Undersea volcanic eruptions account for more than three-quarters of volcanic activity on Earth, but their effects are rarely witnessed.
The 2022 Ha'apai eruption of the Tonga-Hunga volcano was a dramatic exception, as the explosion from shallow water breached the ocean surface, generating supercharged lighting and an atmospheric shock wave that circled the globe several times.
But the repercussions were much greater than what satellite images could capture.
Now, a new study examining the underwater effects of the Hunga-Tonga volcano eruption has detailed how powerful the explosion shook the seafloor, damaged cables, and choked marine life.
"The eruption causes dramatic changes in nutrient and oxygen levels in the water, which may have feedbacks that we don't yet understand," says lead author Sarah Seabrook, a marine biochemist at New Zealand's National Institute of Water and Atmospheric Research.
Seabrook and her colleagues compared seafloor mapping surveys conducted three months after the January 2022 eruption with data collected from the same area between 2015 and 2017.
“While ocean impacts from volcanic eruptions are usually hidden from view, we show that they can have catastrophic consequences, including widespread loss of marine life and damage to vital communications links in the ocean,” the researchers wrote in their paper. seabed, with devastating economic impacts.”
The team also compiled a wealth of data from ship-based sonar, sediment cores, geochemical analyses, water column samples, and video footage to map powerful, destructive disturbances.
“Most submarine volcanoes are not well mapped,” they wrote, describing the underwater impacts of shallow water volcanoes near inhabited islands as a “major blind spot” in risk assessment and preparedness.
Video footage showed that a large portion of the sea floor was devoid of marine life or choked in ash three months after the eruption.
But some wildlife refuges were discovered on nearby seamounts where the terrain protected the animals from the external blast.
“Future monitoring, both of the volcanic edifice itself and the seafloor and surrounding habitats, is essential to determine the ability of human and natural systems to withstand and recover from major marine eruptions,” says Seabrook.
The study was published in the journal Nature Communications.
China is developing military unmanned submarines
The Navy Recognition website reported that China is working on a project to develop military unmanned submarines.
According to the website, each of the new Chinese JARI-USV-A submarines will be 58 meters long, 23 meters wide, and its water displacement will be equivalent to 420 tons. It will be equipped with diesel and electric engines that allow it to carry out short and medium-range trips.
According to the site, these submarines have the capabilities to perform various tasks autonomously, including reconnaissance and maritime patrol tasks, and they can be modified in different ways to suit the tasks they will perform.
Available information indicates that the submarines will receive a variety of weapons, including machine guns and anti-ship missiles. They will also be equipped with torpedoes and anti-air missiles. They will be able to transport payloads weighing up to 70 tons and move at a speed of 42 knots. They will also have the ability to hide from radars. and enemy sonar devices.
These submarines will be able to operate collectively with warships and other unmanned submarines, and will be equipped with equipment for coordination and communication with naval platforms.
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