<HTML><p>From Yahoo News</p>
<p>
Mega-tsunamis have happened with greater frequency than
modern science would like to believe, and no coastline in the
world is safe, says Canadian geologist-geographer Edward
Bryant.
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He said he had found signs of giant waves sweeping over 425
feet high headlands in southeast Australia, roaring down the
U.S. West Coast and carving into the bedrock of the Scottish
coastline north of Edinburgh.
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"I believe St. Andrews golf course is a tsunami deposit,"
Bryant, head of geosciences at Wollongong University south of
Sydney, told Reuters.
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Over the past 2,000 years, tsunamis have officially killed
462,597 people in the Pacific region alone, with the largest
toll recorded in the Japanese islands.
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Of the top recorded events, the Lisbon earthquake (<A href="[
rd.yahoo.com]; - <A href="[
rd.yahoo.com] sites</A>) of 1755
is said to have triggered a 15-meter high wave that destroyed
the port of Lisbon and caused widespread destruction in
southwest Spain, western Morocco and across the Atlantic in the
Caribbean.
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Modern science blames the killer waves on earthquakes (<A href="[
rd.yahoo.com]; - <A href="[
rd.yahoo.com] sites</A>) and
most countries believe they are immune.
<P>
But in his book, "Tsunamis -- The Underrated Hazard,"
Bryant argues that submarine landslides, underwater volcanoes
and even the potentially catastrophic scenario of a meteorite
impact must also be taken into account when evaluating tsunami
risk.
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That means a destructive tsunami moving at 250 meters per
second in deep water, 85 meters per second across continental
shelves and at 10 meters per second at shore could strike an
unprotected coastal metropolis anywhere, killing thousands.
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GEOLOGICAL DABBLER TO CATASTROPHIST
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In 1989, Bryant was dabbling into the coastal evolution of
rock platforms and sand barriers along the New South Wales
coastline of eastern Australia when he noticed something
strange.
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Giant boulders, some the size of boxcars and weighing
almost 100 tons, were jammed 33 meters above sea level into a
crevice at the top of a rock platform sheltered from storm
waves.
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Further field work found gravel dunes on a 130-meter-high
headland and other massive boulders more than 100 meters
inland. Bryant then examined bedrock that had been savagely
eroded and found that headlands carved into inverted
toothbrushes, where a gap had been roughly gouged in the
middle, existed from Cairns in the far northeast to Victoria
state in the south.
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This could not be explained by normal wave action or
storms.
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"But a tsunami could do this," Bryant said.
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"From being a trendy process geomorphologist wrapped in the
ambience of the 1960s, I had descended into the abyss of
catastrophism," Bryant writes in his book.
<P>
Similar toothbrush headlands exist in northeast Scotland
and gravel has been dumped up to 30 km inland in Western
Australia.
<P>
To the scorn of many modern scientists, Bryant says it is
"naive" to base what we know about tsunamis simply on
documented history.
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In North America and Australia, official history only goes
back as far as white colonization. We may be ignoring the
legends of the Indians of North America, the Aborigines of
Australia or the Maoris of New Zealand at our peril, he said.
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ORAL LEGENDS
<P>
"We ignore all oral record and it's probably a significant
oversight," Bryant told Reuters.
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One Aboriginal tale tells how one of the four pillars
holding up the sky collapsed in the east and the sea also fell
in.
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The Maoris of New Zealand have long spoken of a time of
fire that burned the land to a crisp.
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A legend told by the Kwenaitchechat people of the U.S.
Pacific Northwest tells of a great shaking of the earth that
led to the sea receding and then coming back in a great wall.
<P>
Using dating techniques, Bryant argues there is evidence
that eastern Australia was struck by a mega-tsunami around
1500, which would coincide with the Aboriginal tale of a "great
white wave."
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The Aboriginal accounts of fire in the sky mean a comet
crashing into the South Tasman Sea could have been responsible.
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Carbon dating indicates a great fire ravaged New Zealand at
the same time, giving further weight to the theory of a comet.
<P>
And Bryant said Japanese researchers probing past tsunamis
had found evidence of a massive earthquake off Oregon in
January 1700 that would coincide with the Indian tales, and
with a Pacific seismic zone where the Juan de Fuca tectonic
plate grinds under the North American plate in a process called
subduction.
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"We now know the Oregon subduction zone goes every 300
years. 17002002?" he wonders with raised eyebrows.
<P>
Bryant's suspicions of meteor and comet impacts a
relatively short time ago rile many in the scientific community
who believe the chances of Earth colliding with space debris
are tiny.
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But Bryant says computer modeling suggests a meteor would
not have to be a "dinosaur killer" to cause a mega-tsunami. A
chunk 100 meters in diameter moving at 20 meters per second
could theoretically produce a tsunami that is 27 meters high at
source.
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SUBMARINE LANDSLIDES
<P>
Focusing on extreme scenarios such as meteorite impacts may
also underestimate the risk of a mega-tsunami.
<P>
Contentiously, Bryant argues that underwater landslides,
which can involve thousands of cubic km (miles) of material,
may have the power alone to generate the giant waves.
<P>
A 1998 earthquake off northwest Papua New Guinea has been
blamed for a tsunami that killed around 2,000 people near
Aitape.
<P>
But according to conventional scientific wisdom, the 7.1
magnitude was too small to be responsible for the 15-meter wave
that at some points swept 500 meters inland.
<P>
Bryant says a submarine landslide was the likely villain.
<P>
Another landslide-induced tsunami may have been responsible
for shaping the Scottish coastline, including the dunes of St.
Andrews, 7,000 years ago.
<P>
Scientists have found indications of a large submarine
landslide at Storegga off the east coast of Norway that Bryant
says could have sent a wave originally measuring 8-12 meters
roaring into the North Sea and across the Atlantic.
<P>
Worryingly, he says geologists at the University of Sydney
have recently mapped around 170 submarine landslide zones off
Sydney, Australia's largest city with four million inhabitants.
<P>
What's more, he has found signs that tsunamis have struck
the New South Wales coast with alarming regularity every 500
years.
<P>
If you take the risk seriously, it does not take much to
save human life from tsunamis.
<P>
Chile, Japan and Hawaii already have warning systems and
evacuation drills. Seabed sensors can send tsunami warnings via
satellite triggering bells, alarms and telephones within
minutes.
<P>
"The only guarantee or prediction is that they will happen
again, sometime soon, on a coastline near you," Bryant
concludes.
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"Tsunami are very much an underrated, widespread hazard.
Any coast is at risk."
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