* Astronomy

Blobrana · L

RE: Cumbre Vieja

Blobrana · L

Giant wave could threaten US

The wave would sweep up to 20 km inland

Blobrana · L

A collapsing volcano

in the Atlantic could unleash a giant wave of water that would swamp the Caribbean and much of the eastern seaboard of the United States, a scientist has claimed.

Dr Simon Day, of the Benfield Greig Hazard Research Centre at University College London, UK, believes one flank of the Cumbre Vieja volcano on the island of La Palma, in the Canaries archipelago, is unstable and could plunge into the ocean.

Swiss researchers

If I was living in Miami or New York and I heard that the Cumbre Vieja was erupting, I would keep a very close eye on the news

Prof Bill McGuire

who have modelled the landslide say half a trillion tonnes of rock falling into the water all at once would create a wave 650 metres high (2,130 feet) that would spread out and travel across the Atlantic at high speed.

The wall of water would weaken as it crossed the ocean, but would still be 40-50 metres (130-160 feet) high by the time it hit land. The surge would create havoc in North America as much as 20 kilometres (12 miles) inland.

"This event would be so huge that it would affect not only the people on the island but people way over on the other side of the Atlantic Ocean - people who've never heard of La Palma."

Destructive power

His latest work on the subject has been published in the Journal of Volcanology and Geothermal Research.

On the back of this work, the Geological Society of London is to write to the UK science minister, Lord Sainsbury, to make him aware of the dangers posed by so-called mega-tsunami in the Atlantic.

Simplified geology of La Palma. Thick gray dashed line shows the location of a rift zone proposed by Carracedo (1994). Taburiente and Cumbre Nueva are calderas. The landward scarps of these calderas may mark the headwalls of giant landslides.

Society

should take the issue as seriously as the has the threat from asteroid strikes.

Scientists

have known of the destructive power of tsunami - huge tidal waves - for many centuries. As recently as 1998, over 2,000 people were killed by a large wave hitting the coast of Papua New Guinea.

This was caused by an offshore earthquake. But researchers believe far bigger phenomena can be created by giant landslides.

The largest wave in recorded history, witnessed in Alaska in 1958, was caused by the collapse of a towering cliff at Letuya Bay. The resulting wave was higher than any skyscraper on Earth and gouged out soil and trees to a height of 500 metres (1,640) feet) above sea level.

Summit eruptions

Geological studies have found evidence of giant landslides elsewhere in the world such as Hawaii, the Cape Verde Islands and Réunion in the Indian Ocean.

Dr Day has identified dozens of volcanic vents in the Cumbre Vieja volcano that have been formed by successive eruptions over the past 100,000 years.

He thinks water trapped between dykes of impermeable rock could create pressures that eventually lead to the western flank of the mountain falling away during some future eruption.

Hermann Fritz,

Dr Simon Day: This would be a huge event

of the Swiss Federal Institute of Technology, which has equipment to model waves created by landslides, has stated:

"If the Cumbre Vieja were to collapse as one single block, it would lead to a giant mega-tsunami with an initial wave height of 650 metres.

It would have a wavelength of 30 to 40 kilometres (18 to 25 miles) travelling westwards across the Atlantic at speeds up to 720 km/h (450 mph) towards America."

According to marine geologists

Art Gallery

on studying ancient landslides in the Canary Islands ,a tidal wave able to devastate America's east coast, is vastly overstated.
The researchers are taking part in a three-week research cruise aboard Southampton Oceanography Centre's research ship the RRS Charles Darwin say the threat is far lower than previous warnings would suggest.
In typical landslides, chunks of land break off in bits, not in one dramatic plunge, they claim.
This contradicts previous warnings that an Isle of Man-sized chunk of land could fall off the island of La Palma into the sea, causing a mega-tsunami.
to read more

But

researchers caution that such a catastrophe may not occur for many decades.

"There could be five more summit eruptions of the Cumbre Vieja before the western flank collapses,"

Professor Bill McGuire, of the Benfield Greig Hazard Research Centre.

"There could be 10 or there could be 20 - we simply don't know. But put it this way: if I was living in Miami or New York and I heard that the Cumbre Vieja was erupting, I would keep a very close eye on the news."

Ancient Disasters

Radiocarbon dating

Three Storegga Slides Seabed

of sediments taken from the coastline of eastern Scotland show that a giant wave flooded Scotland about 5,800 BC. At the time, Britain was joined to mainland Europe by a land bridge. Scientists believe a landslide on the ocean floor off Storegga, south-west Norway, triggering 10-meter high tsunamis.
"While there is no reason for mass panic, the possibility exists that the Storegga slide will go again, and it would be imprudent to ignore that fact."

Three Storegga Slides Waves

The three Storegga Slides count among the largest recorded landslides. They occurred under water on the edge of Norway's continental shelf (Storegga is Norwegian for "the Great Edge") in the Norwegian Sea, 100 km north west of the Møre coast, where an area the size of Iceland slid, causing a megatsunami in the North Atlantic Ocean.

Three Storegga Slides Map

As part of the activities preparing the Ormen Lange natural gas field, the incident has been thoroughly investigated. One conclusion was that the slide was caused by material built up during the previous ice age, and that a reoccurrence would only be possible after a new ice age.

The recent tsunamis:

Three Hundred
Thousand
people

The Death toll has surpassed
297,000

have been killed across southern Asia in massive sea surges triggered by the strongest quake in the world for 40 years. About 1,000 km of the Andaman thrust , or faultline, broke.
The 9.0 magnitude quake struck 25km under the sea near Aceh in the north Indonesia island of Sumatra, generating a 5 -10 meter wall of water that sped, at speeds of 500kmh, across thousands of kilometres of sea. The quake struck at 7;59AM, (00.59 a.m GMT) 26th December, with the tsunamis reaching as far as Africa.
This disaster came only days after another massive (8.1) quake occurred 400km offshore of the Macquarie Islands Antarctica, on the 24th. In that quake, there were no tsunamis, or large tidal waves, because the quake moved horizontally rather than vertically.
for more videos

5 million people were directly affected.

Seismologists have determined

that the Dec. 26 Sumatra earthquake was three times larger than originally thought, making it the second largest earthquake ever instrumentally recorded
By analyzing seismograms from the earthquake, Seth Stein and Emile Okal, at Northwestern's Weinberg College of Arts and Sciences, calculated that the earthquake's magnitude measured 9.3, not 9.0.
"The initial calculations that it was a 9.0 earthquake did not take into account what we call slow slip, where the fault, delineated by aftershocks, shifted more slowly. The additional energy released by slow slip along the 1,200-kilometer long fault played a key role in generating the devastating tsunami."
The largest earthquake ever recorded, which measured 9.5, occured in Chile on May 22, 1960.

A strong earthquake,


	Indonesia

measured at 8.7 in magnitude, struck northwestern Indonesia at about 1609 GMT (11:09 p.m. local time) on 28th March 2005.
The quake was located about 1,400 kilometres north of Jakarta, off Sumatra, in the Andaman Sea, in "the same general area" as the Dec. 26 earthquake that measured 9.0. Two aftershocks measuring 6.0 (that struck 30 minutes after the initial quake), and one measuring 6.7 struck 2 hours after, on Tuesday. No major tsunami occurred.
Initial reports : 330 people, ( but could rise to 1,000-2,000), were killed on Nias Island and Simeleu Island near the epicentre of the earthquake, after hundreds of buildings collapsed.
75% of the Gunung Sitoli city was destroyed.
Scientist now believe that this latest quake has stressed the faultlines even further, and brought closer another event similar to the Dcember 26 earthquake.

Four hundred years ago

Bristol Channel

on 20th January 1607, 9.00am. A massive wave devastated the counties of the Bristol Channel, UK. It came without warning, sweeping all before it.
The flooding stretched inland as far as the Glastonbury Tor. Two hundred square miles of Somerset, Devon, Glamorganshire and Monmouthshire were inundated, and up to two thousand people died.
Historians have usually attributed the flooding to a storm but new geographical research, by Dr Ted Bryant of the University of Wollongong in Australia has shown that it was more likely to have been a tsunami.
According to contemporary accounts, the flood occurred rapidly in apparently good weather on 20th January 1607 for about nine of the morning, the same being fayrely and brightly spred, many of the inhabitants of these countreys prepared themselves to their affayres when they saw mighty hilles of water tombling over one another in such sort as if the greatest mountains in the world had overwhelmed the lowe villages a description closer to a tsunami than a storm.

Read more

Source

Blobrana · L

Cumbre Vieja (Spanish: Old Summit) is an active volcanic ridge on the volcanic ocean island of Isla de La Palma in the Canary Islands.
This ridge trends in an approximate north-south direction and covers the southern third of the island. It is lined by several volcanic craters.
Read more