A consortium led by Mitsubishi Heavy Industries Ltd. and Nippon Steel & Sumitomo Metal Corp.’s engineering unit has been formed with the aim of reviving Japan’s offshore mining activities.

Bloomberg reported that Japan, which first began hunting for minerals from the ocean floor, is looking for ways to source its own minerals. The consortium plans to conduct a pilot mining and lifting of ore at the Izena sea hole in the area off the southern island of Okinawa in the next financial year starting April 1. Japan has confirmed the deposit has about 7.4 million tons of ore, twice what was detected just three years ago.

New technologies have nade it easier for companies like Canada’s Nautilus Minerals Inc. to collect mineral-rich rock from the sea. With more than 50 million tons of ore estimated in Japanese waters, the government wants to revive home-grown supply and ease dependence on imports. By the time Tokyo hosts the 2020 Olympics, bullion for gold medals may come from the offshore sources.

“Disruption of metal supplies may occur in the near future,” said Tetsuro Urabe, a geologist who is director of the government’s Next-Generation Technology for Ocean Resources Exploration Program. “We don’t want to be in a panic when we are confronted with a copper crisis. Unless we develop various kinds of new technology in advance, we won’t be ready for launch when needed.”

Japan is nestled in the Pacific Basin along a line of volcanoes and fault lines known as the “Ring of Fire,” a region prone to earthquakes and eruptions. When that volcanic activity occurs in the sea, magma pushes up from the Earth’s crust. After it cools, the deposits contain minerals in far greater concentrations than those dug from the land. In the blackness of the deep ocean, engineers have used remote-controlled robots and special sensors to search the sea floor for the most promising deposits.

As the world’s third-biggest economy and a major importer of everything from iron ore to oil, Japan wants to exploit its rights to access sea-based mineral ores that one domestic industry group estimates may be worth ¥80 trillion. Under international maritime law, Japan holds sway over the area 200 nautical miles from its shores, constituting the world’s sixth-largest exclusive economic zone.

Others also are trying to mine seabed ore in waters near China, South Korea and North America. So far, there is no commercial production, though Toronto-based Nautilus has a project underway off of Papua New Guinea, where the company plans to start mining gold and copper in the first quarter of 2018.

“New deposits have begun to be found one after another,” said Mitsuya Hirokawa, deputy director-general at the metals mining technology department of Japan Oil, Gas & Metals National Corp. (JOGMEC), the state-run company that helps secure energy and mineral supplies and is providing support for the sea-bed venture. The area off Okinawa shows some of the “greatest potential,” Hirokawa said.

Nautilus Minerals, in a 2010 study, estimated it will cost about $480 million to build a seafloor production system at its Solwara 1 project in 1,600 m (1 mile) of water off Papua New Guinea. That compares with about $1.5 billion-$2 billion for a similar project on land, the company said. It will cost about $70 a ton to extract the ore, which would contain on average 7 percent copper and 6 grams of gold, John Elias, a company spokesman, said in an email.