MOVING MOUNTAIN BRINGS END OF THE WORLD - SOONER OR LATER Key words: landslides, tsunami, Hawaii

An undersea mountain block 1800 cubic kilometres in size, which is creeping across the ocean
floor from Hawaii, could cause a huge ocean tsunami that would devastate Japan and wreck the
world economy. The wave would travel across the Pacific Ocean as fast as a passenger jet, yet
would be barely noticeable until it approached the shoreline. Then it would devastate areas up to
300 metres above sea level, killing people and causing huge amounts of damage to buildings.
"The question is, can we forecast when it will happen? And the answer is, at present, no," said
Dr. Paul Segall, a geophysicist at Stanford University, California at the American Association for
the Advancement of Science conference here. But measurements taken by radar on board
orbiting satellites have shown that on the south flank of the undersea Kilauea volcano, off
Hawaii, there is a huge block 20 kilometres long by 10 km by 9 km, which is moving at 7
centimetres per year, forced along by lava flowing from underneath it. While that might not
sound like much, it creates the possibility of a "megaslump" - as the block crashes from one
position to another, rather than sliding gently. That would cause an undersea earthquake
equivalent inmagnitude to 7 or 8 on the Richter scale - which would prove devastating on land.
Thousands of tonnes of water would be shocked into motion, and would head west across the
Pacific. The tidal wave would take15 hours to arrive in Japan, where the effects would be
dramatic, and it could take years for the country to recover. Fortunately, such events only seem
to happen about once every 100,000 years, said Dr. Segall. But they have clearly occurred
before: coral remains have been found 300 metres up the side of a basalt mountain in Hawaii, a
finding that cannot be explained by the rise of an undersea volcano, but instead by a huge wave
subsuming the island. While the technology exists to monitor the movement of the underwater
block, there is still no way to predict whether the move - if and when it comes - will be sudden,
prompting a "megaslump", or slower, like an underwater landslide. The latter would cause little
damage. "That scenario is more hopeful, but we haven't recorded any event like that happening.
It's an open question." One problem with a massive tsunami might be the public's reaction to
such a spectacular one-off event. In 1960, a tsunami hit Hilo in Hawaii: when the public was
warned about it, many headed down to the beach to see it come in. Sixty people were killed in
the aftermath.

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