TOKYO – An erupting volcanic island that is expanding off Japan could trigger a tsunami if its freshly-formed lava slopes collapse into the sea, scientists said on Tuesday.
The small, but growing, island appeared last year and quickly engulfed the already-existing island of Nishinoshima, around 1,000 kilometres (620 miles) south of Tokyo. It now covers 1.26 square kilometres (0.5 square miles).
The island's craters are currently spewing out 200,000 cubic metres (7 million cubic feet) of lava every day -- enough to fill 80 Olympic swimming pools -- which is accumulating in its east, scientists said.
"If lava continues to mount on the eastern area, part of the island's slopes could collapse and cause a tsunami," warned Fukashi Maeno, assistant professor of the Earthquake Research Institute at the University of Tokyo.
He said a rockfall of 12 million cubic metres of lava would generate a one metre (three feet) tsunami that could travel faster than a bullet train, hitting the island of Chichijima -- 130 kilometres away -- in around 18 minutes, he said.