Photo/Illutration Those residing in areas where tsunami flooding is expected are urged to evacuate for a week after a Megathrust Earthquake Alert is issued. (Asahi Shimbun file photo)

At least 520,000 people nationwide will be asked to evacuate for a week after a Megathrust Earthquake Alert is issued for a potential devastating Nankai Trough megaquake, the Cabinet Office announced on Aug. 20. 

The government’s first survey revealed the number to be evacuated under a Nankai Trough Earthquake Extra Information bulletin.

One of three levels of alert will be issued under the bulletin when the possibility of a Nankai Trough megaquake is imminent.

The Megathrust Earthquake Alert is the highest level alert, which has never been issued.

According to Cabinet Office guidelines, when a Megathrust Earthquake Alert is sent out, residents who may not have enough time to evacuate from a tsunami are urged to evacuate for a week to outside of expected tsunami flooding areas.

The Cabinet Office conducted a survey from June to August covering 707 municipalities located in Tokyo and other 28 prefectures that are designated for ramping up disaster mitigation measures against a Nankai Trough megaquake.

One hundred and thirty of the 707 municipalities have already designated areas necessary for advance evacuation. These 130 municipalities are located in Tokyo and 15 other prefectures.

ASAHI SHIMBUN REPORT TRIGGERED SURVEY

Some of these 130 municipalities have already calculated the number of residents needing advance evacuation.

The total number of people from these municipalities is at least 520,000, with more than half being elderly or people with disabilities who require evacuation assistance.

The number exceeded the 470,000 people evacuated during the 2011 Great East Japan Earthquake and tsunami and subsequent Fukushima No. 1 nuclear power plant accident.

Although the Cabinet Office has been seeking municipalities to designate areas where advance evacuation is needed, it hasn’t tallied the entire number of people who will need to evacuate.

In March this year, The Asahi Shimbun reported that more than 670,000 people live in areas necessary for advance evacuation when a Megathrust Earthquake Alert is issued, based on its original survey of 139 municipalities nationwide.

In response to the report, Manabu Sakai, the disaster management minister, told reporters in a news conference that the government would “thoroughly collect information from municipalities.”

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