Massive chunk of volcano slides toward ocean
CBC News Online 28 Feb 2002 18:15:02
STANFORD, CALIF. - A "silent earthquake" in Hawaii caused a 190-square-kilometre
slab of the Kilauea Volcano to slip nearly 9 centimetres into the sea.
A GPS device measures "silent earthquakes" in Hawaii
And no one noticed.
No one, that is, except American researchers using global positioning system (GPS) devices
to measure the slow earth movements.
Geophysicists with the U.S. Geological Survey and Stanford University recorded the silent
earthquake on Kilauea's southern flank in November 2000.
The earthquake measured 5.7 on the Richter scale, but moved so slowly the ground didn't
shake.
A mass of earth 19 by 10 kilometres in area, and eight kilometers thick, slid down the
volcano about nine centimetres over a 36-hour period.
The researchers said a tropical storm that dumped a metre of rain on the Big Island of
Hawaii may have triggered the slide.
The authors of the study, which appears in Thursday's issue of the journal Nature, said
their work could be used to model how a much faster massive land slide could occur.
In an article accompanying the study, geophysicist Steven N. Ward of the University of
California at Santa Cruz said a land mass that size suddenly collapsing into the ocean
would cause a massive tsunami that would threaten coastal areas in California, Chile and
Australia.
A tsunami, or seismic sea wave, can travel up to 800 km/h on the open ocean and can build
up to 20 metres high in shallow water.
But the sudden collapse of a volcano such as this occurs only about once every 10,000
years, Ward said.
The last such collapse in Hawaii occurred roughly 200,000 years ago.
END
OF REPORT
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