Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
. Earth Science News .




SHAKE AND BLOW
Tsunami hit Geneva in AD 563: scientists
by Staff Writers
Paris (AFP) Oct 28, 2012


Nearly 1,500 years ago a tsunami triggered by a rockfall swept Lake Geneva, engulfing its shores with a wall of water up to 13 metres (42 feet) high, Swiss scientists reported on Sunday.

The incident suggests Geneva and Lausanne remain vulnerable today, as do other cities on the edge of mountain lakes and high-sided fjords, they said.

"The risk is underestimated because most of the people just do not know that tsunamis can happen in lakes," Katrina Kremer, an Earth scientist at the University of Geneva, told AFP.

In a letter to the journal Nature Geoscience, Kremer's team said they delved into the "Tauredunum Event," an episode that occurred in AD 563.

A contemporary account by a French bishop, Gregory of Tours, described a catastrophe that was as bewildering as it was terrifying.

A giant wave charged down the lake, destroying villages and herds of animals, and then passed over the city walls of Geneva, on the western tip, where it drowned several people.

Was this a "lake tsunami"? Some experts have argued so.

They point to evidence that part of a mountain slipped into the River Rhone about five kilometres (three miles) from where it flows into Lake Geneva at the lake's eastern point.

Keen to find out more, Kremer's team swept the deepest part of lake with high-resolution radar.

They uncovered a huge, oval-shaped pile of sediment, more than 10 kilometres (six miles) long, five km (three miles) wide and five metres (16 feet) thick.

The thickest point was in the southeast, indicating an origin in the "delta" where the River Rhone flows into the 73-km (45-mile)-long lake.

The team then took four cores of the sediment and carbon-dated tiny vegetal remains embedded in it. The estimated age of this debris is between AD 381 and AD 612.

"Since the AD 563 event is the only significant natural event recorded in historical accounts within our calculated age interval, we consider our dating results to be a strong indication that the deposit is linked to the AD 563 rockfall and tsunami," the letter said.

On that fateful day, believes Kremer, the shock of the rockfall caused the nearby delta's built-up slopes to collapse.

Long, narrow and crescent-shaped, Lake Geneva created ideal conditions for funnelling the maelstrom of mud and water into coherent, amplified waves.

"Our numerical simulations with a shallow water model show that delta collapse in the lake generates a large tsunami at various locations along the shore, where a wave of 13 metres (42 feet) is observed after only 15 minutes, and at Geneva where a wave of eight metres (26 feet) arrives 70 minutes after the mass movement is initiated," the researchers wrote.

In the 6th century, a wave of this height would certainly have had the impact on Geneva that Gregory described, and today would completely inundate large parts of the inner city, they warned.

Over the last 10,000 years, several big slips have occurred, and they could happen again as sediment is building up on the delta slopes -- posing a threat to more than a million people living on the lake shores, said the letter.

"Our study highlights that not only cities located on sea coasts and fjords are at risk from destructive tsunamis, but so are densely-populated lake shores," it said.

Tsunamis are usually associated with an earthquake on the sea floor that occurs close to a coast. The quake raises or lowers the sea bed, and the displaced water forms waves.

But research since the 2004 Indian Ocean tsunami suggests that amplified waves can be created in a range of other scenarios, ranging from volcanic eruptions to dam breaks.

.


Related Links
Bringing Order To A World Of Disasters
When the Earth Quakes
A world of storm and tempest






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





SHAKE AND BLOW
Hawaii rattled by tsunami warning after Canada quake
Honolulu (AFP) Oct 28, 2012
A powerful 7.7 magnitude earthquake off Canada's west coast set off a tsunami warning that emptied restaurants, bars and theaters in Hawaii and sent rattled residents fleeing beach areas. But only relatively small waves rolled to shore on the island of Oahu, and the US Tsunami Warning Center later issued an advisory saying the worst was over. No damage was reported either in Hawaii or in ... read more


SHAKE AND BLOW
Improving healthcare response in Haiti

US governors urge residents to heed Sandy warnings

New York desperately seeks evacuations as hurricane hits

Two missing as Sandy sinks tall ship HMS Bounty

SHAKE AND BLOW
Outdoor wear often coated in harmful chemicals: Greenpeace

French Magpie start-up leaches gold from water with modern alchemy

U.S. unveils new supercomputer

Google unveils large tablet, revamped Nexus lineup

SHAKE AND BLOW
Helping North America's marine protected areas adapt to a changing climate

Australia pumps $1.83 bln into food bowl river

Suez reports operating profit fall on delay to Melbourne water plant

Genetic Patterns of Deep-Sea Coral Provide Insights into Evolution of Marine Life

SHAKE AND BLOW
Biologists record increasing amounts of plastic litter in the Arctic deep sea

Opposite Behaviors? Arctic Sea Ice Shrinks, Antarctic Grows

Italian snow levels, glaciers retreating

New understanding of Antarctic's weight-loss

SHAKE AND BLOW
Gaps in border controls are related to alien insect invasions in Europe

Black rice and tea in Italy as China shows its green side

Honduran crocodile farm bets on skins' glam future

Formula unlocks secrets of cauliflower's geometry

SHAKE AND BLOW
Major earthquake off west coast of Canada, tsunami triggered

Italy minister wants quake ruling overturned

Hawaii rattled by tsunami warning after Canada quake

Tsunami hit Geneva in AD 563: scientists

SHAKE AND BLOW
Rwanda ex-army chief's refugee status questioned in S.Africa

Making transport a driver for development in Africa

Guinea-Bissau army arrests alleged coup leader

Eight killed in militia attack at DR Congo wildlife reserve

SHAKE AND BLOW
Grandmas made humans live longer

How fear skews our spatial perception

New Stanford analysis provides fuller picture of human expansion from Africa

New images could crack ancient writings




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement