Scientists in the Philippines say they have found what appear to be pumice stones from a Japanese undersea volcano washing ashore on an island of the country's north.
The volcano, Fukutoku Okanoba, near the Ogasawara island chain in the Pacific Ocean, erupted in August.
The Philippine Institute of Volcanology and Seismology says many pumice stones were found along the coast of Batan Island in the northern province of Batanes, near Taiwan, through early this week.
The institute says it does not know precisely how far the pumice stones are washing ashore nor their number.
The footage taken by a local government official shows dark grey pumice stones spreading about tens of meters along the shore.
The institute believes that the pumice stones were carried from the undersea volcano by ocean currents to the Philippines, and it is conducting an analysis.
The scientists are warning ships near the area where a large amount of the pumice is floating that the stones can cause damage to the hulls and engines of vessels.
A Japanese researcher has suggested it is highly likely that the pumice stones found on the Philippines' Batan Island came from the Japanese undersea volcano.
Miyama Toru at the Japan Agency for Marine-Earth Science and Technology released a simulation on October 28 that analyzes the movements of the pumice stones.
The simulation suggested that the pumice would reach waters in the northern Philippines around November 20.
Miyama says there is a vortex-like current that travels from waters around Okinawa Prefecture, southwestern Japan, passes east of Taiwan and goes down south toward the Philippines. He says the pumice was likely carried by this current.
He says more pumice stones may reach the Philippines as stones remain in waters around Okinawa.
Miyama also noted there is a possibility that the pumice stones which are floating around the Philippines may drift to the Kyushu region in southwestern Japan in about a month, if they are carried by a current heading toward Japan.