were swept away by huge waves and drowned. Cars were flushed into the
sea. Ships were thrown onto land where they crashed into buildings. And
hundreds of houses were destroyed in a torrent of water. One of the most
striking television images of the quake was that of what looked to be
an entire house floating out to sea, its roof protruding above the water.
Many things contributed to the damage in the quake, which measured 7.8
on the Richter Scale. There was the shaking, the landslides that ruined
roads and buried a hotel, and fires, probably caused by the explosion
of ruptured gas lines. But perhaps the most spectacular phenomenon was
Waves Outran Warning
While Japan, perhaps tbe world's most earthquake-prone country, has learned
how to build structures to withstand earthquakes, it apparently has not
yet been able to fully cope with tsunamis.
"Even wooden houses in Japan are built strong enough to withstand
the shaking of an earthquake," said Nobuo Shuto, a professor of tsunami
engineering at Tohoku University in Sendai.
has a warning system for tsunamis, but on Monday night the waves reached
Okushiri at about the same time as the warning, five minutes after the
earthquake. "Under this kind of situation, maybe there is little
you can do," Professor Shuto said. "The only way to save human
lives is to evacuate immediately, even without a warning."
Waves Up to 35-Feet High
Professor Shuto estimated that the wave that struck Okushiri ranged from
10 to 16 feet high, but noted that he said he had not completed his calculations.
A researcher for the Meterologicval Agency estimated, based on a survey
of the site, that the waves were as high as 35 feet.
Tsunamis are gigantic versions of the ripples produced by a pebble tossed
into a still pond. But in tsunamis, the water is displaced not by a pebble,
but by an earthquake, volcanic eruption or other violent undersea movement.
A huge mass of water can be displaced.
tsunami's speed depends on the depth of the water above the displaced
sea bed. In the case of the tsunami on Monday, where the water was about
6,000 feet deep, the wave travels at 300 miles per hour.
the wave approaches the land and the ocean becomes shallower, the water
in the back of the wave catches up to the water in the front, and the
wave height mounts.
Report Seeing 10 Waves
Depending on the structure of the coastline, a tsunami might strike one
time and recede, or reverberate, hitting the shoreline many times. Professor
Shuto said some witnesses on Okushiri reported seeing as many as 10 waves.
The professor said that while Japan is most known for tsunamis, they occur
elsewhere, and can strike with deadly force thousands of miles from their
source. A huge tsunami occurred off the Aleutian Islands of Alaska on
April 1,1946, and traveled to Hawaii. Hawaiians thought warnings of a
sea disturbance were an April Fool's joke and ignored them, he said, and
159 people were killed.
began constructing defenses against tsunamis after it was hit by what
Professor Shuto said was the strongest tidal wave in its recorded history,
with waves up to 40 feet high. The tsunami, which struck in 1960 started
off the coast of Chile and took 23 hours to cross the Pacific before slamming
into Japan's Pacific Coast.