June 15, 2005

The ten-storey Mexican wave
By Paul Simons and Alan Hamilton

A new record has been set for the largest swell, American oceanographers report
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WHEN seafarers described them in tones of awe, sceptical landlubbers dismissed them as fantasy. Now scientists believe that they have evidence of the largest wave yet recorded.

It happened on September 16 last year when Hurricane Ivan stormed across the Gulf of Mexico and tore into the coast of Alabama, accompanied by 130mph winds and storm surges 8ft high.

While still out at sea, oceanographers report, the hurricane also produced a series of giant waves, one of which stood 91ft (27m) from crest to trough, the height of a ten-storey building and a new world record for a wave recorded by instruments.

But science, like old salts’ tales, is fallible. The seabed instruments that measured the surge were turned off at the moment the winds reached their peak, and scientists from the Naval Research Laboratory at Stennis Space Centre, Mississippi, have had to employ a computer model to predict that, while they were not looking, at the height of the storm the wave reached 131ft.

By comparison, the tsunami wave that swept across the Indian Ocean last December stood about 30ft high as it hit shorelines, although in some parts of Indonesia it was reported to have reached 65ft.

The greatest wave of all is not yet upon us. Scientists predict that if a future volcanic eruption sends a large part of the island of La Palma in the Canaries into the sea, it could cause a wall of water 2,950ft high. Reassuringly, they do not expect the event this century.

The Alabama wave last year comfortably exceeded the previous record for a wave, of 86ft, measured by the ocean weather ship Weather Reporter in the Atlantic on December 30, 1972. Giant waves are difficult to record because measuring buoys floating on the surface of the sea are usually wrecked by the intense storms.

Luckily, the eye of Hurricane Ivan passed over an array of 14 water pressure sensors spread over 38 miles of seafloor 100 miles off the Alabama coast. They are intended to measure the rise and fall of tides but also capture the height of waves. Their results are used for tracking the spread of algal blooms, jellyfish or oil spills from wells in the Gulf of Mexico.

They missed the height of the Hurricane Ivan waves because their work requires them to operate only every few hours.

But they did record that the sea currents generated by the hurricane broke another world record: the maximum current on the seafloor was 2.25 metres per second, compared with the Gulf Stream, which reaches top speeds of about 1.5 metres per second.

“We didn’t expect to measure hurricane waves,” William Teague, of the oceanographic team, said. “We were amazed at the strength of the currents and the size of the waves. It has changed our whole thinking of what could happen out at sea and what structures, like oil rigs, could get wiped out.”

Seven oil rigs were sunk and another 24 badly damaged in the storm. But the worst damage was to submarine pipelines, ruptured by submarine landslides. The hurricane caused the deaths of 116 people across the Caribbean, and insurance claims totalled $28 billion, making Ivan one of the costliest natural disasters in history.

HIGH WATER

Previous highest recorded was 86ft (26.2m) recorded in Atlantic on December 30, 1972

In 1933 the US Navy ship Ramapo was hit by a wave estimated at 112ft in the North Pacific

Waves up to 100ft high are thought to have sunk more than 200 supertankers and container ships during the past two decades. It was such a wave that took star role in Sebastian Junger’s The Perfect Storm

On a crossing to New York the QE2 was hit by a huge wave in the North Atlantic estimated 95ft high from a hurricane on September 11, 1995. She survived after taking the wave directly over her bow. Her captain, Ronald Warwick, described it as “like going into the White Cliffs of Dover”

The tallest underwater wave was measured as a mammoth 558ft on March 28, 2001

HURRICANE IVAN

Hurricane Ivan blasted through much of the Caribbean as a Category 5 storm - the most powerful level of hurricane.

After destroying most of Grand Cayman, it moved into the Gulf of Mexico. The warm waters of the Gulf re-energised the hurricane’s ferocious winds. With virtually wide open sea, the hurricane had a free run to build up the sea into a frenzy. As Ivan approached the Gulf coast of the US, it had piled up the sea into monstrous waves.

Were they struck by a wave of inconsistency? They have feet of waves, miles of seabed, miles per hour of wind and meters per second of ocean current.

And how do you measure the height of an "underwater wave?" Usually wave height is an abnormality in the height of the air-water interface vs. where it is supposed to be.

It would appear that the story was taken from a variety of sources, some American no doubt, but the journalist was too lazy (or incompetent) to convert the measures to a consistent set of units.

The example only re-inforces the mess things are in with half metric countries like US and UK.

The majority of people in any English-speaking country should be able to understand all the units of measurement in that article just fine.

I disagree. How many people can visualise a 558ft wave? In my opinion that would be far better expressed in metres (or yards) It means nothing to me until I divide it by 3.

Largest Mexican wave

The world’s longest Mexican wave consisted of 5,805 participants and occurred on Aberavon beach, Neath Port Talbot, West Glamorgan, UK, on April 14, 2002, in support of the British Heart Foundation.

http://www.guinnessworldrecords.com/content_pages/record.asp?recordid=55100

<<<The world’s longest Mexican wave consisted of 5,805 participants and occurred on Aberavon beach, Neath Port Talbot, West Glamorgan, UK, on April 14, 2002, in support of the British Heart Foundation.>>>

I assume the record refers to the length of the line of people rather than the number of people, because 5,805 people is not very many for a mexican wave - which began at football stadiums with 60,000+ people taking part.

<<
I disagree. How many people can visualise a 558ft wave? In my opinion that would be far better expressed in metres (or yards) It means nothing to me until I divide it by 3.
>>

Heights are never expressed in yards. If you can visualise a 5-foot person, you can visualise a 500-foot wave.

<<<I disagree. How many people can visualise a 558ft wave?>>>

I can easily. I guesstimate 100ft and mpy by 5.

Or use a human reference - a small woman is 5ft. I's use a multiple of that.
I couldn't use yards as a I couldn't imagine walking up into the air

re: "How many people can visualise a 558ft wave?"

REPLY: England's highest cliffs are 630-odd feet high - near Robin Hood's Bay, North Yorkshire. So a 558-foot wave must be just below that in height

<<<REPLY: England's highest cliffs are 630-odd feet high - near Robin Hood's Bay, North Yorkshire. So a 558-foot wave must be just below that in height>>>

I remember going to visit them on a school trip about 15 years ago. Funnily enough no height in feet was ever mentioned by anyone.

Andy, yuo can go on some new trips now - see this programme organised for walks in the area:

---------------------------------------------------------------------------------------------------------------

Day 1 Distance in miles Ascent

Arrival day. - -

Day 2 Distance in miles Ascent

Easier Walk: The Esk Valley - Grosmont to Whitby
6˝ 625 feet

Medium Walk: The Esk Valley - Glaisdale to Whitby
9 850 feet

Harder Walk: The Esk Valley - Lealholm to Whitby
12 1125 feet

Day 3 Distance in miles Ascent

Easier Walk: Across Moorland to return by Rail
4˝ No ascent

Medium Walk: Through the Hole of Horcum to Levisham And Pickering
9 600 feet

Harder Walk: Circular Walk Through Dovedale, Bridestones, Malo Cross and Levisham Moor
12˝ 1125 feet

Day 4 Distance in miles Ascent

Easier Walk: Beast Cliff, Ravenscar and Robin Hood's Bay
8 750 feet

Medium Walk: The Cleveland Way, Hayburn Wyke to Ravenscar and Robin Hood's Bay
8 1025 feet

Harder Walk: The Cleveland Way - Cloughton Wyke, Ravenscar Hutton-Le-Hole
10 1150 feet

Day 5 Distance in miles Ascent

There are no organised walks today to allow you time to explore the area independently or just relax in the House and grounds. - -

Day 6 Distance in miles Ascent

Easier Walk; Abbey, Lastingham and
Hutton-Le-Hole
6˝ 525 feet

Medium Walk: A Ridge, A Rigg and a Hole
9 700 feet

Harder Walk: Rosedale's Railway, Lastingham and Hutton-Le-Hole
12 1075 feet

Day 7 Distance in miles Ascent

Easier Walk: Spectacular Views from the top of the Moors
6˝ 675 feet

Medium Walk: Spectacular Scenery, Ancient Tracks and Jenny Bradley
9 1000 feet

Harder Walk: Wainstones, Cold Moor, Chop Gate To Ingleby Greenhow
12 1800 feet

Day 8 Distance in miles Ascent

Departure day.

From the National Trust website:

"The Cleveland Way footpath runs close to the wall of cliffs, above rocky coves and fishing villages, linking the National Trust's coastal properties. Walkers can enjoy spectacular views, and the cliff tops also provide stunning stop-off points for picnics. Boulby Head, north of Staithes, is Eastern England's highest sea cliff, 650 ft high".

<<I remember going to visit them on a school trip about 15 years ago. Funnily enough no height in feet was ever mentioned by anyone.>>

You can remember the finer points like whether feet, metres or neither were mentioned 15 years ago?

Please tell me our common 'unhealthy' interest hasn't lasted that long!

<<<You can remember the finer points like whether feet, metres or neither were mentioned 15 years ago?>>>

I remember clearly that we only used metric at school and I remember roughly how high those cliffs were - about 200m.

<<Please tell me our common 'unhealthy' interest hasn't lasted that long!>>>

I'm pleased to say it hasn't! My first real interest in this issue was when I stumbled across this site a couple of years ago.

I am proud to say though, that I have only ever been on this site while at work!

Unfortunately (as I'm sure you can appreciate) once you start thinking about this issue, you can't stop noticing every time someone mentions a measurement! (..still waiting to hear my first F-word of the summer even after the scorching weekend!)

<<Unfortunately (as I'm sure you can appreciate) once you start thinking about this issue, you can't stop noticing every time someone mentions a measurement! (..still waiting to hear my first F-word of the summer even after the scorching weekend!)>>

I've put that point down to regional variations.

I used to say that my colleagues were mainly fahrenheit. this is true. however I've changed jobs and my colleagues are mainly C's. Both groups comprise the same age group.