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Quake researchers warn of Tokyo's 'Big One'

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Published : March 5, 2012 - 17:12

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A year on from one of the biggest earthquakes in recorded history, Japanese scientists are warning anew that Tokyo could soon be hit by a quake that will kill thousands and cause untold damage.

Greater Tokyo, home to 35 million tightly packed people, has seen a three-fold increase in tectonic activity since the magnitude 9.0 undersea quake that unleashed a killer tsunami last March.

Every day, an average of nearly 1.5 quakes are recorded in and around the city, one of the most populated places on earth.

But Tokyoites are so used to being shaken in their beds or at their desks that the majority pass almost without comment.

The city is, without doubt, one of the most earthquake-proofed places in the world. Even the monster quake of March 11 last year that struck just 370 kilometres (230 miles) away caused little structural damage.

Public transport was thrown into temporary disarray, leaving thousands stranded, but no buildings collapsed and there were no large-scale casualties.

The University of Tokyo's Earthquake Research Institute says the city, built at the intersection of four tectonic plates, has a 50 percent chance of suffering a major quake -- anything above a magnitude 7.0 -- in the next four years.

"We must prepare for the earthquake that will happen," says Asahiko Taira, executive director of the government's Japan Agency for Marine-Earth Science and Technology.

A simulation by the agency suggests that if an earthquake with a magnitude of 7.3 occurred in the northern part of Tokyo Bay on a weekday evening, around 6,400 people would die, with 160,000 injured.

Approximately 471,000 homes and buildings would be destroyed, most of them by fires, or because of liquefaction, a process where reclaimed land turns to mush.

Around 96 million tonnes of waste would be instantly generated -- four times the total left behind by the tsunami that hit the northeast coast.

Millions of people would be unable to get home and emergency shelters would be over-run. More than one million households would be without water, gas, electricity and telephones for several days.

Economically, the cost would be a colossal $1.45 trillion -- around a third of Japan's GDP.

The impact of a huge quake on the political, economic and cultural centre would be felt nationwide, causing widespread disruption to life throughout the archipelago and beyond, given Japan's influence in global industry.

Japan -- which experiences a fifth of the largest earthquakes on Earth every year -- lost its capital to the power of nature once before, when the Great Kanto earthquake of 1923 levelled the city.

That 7.9 magnitude quake and the ensuing fires killed an estimated 142,800 people, according to the US Geological Survey, and left an institutional memory of what it means for a country to be effectively decapitated.

The suggestion of a back-up capital has long been considered. Osaka, 550 kilometres (345 miles) further west, is suggested as an appropriate destination.

So far, the vast costs of establishing government-in-duplicate have put off any serious moves by politicians of any stripe, who are already battling a huge mountain of debt and a sluggish economy.

However, scientists caution, something must be done to mitigate the risk.

"It is extremely difficult to predict exactly when an earthquake will strike, but we can understand what might happen and from there we have to develop strategies to minimize the consequences," said Taira.

But some experts fear Japanese seismologists are so consumed with thinking about Tokyo's "Big One" that they have become blinkered to risks elsewhere.

Expert Robert Geller said that in a country with 54 nuclear reactors, the risk of a large quake striking anywhere in the archipelago should not be ignored in favour of concentrating on Tokyo.

"The government's estimate that the risk in (this area) is greater than elsewhere is based on a flawed methodology and is completely meaningless,"

Geller, a professor in the Department of Earth and Planetary Sciences at the University of Tokyo, told AFP.

"The incorrectness of this methodology should be obvious, since the same methodology was used by the government before last March 11 to say that the risk in the Tohoku (tsunami-hit) area was very low." (AFP)

 

<한글 기사>

日학계 "4년내 도쿄에 대지진 가능성"

인구 3천500만명이 밀집한 일본의 수도권 지역에서 4년 내로 규모 7.0 이상의 강진이 발생할 가능성이 50%에 이른다는 연구 결과가 나왔다.

도쿄대 지진연구소는 지난해 3월 동일본 지방에 규모 9.0의 대지진이 발생한 이 후 도쿄를 포함한 수도권 지역의 지각활동이 3배 증가했다면서 5일 이같이 밝혔다.

지구 상에서 가장 인구 밀도가 높은 일본 수도권 지역에는 매일 평균 1.5회의 지진이 발생하고 있다. 그러나 침대와 책상이 흔들리는 수준의 지진에는 익숙해진 수도권 거주자들은 생활에 지장을 받지 않는다.

도쿄는 내진 시설이 탄탄해 동일본 대지진 당시에도 건물이 무너지거나 사상자가 발생하는 일이 없었다.

그러나 과학자들은 수도권에 지진이 발생했을 때 피해를 최소화하기 위해 지금 부터 대책을 마련해야 한다고 촉구하고 있다.

일본 해양연구개발기구(JAMSTEC)는 평일 저녁에 도쿄만 연안에 규모 7.3의 지진 이 발생하면 약 6천400명이 사망하고 16만여명이 부상당한다는 시뮬레이션 결과를 발표했다.

이 과정에서 47만1천여채의 주택과 건물이 파괴되고 수십만 명이 집을 잃고 긴급 대피소를 찾을 것이라고 JAMSTEC은 예측했다. 또 100만 가구 이상에 며칠간 물, 연료, 전기, 통신이 끊기게 된다.

JAMSTEC에 따르면 도쿄에 대지진이 발생하면 지난 3월 동일본 대지진 때 배출된 쓰레기양의 4배인 9천600만t의 쓰레기가 배출된다.

지진으로 인한 경제적 피해는 일본 국내총생산(GDP)의 3분의 1 수준인 1조4천50 0억달러에 이를 전망이다.

타이라 아사히코 JAMSTE의 연구원은 "언제 지진이 발생할지 정확히 예측하는 일 은 극도로 어렵지만 어떤 일이 일어날지는 예측 가능하다"며 "이에 따라 피해를 줄이는 방안을 마련해야 한다"고 말했다.

도쿄가 대지진으로 마비될 가능성에 대비해 오사카를 대체 수도로 육성하자는 제안이 제기됐지만 막대한 비용문제 때문에 현재 정치권의 움직임이 없는 상태다.

과학자들이 도쿄에 찾아올 '한 방'을 지나치게 우려한 나머지 전국 54개의 원자력 발전소 인근에 지진이 발생할 가능성을 간과하고 있다는 의견도 있다.

도쿄대의 로버트 갤러 교수는 도쿄 지진을 예측한 방법이 잘못됐다면서 "지난해 3월11일 동일본 대지진이 발생하기 전에도 정부는 같은 방법으로 지진을 예측했는데, 도호쿠 지방에서 지진이 발생할 가능성이 작다는 결론을 내렸다"고 말했다.