Earthquakes - Tokyo
Climbing The
Stairway To Hell
By Richard Lloyd Parry
Independent News

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.
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.
"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."
Quake-Prone Japan On Edge For Big One By Jon Herskovitz
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.
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.
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.
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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