Copyright 2004 The Federal Capital Press of Australia Pty Limited
Canberra Times (Australia)
April 12, 2004 Monday Final Edition
SECTION: A; Pg. 14
LENGTH: 487 words
HEADLINE: Biggest wave recorded went unseen THE READ
BYLINE: Scott Radway
T HE BIGGEST ocean wave recorded yet - a mammoth 170m high - has been documented off the tiny, low-lying Western Pacific nation of Palau by two scientists studying seawater temperatures.
“It was 170m high, but you will never see it,” says Patrick Colin, director of the Coral Reef Research Foundation based in Palau.
The rogue wave struck on March 28, 2001, but there were no washed-out villages or land devastation.
The wave was entirely underwater and its major effect was rapidly changing seawater temperatures.
Colin says the implications of the findings about deep-water internal waves are “altering our thinking about how coral reefs maintain themselves”.
Coral reefs are bustling homes to sea life in the middle of oceanic deserts.
Ocean water in the tropics is clear because it lacks nutrients - the basic building blocks of sea life - but at the same time, coral reefs flourish.
Some scientists have theorised that the reefs somehow recycle what little nutrients are available, while others have proposed that nutrient-rich water from deep sea is carried up to the reefs to aid growth.
Internal waves now appear to be a likely engine for the latter theory, carrying up cold water packed with nutrients on their towering crests to feed shallow reefs.Eric Wolanski, a physical oceanographer from the Australian Institute of Marine Science, who has been working with Colin over the last year to decipher his findings, says large internal waves could explain why places like Palau have such robust reefs. Colin originally set out to record seawater temperature cycles at varying depths around Palau in order to better understand the 1998 global coral bleaching when rises in surface seawater temperature saw more coral die world-wide - and turn stark white - than ever before in a single event.
In the first six months of collecting data across Palau, Colin was struck by the rapid changes in temperature he found at greater depths that could only be caused by large movements of water up and down, or internal waves.
“There is very little known about internal waves in the tropics, so there is a lot of potential for research,” Colin says.
The waves are found at depths where two layers of water of different densities, determined by their temperature, interface.Rather than cause crashing movements or strong currents, the impact is on the temperature as the colder water goes up and down.
In the case of the 170m wave, Wolanski says the temperature altered from 28C down to 8.5C then back to 28C in 90 minutes.
Waves on the Palau reefs normally range from 50m to 100m, with a usual temperature change of up to 10C.
In trying to ascertain what creates the internal waves, Wolanski and Colin say their data has ruled out lunar tides and passing storms.
Instead, they argue that ocean currents are responsible.
“Like a stone in a stream,” Colin says. “The waves emanate from Palau.” - AAP