- A wave higher than Nelson's Column and travelling faster
than a jet aircraft will devastate the eastern seaboard of America and
inundate much of southern Britain, say scientists who have analysed the
effects of a future volcanic eruption in the Canary Islands.
A massive slab of rock twice the volume of the Isle of Man would break
away from the island of La Palma and smash into the Atlantic Ocean to cause
a tsunami - a monster wave - bigger than any recorded, the scientists warned
yesterday.
Most of the wave's energy, equivalent to the combined output of America's
power stations for six months, would travel westwards to the American coast
but enough would be flicked north towards the English Channel to cause
catastrophic coastal damage.
A computer model has been designed to show the way the tsunami will build
after the volcano, called Cumbre Vieja, erupts on La Palma, at the western
end of the Spanish island chain. It describes the almost unimaginable scale
of an event that the scientists say could happen at any time within the
foreseeable future.
"We're looking at an event that could be decades or a century away
- but there will be a degree of warning beforehand," said Simon Day,
of the Benfield Greg Hazard Reseach Centre at Univeristy College London.
Most of the rocky western flank of Cumbre Vieja is unstable enough to be
dislodged in the next big eruption of the volcano, which is active enough
to explode at least once or twice a century. Its last big event was in
1949.
Such a landslide from a future eruption could travel up to 60 kilometres
(37 miles) from La Palma's coast, causing the formation and then collapse
of a dome of water 900 metres (3,000ft) high and tens of kilometres wide.
The bow of this collapsing dome of water would become a giant wave, but
also, as the landslide continued to move underwater, a series of crests
and troughs would soon generate the "wave train" of the tsunami.
With the leading wave in front and crests pushing it on behind, it would
sustain the power for the nine-hour journey to the American east coast.
Tsunami means harbour wave in Japanese and, though the occurrence has nothing
to do with the tides, it is often called a tidal wave in English. Throughout
history they have caused widespread devastation, with Britain last being
affected by one in 1755 when an earthquake in Lisbon caused an unusually
large wave to hit southern ports.
The computer model, compiled in collaboration with Steven Ward of the University
of California, Santa Cruz, predicts that the tsunami will have a height
of 100 metres (330ft) from crest to trough when it crashes into the shores
of nearby north-west Africa. By the time it reached its final destination,
the east coast of Florida and the Caribbean islands, the tsunami would
still be up to 50 metres high.
Low-lying land in Florida would be vulnerable to a sea wave that would
inundate the mainland for several kilometres inland. Everything in its
path would be flattened, the computer model predicted.
Even though the wave would be much smaller when it reached Britain, it
would still breach sea defences because it would be larger than the biggest
storm waves for which they were designed, Dr Day said. "For low-lying
land along the south coast it could penetrate up to a mile," he said.
Although there is little doubt that the landslide on La Palma will happen
after a volcanic eruption, the difficulty is knowing exactly when it will
occur. "Eruptions of Cumbre Vieja occur at intervals of decades to
a century or so and there may be a number of eruptions before its collapse,"
Dr Day said. "Although the year-to-year probability of a collapse
is therefore low, the resulting tsunami would be a major disaster with
indirect effects around the world."
The scientists are calling for better warning instruments to be placed
on La Palma so that an impending eruption can be detected quickly enough
to alert other areas that might be affected by a tsunami.
"Cumbre Vieja needs to be monitored closely for any signs of impending
volcanic activity and for the deformation that would precede collapse.
The collapse will occur during some future eruption after days or weeks
of precursory deformation and earthquakes," Dr Day predicted.
"An effective earthquake monitoring system could provide advanced
warning of a likely collapse and allow early emergency management organisations
a valuable window of time in which to plan and respond," he said.
A history of tsunamis
The Pacific Ocean is prone to earthquake-induced tsunamis caused by the
so-called ring of fire volcanoes that girdle it. Ten lethal big waves have
struck Japan, Hawaii, Alaska, Chile, Nicaragua and New Guinea over the
past 100 years.
One of the most terrifying tsunamis occurred in 1792 when part of the
Unzen volcano in Japan collapsed into the sea, setting up 100m (330ft)
waves that killed 15,000 people in nearby fishing villages.
In 1868, a powerful tsunami killed 10,000 people when it smashed into
the coast of Peru with enough energy to carry an American warship 3km (1.9m)
inland.
When the Indonesian volcano of Krakatoa blew itself apart in 1883, it
generated a wave that killed 36,000 inhabitants of Java and Sumatra.
Just 13 years later, in 1896, Japanese deep-water fishermen returned to
their home ports to find their homes destroyed and 26,000 dead from a tsunami
that must have slipped below the keels of their ships without them noticing.
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- http://news.independent.co.uk/world/africa/story.jsp?dir=69&story=91098&host=3&p
rintable=1 ___
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- Scientists Warn Of Massive Tidal Wave
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- This Is London.com 8-29-1
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- Britain may be hit by a monster wave predicted to devastate
the coasts of Florida and Brazil following a volcanic eruption in the Canary
Islands.
-
- Scientists warn that the UK would probably not escape
the disaster unscathed. A weaker, but still hugely destructive, wave is
likely to hit Britain's Atlantic coastline.
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- Travelling at speeds of up to 500mph, the tsunami would
be an unstoppable force.
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- Its first target was expected to be the West Saharan
coast of Morocco, where the wave would measure an awesome 330ft from crest
to trough.
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- But the built up coastal areas of Florida, Brazil and
the Caribbean were expected to suffer the greatest destruction, according
to a new forecast by Dr Simon Day, of the Benfield Greig Hazard Research
Centre at University College London.
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- Here, the wave would reach heights of 130ft to 164ft
- higher than Nelson's column - and travel four or five miles inland flattening
everything in its path.
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- Previous research by Dr Day predicted that a future eruption
of the Cumbre Vieja volcano was likely to cause the western flank of the
mountain to slide into the sea.
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- The energy released by the collapse would be equal to
the electricity consumption of the entire US in six months.
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- Working with Dr Steven Ward, from the University of California,
Dr Day has now produced a new model which predicts more accurately how
big the tsunami will be and where it will strike.
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- © Associated Newspapers Ltd.
- http://www.thisislondon.com/
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