Essentially the lesson is
simple. We need to identify all volcanoes
and particularly the mature one in order to determine if the natural geometry
presents a directed collapse risk of significance. Certainly the Canaries abound in this type of
risk.
The events themselves may be
millions of years apart, but they surely can be predicted, just as Mt St Helens
could have been predicted had we had even one similar situation. Since then we have been adept at getting out
of the way.
The real risk from oceanic
Volcanoes comes from the mega tsunamis spawned and again their landfalls are
predictable. It is no trick to have this
information for every piece of populated coast, as we have for hurricanes.
That way the knowledge is always
on hand and is actionable. A school will
know that they are possibly exposed to several threats and easily prepare for
it every year as a matter of tradition.
by Staff Writers
Pablo Davila-Harris looks at part of the huge landslide deposit discovered on Tenerife, showing the chaotic and shattered rubble from the collapsed volcano. (The central dark debris-block is about 15 meters in diameter and must weigh many tons). Credit: Pablo Davila-Harris.
Volcanologists from the University
of Leicester have uncovered one of the
world's best-preserved accessible examples of a monstrous landslide that
followed a huge volcanic eruption on the Canarian island of Tenerife
Seven hundred and thirty-three thousand years ago, the southeast slopes
of Tenerife collapsed into the sea, during the
volcanic eruption.
The onshore remains of this landslide have just been discovered amid
the canyons and ravines of Tenerife's desert landscape by volcanologists Pablo
Davila-Harris and Mike Branney of the University of Leicester
The findings have been published in this October's edition of the
international journal Geology. The research was funded by CONACYT, Mexico
Dr Branney said: "It is one of the world's best-preserved
accessible examples of such an awesome phenomenon, because the debris from such
landslides mostly spreads far across the deep ocean floor, inaccessible for
close study.
"The beautifully-displayed Tenerife
rubble includes blocks of rapidly chilled lava, added as the volcano erupted.
Radioactive minerals within them enabled the researchers' colleague, Michael
Storey at Roskilde University ,
Denmark
"Climate change is often invoked as a trigger for ocean-island
landslides, but in this case it seems that a growing dome of hot lava
triggered the landslide by pushing the side of the volcano outwards.
"In the shattered landscape that remained, lakes formed as rivers
were dammed by debris, and the change to the shape of the island altered the
course of explosive volcanic eruptions for hundreds of thousands of years
afterwards."
The researchers state that such phenomena are common but infrequent,
and understanding them is vital, for their effects go far beyond a single ocean
island. Tsunamis generated from such events may travel to devastate coastlines
thousands of miles away.
"Understanding the Earth's more violent events will help us be
prepared, should repeat performances threaten," they state.
Davila Harris, P., Branney, M.J. and Storey, M. 2011. Large
eruption-triggered ocean-island landslide at Tenerife :
Onshore record and long-term effects on hazardous pyroclastic dispersal.
Geology 39, 951-954.
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