over a million tons of radioactive water from the Fukushima Daiichi nuclear disaster 3 weeks after the RAMONES project officially started. The move has been criticised by many of Japan's maritime neighbours specifically because radioactivity in oceans and on ocean ecosystems is not well understood, although several of the critical countries have bad track records when it comes to releasing radioactivity into the sea themselves. The Fukushima disaster itself was caused by underwater seismic activity, the power plant had been able to withstand the earthquake—which it had been able to detect and shut down in time for—but was catastrophically damaged by the hard-to-predict tsunami that followed. As humanity increasingly relies on the sea, we need to better understand what’s going with its radioactivity.