南海トラフ地震臨時情報(巨大地震注意) の解除条件：2024年8月15日（木）

気象庁のホームページには「南海トラフ地震に関連する情報の種類と発表条件」が詳細に掲載されているが，解除条件についての記載がない。いったん，今回のように，8月8日に南海トラフ地震臨時情報（巨大地震注意）が発表されると，この南海トラフ地震臨時情報（巨大地震注意）の「呼びかけ」は1週間行われ，南海トラフ地震の想定震源域でのプレート境界の固着状況に特段の変化を示すような地震活動や地殻変動は観測されない場合，この「呼びかけ」を終了するという。

　気象情報（大雨注意報や暴風注意報など）には，発表と解除がセットになっているが，南海トラフ地震臨時情報（巨大地震注意）には発表はあるが，「巨大地震注意」は南海トラフ地震が起きるまで続くことになり，解除されることはない（解除条件が示されていないので，そのように解釈をせざるを得ないのだろうと私は思うのだが）という理解で良いのだろうか。控えめに言っても，今回のケースは，内閣府の巨大地震注意の発信方法はこじつけのような気がするが，内閣府は「呼びかけ」を終了するだけで，国民には引き続き南海トラフ地震への防災を心掛けてほしいという。

　明らかに，これは危機管理情報のシステムに欠陥があると言わざるを得ない。早急に見直しをすべきである。発表条件と解除条件（有無を含めて）を定義して，自治体をはじめ企業・個人などの国民に対して明示をしないと，防災対応の現場や発表により経済的影響を受ける関係者（特に運輸，観光業や宿泊業など）においては混乱を極めるばかりである。

　なお，気象庁のホームページには，以下の免責条項とも言えるような説明の記載がある。
○南海トラフ沿いで異常な現象が観測されず，本情報の発表がないまま，突発的に南海トラフ地震が発生することもあります。
○地震発生の可能性が相対的に高まったと評価した場合でも南海トラフ地震が発生しないこともあります。
○南海トラフ地震の切迫性は高い状態にあり，いつ地震が発生してもおかしくないことに留意が必要です。

　本日8月15日午後5時を持って，南海トラフ地震の想定震源域でのプレート境界の固着状況に特段の変化を示すような地震活動や地殻変動は観測されない場合，南海トラフ地震臨時情報（巨大地震注意）の「呼びかけ」を終了するという。何のための南海トラフ地震臨時情報（巨大地震注意）の「呼びかけ」だったのだろうか。

The conditions for lifting the Nankai Trough Earthquake Emergency Information (Warning for a Major Earthquake):  August 15th(Thursday), 2024

The Japan Meteorological Agency's website provides detailed information on the types of information related to the Nankai Trough Earthquake and the conditions under which they are issued. However, there is no mention of the conditions for lifting such warnings. Once the Nankai Trough Earthquake Emergency Information (Warning for a Major Earthquake) is issued, as it was on August 8th, the "warning" under this Nankai Trough Earthquake Emergency Information (Warning for a Major Earthquake) will continue for one week. If no seismic activity or crustal deformation that indicates significant changes in the plate boundary conditions within the presumed epicentral area of the Nankai Trough Earthquake is observed, the "warning" will be terminated.

In the case of meteorological warnings (such as heavy rain or storm warnings), issuance and cancellation are set as a pair. However, for the Nankai Trough Earthquake Emergency Information (Warning for a Major Earthquake), there is an issuance, but the "Warning for a Major Earthquake" will continue until the Nankai Trough Earthquake occurs, and it will not be canceled (since the conditions for cancellation are not indicated, we have no choice but to interpret it this way, or so I think). Is this understanding correct? To put it mildly, the Cabinet Office's method of issuing the Warning for a Major Earthquake in this case seems rather contrived. The Cabinet Office says they will only end the "warning" but urges the public to continue preparing for a Nankai Trough Earthquake.

Clearly, it must be said that there is a flaw in the crisis management information system. An urgent review is needed. If the issuance and cancellation conditions (including whether there are any) are not clearly defined and communicated to the public, including municipalities, companies, and individuals, it will only cause confusion among those involved in disaster response and those economically affected by the announcement (especially in the transportation, tourism, and hospitality industries).

Furthermore, the Japan Meteorological Agency's website includes the following disclaimer-like explanations:
○ A sudden Nankai Trough Earthquake may occur without this information being issued if no abnormal phenomena are observed along the Nankai Trough.
○ Even if it is evaluated that the possibility of an earthquake has relatively increased, the Nankai Trough Earthquake may not occur.
○ The urgency of the Nankai Trough Earthquake remains high, and it is important to note that an earthquake could occur at any time.

If no seismic activity or crustal deformation that indicates significant changes in the plate boundary conditions within the presumed epicentral area of the Nankai Trough Earthquake is observed by 5:00 PM today, August 15th, the "warning" under the Nankai Trough Earthquake Emergency Information (Warning for a Major Earthquake) will be terminated. What was the purpose of the "warning" under the Nankai Trough Earthquake Emergency Information (Warning for a Major Earthquake) in the first place?