南海トラフ巨大地震速報

【南海トラフ巨大地震】

死者最大３２万人、全壊は約２３８万棟想定　内閣府

2012.8.29 18:07 （1/2ページ）［防犯・防災］

　東海・東南海・南海地震の震源域が連なる南海トラフ（浅い海溝）の最大級の巨大地震について内閣府は２９日、死者は関東以西の３０都府県で最大３２万３０００人に達するとの被害想定を公表した。マグニチュード（Ｍ）９・１の地震で最大３４メートルの津波が太平洋岸を襲い、震度７の強い揺れなどで最大約２３８万棟が全壊・焼失すると推定。東海地方から九州までの広い範囲で甚大な被害の恐れがあり、国や自治体に防災対策の抜本的な強化を迫るものとなった。

　死者数の最大は東日本大震災（死者・行方不明約１万８７００人）の２０倍近い超巨大災害で、２００４年のスマトラ島沖地震（約２８万人）を上回る世界最大規模。ただ、南海トラフで起きる次の地震を想定したものではなく、発生頻度は極めて低いとした。死者数は幅があり、最小の場合は約３万２０００人になる。

 Recent announcement from the government on Nankai Earthquake risk.
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TOKYO : Japan's government on Wednesday unveiled a worst-case disaster scenario that warned a monster earthquake in the Pacific Ocean could kill over 320,000 people, dwarfing last year's quake-tsunami disaster.

Tokyo's casualty toll estimate was based on a catastrophic scenario in which a powerful undersea quake of about 9.0 magnitude sparked a giant tsunami that swamps Japan's coastline south of Tokyo.

The Cabinet Office's hypothetical disaster would see the quake strike at night-time during the winter with strong winds helping unleash waves that reach 34-metre (110 feet), sweeping many victims away as they slept.

Many of the estimated 323,000 victims would be drowned by the tsunami, crushed under falling objects or in fires sparked by the disaster, it said.

On March 11 last year, a 9.0-magnitude quake struck seismically-active Japan in the early afternoon, triggering tsunami waves that reached 20 metres.

About 19,000 were killed or remain missing while the tsunami slammed into the Fukushima Daiichi nuclear plant, sending reactors into meltdown and sparking the worst atomic crisis in a generation.

"As long as we live in Japan, we cannot deny the possibility of a huge earthquake and tsunami," Masaharu Nakagawa, state minister for disaster management, told reporters on Wednesday.

The report was designed to paint a worst-case scenario and help officials boost their disaster preparedness.

An estimate in 2003 assumed casualties of about 25,000 people, but that scenario envisioned a less powerful 8.4-magnitude quake striking a smaller area.

The deadliest quake in Japanese history struck the central Kanto region in 1923, killing at least 100,000 people.

Summary of predicted risk of Tokyo Earthquake

Summary of Predicted Earthquakes and the Damage

TOKAI  EARTHQUAKE

Massive Earthquake with an epicenter in Nankai Trough (shallow trench) that would trigger Tokai/Tonankai/Nankai Earthquakes (Cabinet Office Review Board)　

The scale of an earthquake that causes Tsunami is M 9.1.  The estimated height of Tsunami in Kuroshio-Machi, Kochi Prefecture is 34 meters.  The areas where Japanese scale of 7 will be experienced are now 20 times more than previous estimation.  These are much more than we have anticipated before.  In Kanto region, the height of Tsunami is 29.7 meters in Nijima Island in Tokyo and 9.2 meters in Kamakura City in Kanagawa Prefecture.  The height of Tsunami expected at Hamaoka Nuclear Power Plant of Chubu Electric Company in Shizuoka, which is now shut down, is 21 meters.  That is much higher than previously predicted and it is now urgently necessary to revise the safety measures. 

The estimated 21 meter-high Tsunami at Hamaoka Nuclear Power Plant which is located within the predicted epicentral area of Tokai Earthquake is more than the standardized emergency safety measures (15 meters) which have been directed to each electric company by the Nuclear and Industrial Safety Agency at Ministry of Economy, Trade and Industry after the Great East Japan Earthquake.  That is higher than the level that is being built currently at the said Nuclear Power Plant (18 meters) and it would flood the Power Plant.  The fundamental review of the safety measures is now most urgently necessary.  If Hamaoka Nuclear Power Plant explodes, the radiation will reach the Greater Tokyo Area in 6 hours.  

Tokai Earthquake has been occurring regularly in 100 to 150 year cycle.  The last one was Ansei Tokai Earthquake in 1854 and it’s been 157 years since.  Tokai Earthquake can occur any time.  Tokai earthquake may trigger the eruption of Mt. Fuji.

Earthquake in Greater Tokyo Area

This has been concluded by the special project research of the Ministry of Education, Culture, Sports, Science and Technology.  The research team has concluded the magnitude 7 inland earthquake can occur any minute.  They have also publicly announced that the scale of Tokyo Bay Northern Area Earthquake which is one of the possible earthquakes of Greater Tokyo Area Inland Earthquake is predicted to be intensity scale of 7, more than the previously anticipated intensity scale 6 upper.  This was due to the recently discovered fact that the boundary of the sinking Philippine Sea Plate and the continental plate was approximately 10 kilometers shallower than previously believed.   The Japanese scale 7 is expected to be experienced in the bay area, and the mouth of Tama River.   The probability of Greater Tokyo Area Inland Earthquake is 70% within the next four years.* (Preliminary calculation by Tokyo Univ. Research Center  11: 24  1/23/12  Sankei  News [Earthquake, Tsunami, Geoscience])  * Later lowered to 50%.  28% in the next 5 years according to the research of Kyoto University.

Greater Tokyo Area Earthquake Damage Prediction　（In case of Tokyo Bay Northern Area Earthquake,announced as of the date of April 18, 2012 by Tokyo City Government）

　□The death toll is predicted to be maximum of 9,700  (11,000 according to the Cabinet Office) people

　□Totally collapsed buildings, Approx. 304,300 　(850,000 due to fire and collapse)

　□Evacuees 3,390,000　(At the peak, a day after the earthquake) *Ten times more than Tohoku

　□Stranded commuters 5,170,000 (6,500,000 according to the Cabinet Office) people

　□People who are locked in the elevators, 9200 elevators and 12,500 people (apartment buildings

    and office buildings)

  □The height of Tsunami at Tokyo Bay Coastal area is expected to be maximum of T.P. 2.61m at

    full tide (Shinagawa Ward)

　　This takes into account ground level subsidence.  (T.P. = average Tokyo Bay water surface levels)

　□Economic Damage：112 Trillion Yen         

                                   (Reported by Tokyo Metro government office on April 18, 2012)

　　　In addition, damage from liquefaction is expected in Tokyo Bay area.  And individual fires may result in firestorms. 

In case of the Greater Tokyo area earthquake, there will be stranded people in high-rise buildings (people stranded in high rise apartments and office buildings), stranded commuters (6,500,000 people), displaced evacuees (there would be shortage of space equivalent to 12 Tokyo Domes)