Muroto Typhoon

This refers to two super typhoons that made landfall near Cape Muroto in Kochi Prefecture. The two are the First Muroto Typhoon (which struck in 1934) and the Second Muroto Typhoon (which struck in 1961), but when people simply refer to it as the "Muroto Typhoon," they are generally referring to the First Muroto Typhoon.

[1] First Muroto Typhoon On September 21, 1934 (Showa 9), this typhoon made landfall near Cape Muroto in Kochi Prefecture, bringing violent storms and high tides from Shikoku to the Kinki region. It moved quickly and made landfall at Cape Muroto around 5:00 a.m. on the 21st, passing through the Kinki, Hokuriku, and Tohoku regions before exiting the Sanriku coast at 6:00 p.m. on the same day. At Cape Muroto, where the typhoon takes its name, a record low atmospheric pressure of 911.9 hectopascals was observed. In the Kanto region and other areas, high tides were called "tsunamis" or "wind tsunamis (corresponding to earthquake tsunamis and mountain tsunamis)," but after the Muroto Typhoon, the word "high tide" became widespread and established nationwide. High tides occurred in areas where the center of the typhoon passed, and the most severe was the area around Osaka Bay, where the average sea level exceeded 4 meters. Wind damage was also severe, particularly near the center of the typhoon and to the southeast, with approximately 300 school buildings across the country collapsing, resulting in numerous casualties among teachers and students. Most of the children and staff who were affected were in or near the school buildings on their way to or after school, and parents who came to pick up their children were also caught up in the collapse. There was also a lot of flooding in the northwestern part of the typhoon, particularly in Kochi, Oita, Okayama, and Tottori prefectures. The damage caused by the storm and high tides was the worst in Osaka Prefecture, with the number of dead and missing nationwide reaching 3,036, mainly in Kinki and Shikoku. The following factors are cited as reasons for the extensive damage caused by this typhoon:

(1) It was a strong typhoon of record magnitude.

(2) Storm warnings were not communicated promptly, and even when they were communicated, their meaning was often not understood and they were not used.

(3) Because the cable was cut, observation data from Cape Muroto was not immediately transmitted to Osaka or Tokyo.

The damage caused by this typhoon was a major shock to Japan's meteorological service, which had been in operation for about 60 years since its inception in the early Meiji period, and various reforms were made, including a complete revision of storm warnings. From the following year, 1935, a clear distinction was made between storm warnings (issued when heavy winds and rains were approaching) and weather special reports (corresponding to today's weather advisories), and the terminology was also revised to make it easier to understand. In addition, there was a lot of damage to railways, such as a train overturning on a railway bridge in Seta, Shiga Prefecture, so railway weather reports were fully launched under an agreement between the Ministry of Railways and the Central Meteorological Observatory. However, with the start of World War II, these disaster prevention measures began to fail. It was during the postwar reconstruction process that the various disaster prevention measures that had been developed in the wake of the Muroto Typhoon began to be utilized.

[2] Second Muroto Typhoon Typhoon No. 18, which made landfall near Cape Muroto on September 16, 1961, was a super typhoon comparable to the First Muroto Typhoon, and was called the Second Muroto Typhoon because it followed almost the same path. Although it had weakened a little when it approached Japan, the minimum pressure at Cape Muroto was 930.9 hectopascals and the maximum instantaneous wind speed was 84.5 meters. Due to sufficient weather warnings and appropriate disaster prevention activities, the damage was less than that of the First Muroto Typhoon, even though Osaka Bay experienced a storm surge of almost 4 meters, the second highest after the First Muroto Typhoon. Compared to the First Muroto Typhoon, there were some significant improvements in disaster prevention measures, such as proper communication of information, early evacuation, the effectiveness of seawalls, and the durability of buildings. However, the number of dead and missing people nationwide reached 202, and the Second Muroto Typhoon was also a very large disaster.

[Yo Narumura]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

高知県室戸岬付近に上陸した二つの超大型台風のことをさす。二つとは、第一室戸台風（1934年襲来）と第二室戸台風（1961年襲来）であるが、一般的にただ「室戸台風」とのみよぶ場合は、第一室戸台風のことをいう。

〔1〕第一室戸台風　1934年（昭和9）9月21日、高知県室戸岬付近に上陸して、四国から近畿地方を中心に激しい暴風雨と高潮をもたらした台風。速度が速く21日5時ごろ室戸岬に上陸後、近畿・北陸・東北地方を通って同日18時には三陸沖へ抜けた。名前の由来となった室戸岬では911.9ヘクトパスカルという記録的な最低気圧を観測した。関東地方などでは高潮のことを「津波」「風津波（地震津波や山津波に対応する呼称）」などとよんでいたが、室戸台風以降「高潮」ということばが全国的に広まり定着した。台風の中心が通過した地方では高潮が発生し、とくに大阪湾一帯がもっとも激しく、平均海面を4メートル超えた。台風中心付近と南東側を中心として風の被害も甚だしく、学校校舎が全国で約300校倒壊し多数の教師や生徒の死傷者を出している。被害にあった児童・職員の大部分は、登校途中か登校後で校舎内や近くにおり、児童を迎えに学校を訪れた保護者たちも倒壊に巻き込まれた。また台風の北西側、とくに高知・大分・岡山・鳥取の各県では水害が多かった。これら暴風雨と高潮による被害は大阪府がもっとも大きく、近畿・四国を中心として全国で死者・行方不明者は3036人に至った。この台風の被害が甚大であった原因として以下のことがあげられる。

(1)記録的な規模の強い台風であった。

(2)暴風警報がすばやく伝達されなかった、伝達されてもその意味が理解されず利用されないことが多かった。

(3)有線の切断によって、室戸岬での観測データが、ただちに大阪方面や東京に伝わらなかった。

　この台風による被害は、明治初期の始まりから約60年を経過しようとしていた日本の気象事業にとって大きな衝撃となり、暴風警報の全面的改正など種々の改革が行われた。翌1935年からは、暴風警報（大風雨の襲来時に発表）と気象特報（現在の気象注意報に相当する）を明確に分け、用語も平易にわかりやすく改めた。また、滋賀県瀬田の鉄橋上で列車が転覆するなどの鉄道被害も多かったため、鉄道省と中央気象台との申し合わせによる鉄道気象通報が本格的に始動した。しかし、第二次世界大戦が始まり、これらの防災対策は機能しなくなっていく。室戸台風を契機に生まれた各種の防災対策が活用されるようになったのは、戦後の復興過程においてである。

〔2〕第二室戸台風　1961年（昭和36）9月16日室戸岬付近に上陸した第18号台風は、第一室戸台風に匹敵する超大型台風で、しかもほぼ同じ経路を通ったため第二室戸台風とよばれる。日本に接近したころは少し衰えたとはいえ、室戸岬では最低気圧930.9ヘクトパスカル、最大瞬間風速84.5メートルを観測した。気象警報などが十分に行われ、防災活動が適切であったため、大阪湾ではほぼ4メートルと第一室戸台風に次ぐ高潮があったにもかかわらず、第一室戸台風に比べると、被害状況の数値は減少していた。第一室戸台風襲来時に比べ、適切な情報伝達、早めの避難、防潮堤の効果、建物の耐久性など、防災対策が格段に進歩した成果もあったが、それでも、全国で死者・行方不明者は202人に達しており、第二室戸台風もやはり非常に大きな災害であった。

［饒村　曜］

出典　小学館　日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について　情報 | 凡例