## (6) Tsunami measures for railways

The Ministry is examining the status of evacuation and guidance of railway passengers at the time of tsunami occurrence after the earthquake and considering methods to obtain information on tsunami and other warnings issued if means of communications are disrupted, evacuate passengers quickly if trains stop in sections likely to be submerged by tsunami, and evacuate passengers at night. Thus, it will speed up evacuation and guidance at the time of tsunami occurrence and ensure the safety of railway passengers.

## (7) Tsunami measures for government office facilities

Since their facilities are supposed to serve as centers of disaster and emergency response activities or temporary evacuation sites, contributing to the rescue of human life, government offices will take tsunami measures in a comprehensive and effective way in addition to the seismic retrofitting they have done in the past. Specifically, in order to prevent equipment and facilities from flood damage and avoid the loss of important documents, they will install important rooms and equipment at high locations, provide outdoor staircases, and build rooftop evacuation spaces.

## (Response to long-period earthquake ground motions)

Long-period earthquake ground motions refer to seismic vibrations that involve earthquake waves with long frequencies and are characterized by a very long succession of slow quakes. They are estimated to greatly affect super high-rise and similar buildings. When the Great East Japan Earthquake occurred, large vibrations were observed at high-rise buildings in greater Tokyo, Osaka, and other large cities due to long-period earthquake ground motion. It is feared that if a huge earthquake occurs along the Nankai Trough as expected to do so in the near future, super high-rise and similar buildings in Tokyo, Nagoya, Osaka, and other large cities would experience large vibrations. For this reason, the Ministry is currently considering a review of methods to approve under the Building Standard Law measures taken by super high-rise and similar buildings exceeding 60 m in height to cope with long-period earthquake ground motions while watching the results of studies by the Cabinet Office and the Ministry of Education, Culture, Sports, Science and Technology of possible huge earthquakes along the Nankai Trough. It is also considering how information should be provided effectively to prompt initial actions immediately after earthquakes such as early identification of damage to humans and property caused by long-period earthquake ground motion, thus aiming to start providing information on long-period earthquake ground motion that has been observed.

## (Improvements on tsunami warnings)

The Meteorological Agency issued its first tsunami warning three minutes after the occurrence of the March 11 earthquake, but it was pointed out that the Agency underestimated the height of the first waves of tsunami and that this, together with other factors, might have delayed the evacuation of residents, resulting in greater damage. Based on the lessons learned from this experience, the Agency asked academics and experts to examine how to issue appropriate tsunami warnings in order to improve them. It reorganized its policy to improve tsunami warnings so that they would help residents to evacuate more properly and decided to implement a new system of tsunami warnings as soon as possible.

Chart. 58 Standards for Classification of Tsunami Warnings by Wave Height

Classification of tsunami watches and warnings	Warning issuance standards and classification of expected tsunami heights	Expected tsunami height
Issuing warnings using numerical values	Issuing warnings using qualitative expressions
Massive tsunami warning	10 m or higher	Over 10 m	Massive
5-10 m	10 m
3-5 m	5 m
Tsunami warning	1-3 m	3 m	High
Tsunami watch	0.2-1.0 m	1 m	None $ ^{*} $

$ ^{*} $ This is not indicated in the information provided. Source: Meteorological Agency