A study shows Pumice stones are likely to continue to wash ashore in Japan into next month.
A simulation by the Japan Agency for Marine-Earth Science and Technology shows southwestern regions including Okinawa and Amami and some of the Izu Islands in the Pacific will be affected by the floating rocks.
The agency on Monday released the results of its simulation of pumice stone flows, using recent satellite data.
An underwater volcanic eruption in the Pacific in August created massive amounts of pumice stones that have been drifting ashore in Okinawa and Amami since October.
Pumice stones have also reached some of the Tokyo-administered Izu Islands, including Shikinejima and Izu Oshima this month. They were carried by the Kuroshio current.
The floating rocks also drifted onto Miyakejima and Kozushima on the Izu chain on Saturday.
The simulation shows large amounts of pumice stones will likely drift into eastern seas in early December.
The situation in Okinawa and Amami regions remains serious. Stones are expected to remain there on coasts and in surrounding waters until at least December 9, the latest date in the simulation.
The agency's senior researcher Miyama Toru indicated that there may be more stones than were shown in simulation because some were not detected by satellite. He said the stones may approach the Izu Islands continuously, so it's necessary to remain on the guard.