- In 1995, the world was appalled by the
scenes from Kobe. Last week it was the turn of Zhangjiakou in China. Yesterday,
Japanese scientists predicted an even bigger disaster could be brewing
close to the biggest city in the world. Richard Lloyd Parryreports from
Tokyo on the latest earthquake predictions.
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- Exactly three years after the devastating
Kobe earthquake, which killed 6,300 people, Tokyo appears to be heading
towards an even greater disaster, according to a group of Japanese scientists
who presented their findings yesterday.
-
- Their conclusions are based upon a study
of thousands of smaller tremors, many of them detectable only to the most
sensitive seismological instruments, which have been occurring with increasing
frequency in the Tokai area, south-west of Tokyo. Accordingto the government-backed
National Research Institute for Earth Science and Disaster Prevention (NIED)
these may be a precursor of a new Tokai earthquake, which last struck 143
years ago.
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- "It's pretty alarming," said
Dr Yoshimitsu Okada, director of NIED' s Earthquake Research Centre. "There
are several stages until the Tokai earthquake actually takes place - we
think of it like climbing a staircase. Twenty years ago we decided that
it was dangerous in the long term. Now we have the impression that we've
climbed up a step from long-term alarm to medium-term alarm."
-
- Perched on the convergence point of three
tectonic plates on the so- called Ring of Fire, the Japanese islands have
active volcanoes, hot springs and geysers, and thousands of earthquakes
every year, most of them no more than transitory shudders. But every few
decades comes a huge quake which destroys whole cities and kills large
numbers of people.
-
- In 1923, 140,000 people died in the Great
Kanto Earthquake which had a magnitude of 7.9 on the Richter scale, with
an epicentre under the sea off Tokyo and Yokohama. The Kobe disaster, also
a submarine quake, measured 7.2.
-
- The Tokai area is some 50 miles south-west
of the capital, but the earthquakes which occur there have historically
been even more powerful - the last Tokai earthquake occurred in December
1854, with a magnitude of 8.4. It is this fault which the scientists fear
may become active again.
-
- In the mid-19th century, Tokyo was still
a feudal city of low-rise wooden buildings; today it has absorbed satellite
cities to form a megalopolis of 30 million people, with skyscrapers, overhead
expressways and millions of tonnes of fuel oil andpoisonous chemicals stored
in tanks around Tokyo Bay.
-
- Despite thousands of measuring devices
all over Japan, it is impossible for seismologists to predict earthquakes
as meteorologists predict the weather. "But we can say that the Tokai
earthquake will be much bigger, and the space affected much larger,than
in Kobe," says the director-general of NIED, Dr Tsuneo Katayama.
-
- Historical records show that previous
Tokai quakes have been preceded by unusual seismic events. One of these
is an increase in the frequency of moderate earthquakes,with a Richter
magnitude of 4 or greater, which cause little damage in themselves. As
the graph shows, there were 14 of these in the Tokai area in the 16 years
up to 1996. In the last 18 months, however, there have been no fewer than
seven such quakes. Other recent observations indicate the rate at which
the earth' s crust is sinking has slowed during the 1990s, another precursory
sign.
-
- Modern buildings in Tokyo are required
by law to be "earthquake proof" , but the many older buildings
have never been tested by a real disaster. Casualty numbers are impossible
to predict precisely, but an American projection in 1996, based on a repeatof
the 1923 Kanto tremor, painted a worst case picture of 60,000 dead and
"staggering" economic losses. "It is impossible to say exactly
what will happen," says Dr Okada, "but one thing is certain:
sometime in the future the stairway we're climbing will come to an end."
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- _______________________
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- Quake-Prone Japan On Edge For Big One
By Jon Herskovitz
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- TOKYO, May 4 (Reuters) - The tidal wave
scare that briefly disrupted one of Japan's most popular holidays on Monday
was just business as usual for a nation that always lives under threat
of the earth -- and sea -- moving.
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- Japan's Meteorological Agency estimates
nearly 10 percent of the energy released worldwide by earthquakes each
year is concentrated in and around the string of islands that make up the
nation of japan.
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- In Monday's scare, a 7.7 Richter Scale
earthquake 20 kilometers under the sea off Japan's southernmost Okinawa
islands triggered tidal waves that briefly forced authorities to evacuate
people from coastal areas.
-
- There were no casualties or damage from
the earthquake or tidal waves which barely reached 10 centimeters high,
rather than the two meters that had been feared.
-
- Japan is unusually prone to earthquakes
because it is located at the meeting point of two key tectonic plates,
massive slabs that make up the earth's crust.
-
- Here, geologists say, the Philippine
Sea plate is trying to force its way under the Eurasian plate. According
to the widely accepted "elastic rebound hypothesis," the Philippine
Sea plate is pulling down the lip of the Eurasian, like someone bending
a plastic ruler by pulling it down over the edge of a table.
-
- People in Japan know all too well that
when it goes too far it will spring back, causing a massive earthquake.
Major cities such as Tokyo and most recently Kobe have been flattened this
century in quakes that have killed tens of thousands.
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- Japan is literally criss-crosssed with
fault zones, rips in the Earth's surface caused by quake activity. The
Fossa Magna fault runs roughly north to south through most of the country
while another fault zone roughly runs east to west through the main islands
of Honshu and Kyushu.
-
- Although the entire nation is vulnerable
to quakes, the possibility of a quake that could wipe out the heavily populated
Tokyo area causes the most anxiety.
-
- The area between Tokyo and Osaka, called
the Tokai region, is a hot zone of seismic activity because it is the spot
where the Philippine Sea plate is butting heads with the Eurasian plate.
If the big one occurs here, the Meteorological Agency predicts that Shizuoka,
a city of 3.7 million people 150 km (94 miles) west of Tokyo, will be worst
hit. It will suffer a "very disastrous" quake according to the
Japan's Meteorological Agency.
-
- The most recent estimate by Shizuoka
authorities is that a quake will destroy 69,000 houses and "half destroy"
another 121,000. That is before any outbreak of fire. The shock will be
"very strong" in Tokyo although not comparable to the 1923 disaster,
a 7.9 Richter scale tremor that killed about 140,000 people. A mega-quake
beneath the capital, while long feared, is less likely in the short term,
scientists say.
-
- Authorities have been on edge since April
20 of this year when a series of thousands of tremors, most not felt without
seismic equipment, have rattled the area.
-
- Japan is also vulnerable to tsunami,
a large sea wave that originates from a quake. The largest tsunami to strike
the country this century was the 1933 Sanriku tsunami, which killed 3,008
people in northeastern Japan. It sent a sea surge 14 meters high washing
over coastlines.
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