A draft report indicating the measures that should be taken by residents, businesses and other parties if a strong earthquake occurs in the hypocentral area for a massive Nankai Trough earthquake, including beginning evacuations in other parts of the hypocentral area as well, was compiled Tuesday by the working group of the government's Central Disaster Management Council.
The central government will devise more specific guidelines regarding the measures, and call on such entities as local governments and businesses to devise disaster prevention plans for a Nankai Trough quake (see below) based on those guidelines.
The draft report defines three predictive phenomena:
(1) An earthquake of magnitude 8 or higher strikes on the east or west side of the predicted hypocentral region for a Nankai Trough earthquake
(2) An earthquake of magnitude 7 or higher strikes a smaller part of the envisioned predicted region
(3) A fault shifts inside the predicted hypocentral region
The Meteorological Agency launched an emergency information system in November 2017 that urges the public to be vigilant should any of these phenomena occur. However, disaster response measures following the announcement of information had not been decided.
According to the draft report, the first emergency bulletin will go out about five minutes after an abnormal phenomenon is observed, announcing that investigations have begun as to whether the phenomenon will lead to a successive earthquake.
Should it be decided that any of the three phenomena have occurred, a second announcement will be made in as little as two hours.
The report also states that if the first scenario is determined to have occurred, advance evacuation will also be required of the following people on the side where tremors have not occurred: all residents in areas where evacuation definitely could not be completed between the time an earthquake did occur and the arrival of tsunami, and such residents as the elderly and disabled in areas when evacuation might not be completed during that time.
This decision was based on the fact that in the past, an earthquake on one side of the predicted hypocentral area has triggered a quake on the other.
The relevant areas in this case are those where tsunami at least 30 centimeters high are envisioned to arrive within 30 minutes after an earthquake. The government would call for evacuations to begin at about the same time as the second emergency announcement.
Municipal authorities in the areas would subsequently release evacuation information. The evacuation period is set at about a week, and residents would need to secure their own food supplies.
Even after the evacuation period was over, residents would be called on to maintain greater vigilance than usual for about another week, including making voluntary evacuations.
In the second scenario, the report says that historical precedent indicates the possibility of a massive earthquake occurring is not as great as that of the first scenario. It therefore focuses on voluntary evacuations to last about a week.
In the third scenario, evacuation will not be called for and residents will be called on to exercise more caution in the course of daily life.
In principle, businesses would continue operating in the first and second scenarios.
The report will be presented within the year to the state minister for disaster management. After the New Year's holidays, the Cabinet Office, to which the Central Disaster Management Council belongs, will begin creating guidelines for local authorities, businesses and other parties to use when compiling their disaster prevention plans.
-- Massive Nankai Trough earthquake
A massive quake in which the epicenter is located in an offshore area between the coast of Shizuoka Prefecture and the coast of Kyushu, with the dead and missing estimated at a maximum of 323,000 people. There is believed to be a 70 to 80 percent possibility of a magnitude 8 to 9 earthquake in that area within the next 30 years. Direct damage to homes and other property is estimated at 169.5 trillion yen, or 10 times that of the Great East Japan Earthquake.
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