TOKYO (AP) — Massive amounts of volcanic pumice pebbles spewed from an undersea volcano in the Pacific Ocean have been piling up on southern Japanese coasts, damaging ports and fishing boats, and prompting the central government to establish a task force to deal with the unwanted arrivals as a natural disaster, officials said.

The gray pebbles were spewed and floating from the Fukutokuokanoba undersea volcano in the Ogasawara island chain, which erupted in mid-August. The island is about 1,000 kilometers (600 miles) south of Tokyo.

Deputy Chief Cabinet Secretary Yoshihiko Isozaki told reporters Friday that the pumice pebble damages have so far affected 11 ports on Okinawa and 19 others in the Kagoshima prefecture on Japan’s southernmost island of Kyushu.

About 40 fishing boats have been damaged, including six that were unable to move, and ferry services connecting remote islands in Okinawa and Kagoshima have been temporarily suspended.

He warned that the pebbles are moving farther to the north and could affect entire Japanese coasts.

At the Kunigami village on the northern tip of Okinawa’s main island, a shovel car started scooping up the massive pebbles that filled the port like a landfill.

The government task force, at its first meeting late Thursday, decided to provide support for local municipalities as a disaster recovery project, and that damages to fishing industries will be covered by insurance, Isozaki said. The total cost of damages from the volcanic pebbles is still unknown.

Okinawa Gov. Denny Tamaki, at a prefectural task force meeting, said there has been a “huge impact on the fisheries and tourism industries as well as the environment” and that the problem must be tackled quickly.

Japan Coast Guard’s regional divisions routinely monitor the coasts and distribute photos and pebble pileup updates on a map. The Nuclear Regulation Authority also watches the pebble movements to avoid any impact on Japan’s coastal nuclear power plants.