Report: Sea gypsies' knowledge saves village

[greenage]

<font color="red">Why does the water recede? </font>

Report: Sea gypsies' knowledge saves village

Report: Sea gypsies' knowledge saves village

Newspaper says Thai fishermen warned of tidal wave

Saturday, January 1, 2005 Posted: 1:20 PM EST (1820 GMT)


BANGKOK, Thailand (AP) -- Knowledge of the ocean and its currents passed down from generation to generation of a group of Thai fishermen known as the Morgan sea gypsies saved an entire village from the Asian tsunami, a newspaper said Saturday.

By the time killer waves crashed over southern Thailand last Sunday the entire 181 population of their fishing village had fled to a temple in the mountains of South Surin Island, English language Thai daily The Nation reported.

"The elders told us that if the water recedes fast it will reappear in the same quantity in which it disappeared," 65-year-old village chief Sarmao Kathalay told the paper.

So while in some places along the southern coast, Thais headed to the beach when the sea drained out of beaches -- the first sign of the impending tsunami -- to pick up fish left flapping on the sand, the gypsies headed for the hills.

Few people in Thailand have a closer relationship with the sea than the Morgan sea gypsies, who spend each monsoon season on their boats plying the waters of the Andaman Sea from India to Indonesia and back to Thailand.

Between April and December, they live in shelters on the shore surviving by catching shrimp and spear fishing. At boat launching festivals each May, they ask the sea for forgiveness.

[wacki]

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fish left flapping on the sand,

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If I ever see this, I will know to run. Good post. I don't have an answer to your questions though.

I wonder how much warning this gives.

[LondonBroil]

"The disappearing beach phenomenon is simple enough to explain. A tsunami wave can travel thousands of miles across an ocean without losing power (one in 1960 crossed the Pacific after an earthquake in Chile and killed 200 people in Japan, more than 10,000 miles away).

When it hits shallow water off a coast it slows right down and builds in height, creating a vacuum that sucks the water off the very beaches it is heading towards."

Times Article

[dogsballs]

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Why does the water recede?

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Well, you know waves have peaks and troughs. And this is a really big wave. Well, this is just the trough ahead of the wave.

edit: the wave only gets big when it reaches the shallow coastal waters. In the open ocean, the wave is hardly noticeable but the power is still there, it's just distributed throughout the water column.

[greenage]

Here is a someone diffeent take on it:

Why is water pulled out of bays and beach fronts as a tsunami approaches? --R. D., Folsom, PA
Heave a rock into a calm lake. Kersplash! Waves emanate in widening circles from the disturbance, eventually hitting the shore. When they reach land, what happens first? Does a wave crest fall upon the land causing lake water to wash up the beach or does the water pull away? It depends on which part of the wave reaches land first: the crest or the trough.

The wave pattern changes upon reaching shallow waters near the shore. The shape of the land--both near-shore floor and coastal contours--reflects and refracts the waves. See Figure 2. As a result of this jumbling, a crest of a local tsunami may occasionally reach land before the trough.

"On the average, however," says Geist, "the trough reaches land first." Then the waters rush out and expose the shallow seafloor. Next the crest deluges the land.

That's why approaching local tsunami waters recede: the trough reaches land first.

Just the opposite happens for distant tsunamis. Occasionally a trough arrives first; then the waters recede first. Otherwise, the crest floods the shore without a warning.

Tsunami!