A catastrophe without warning

予期せぬ大災害に備えて

    They are a deadly reminder of how vulnerable humanity is to the destructive forces of nature.

    The world's fourth-largest outbreak of tsunamis in a century has left more than 140,000 dead and millions homeless in countries facing the Indian Ocean, including Sri Lanka, Indonesia, India, Malaysia and Thailand.

    Japan, which is no stranger to tsunami disasters, should provide long-term financial and technical assistance, not just emergency relief.

    At the same time, the nation should step up its efforts to prepare for tsunamis spawned by earthquakes that are predicted to occur off the Pacific coast of central and western Japan.

    There are always lessons and warnings to be drawn from a natural catastrophe.

    One flag raised in the latest tragedy is that there is no full-scale tsunami warning system in the Indian Ocean.

    Another is that coastal towns and villages in the region are almost defenseless against tidal waves in general. In particular, popular resort spots, such as Phuket, Thailand, have no tide embankments along their coastlines.

    In the Pacific Ocean, a tsunami warning center was created in Hawaii following the 1960 Chilean earthquake. Warnings are issued on the basis of seismic waves recorded in Pacific Rim countries, which maintain an extensive observation network.

    By contrast, countries facing the Indian Ocean are ill-prepared for tsunamis. They probably have observation facilities, but none appears to have any working network for transmitting tsunami information to residents, such as disaster hot lines. Nor do they appear to have adequate programs, including ready-to-use guidelines for evacuation, to enhance public awareness of tsunamis.

    A tsunami travels very fast. The waves generated by the Chilean quake reached Japanese shores in 24 hours, leaving 142 people dead or missing. Simple arithmetic shows that the tsunami raced a distance of about 17,000 km at 700 kph -- about the same speed as a jetliner.

    The latest tsunami, unleashed by a 9.0-magnitude quake that occurred off Aceh province on the Indonesian island of Sumatra, is estimated to have reached Sri Lanka in about two hours.

    The lesson is obvious: If residents and visitors had been properly warned, much of the tragedy would have been prevented.

    Japan should do everything it can to help build a tsunami warning system in the Indian Ocean, one that extends from southern Asia all the way to eastern Africa. For now, though, efforts should be focused on emergency assistance, especially medical supplies and sanitation aid to prevent the spread of infectious diseases.

    This is the time to examine our efforts to cope with future tsunamis.

    According to the government's Central Disaster Prevention Council, big earthquakes are likely to occur off the Pacific coast of central and western Japan (Tokai, Tonankai and Nankai regions). Such quakes, it says, will generate powerful tsunamis because, like the one Dec. 26, they will originate from tectonic movements in the seabed plates.

    The maximum death toll in a tsunami from a Tokai earthquake is estimated at 2,200. The number is expected to reach 8,600 if quakes hit the Tonankai and Nankai regions at the same time. To minimize damage, the government is promoting a program to make buildings more quake-resistant.

    The first step in anti-tsunami efforts is to check and, if necessary, reinforce embankments. Beyond that, it is necessary to prepare "tsunami hazard maps" showing in detail how far the waves would advance beyond shorelines. Based on these maps, specific evacuation plans should be drawn up.

    It is especially important to maintain an effective information system. The government plans to install wireless hot lines in all cities, towns and villages in fiscal 2005.

    The national average for prefecturewide coverage by a disaster-prevention radio network was 68 percent, according to a March 2004 survey by the Fire and Disaster Management Agency. In the 23 prefectures likely to be hit by Tokai and Tonankai quakes, coverage ranged from 100 percent to 39 percent. In 10 prefectures it was below the national average.

    The sobering thought is that there are limits to physical measures, such as building embankments, against tsunamis. A tsunami cannot be stopped in its tracks.

    Perhaps the best way to minimize casualties would be to evacuate early. A government study shows that the death toll from an early morning Tokai quake would drop from a maximum of 2,200 to 700 if people were quickly evacuated.

The Japan Times Weekly
Jan. 8, 2005
(C) All rights reserved

      過去一世紀で4番目の規模とされる津波災害で、スリランカ、インドネシア、インド、マレーシア、タイなどのインド洋沿岸各国で、14万人以上が死亡、数百万人が家を失った。

      過去にたびたび津波被害を受けている日本は、被災国に緊急援助だけでなく、長期的財政、技術援助を供与すべきである。同時に、中部日本、西日本の太平洋岸沖に起きると予想される大地震による津波に備えて防災体制を確立すべきである。

      インド洋沿岸諸国では本格的な津波警報システムがない。沿岸地域は津波に対してほとんど無防備であり、タイのプーケット島などの観光地には防潮堤もない。

      太平洋沿岸諸国では、1960年のチリ大地震後、ハワイの津波警報センターを中心とする警報システムが設置された。

      チリ大地震に伴う津波は24時間で日本に到達し、142人が死亡または行方不明となった。津波の速度は時速700キロだった。

      スマトラ島沖のマグニチュード9.0の地震 による今回の津波は、スリランカに到達するまで2時間がかかっている。警報が発令されていれば、人的被害の大部分は防止されたはずだ。

      日本は、南アジアから東アフリカにいたるインド洋沿岸諸国が津波警報システムを確立することに協力すべきである。また、緊急対策としては、感染症予防のための医薬品や、衛生設備供与に注力すべきだ。

      中央防災会議によると、東海地震で引き起こされる津波では最高2200人の死者が予想される。東南海、南海地震が同時に起きれば死者は8600人になるという。

      津波対策は、まず防潮堤の強化、津波災害予測地図の作成である。また、強力な情報システムの維持が肝要である。

      しかし、防潮堤強化などの対策には限界がある。津波は発生してから止めることはできない。

      死傷者を最小限に抑えるには、早期避難が最善だ。政府の調査によれば、早朝に東海地震が起きた場合、迅速な避難で死者は2200人から700人に減少可能だという。