Fatalities caused by tsunami generated from a massive quake off Japan's north and northeastern Pacific coast could be reduced by 80 percent if people evacuate quickly, a government task force on disaster management said Tuesday.
The report followed the prediction last year by the Central Disaster Management Council that up to 199,000 people in seven prefectures, including Hokkaido and Iwate, could be killed if a magnitude 9-level quake strikes along the Japan and Chishima trenches.
The task force also called for measures to address issues unique to regions that see extreme cold, such as ways to address evacuation hold-ups due to snow and how to avoid the impact of injuries being exacerbated by extended exposure to low temperatures.
It also studied the possibility of implementing a system in which an evacuation is called for when a possible foreshock of a massive quake is felt, but decided that it would be more appropriate to simply alert residents of an impending threat.
The Japan Trench stretches off Hokkaido to east of the Boso Peninsula near Tokyo, while the Chishima Trench lies off the country's main northern island of Hokkaido to the Chishima Islands, also known as the Kuril Islands.
The Japanese government, which has been undertaking a review of disaster management processes following the 2011 earthquake and tsunami that devastated northeastern Japan, will update its basic plan based on the latest proposal.
To shorten evacuation times, the report called for evacuation routes to be established with roofs and walls to avoid snow and ice accumulation on roads that could slow people's movement.
It also proposed the construction of facilities like evacuation towers with heating and winter clothing available to prevent evacuees from developing hypothermia.
For low-lying areas without easy access to higher ground, it is necessary to consider the best way to evacuate people by car or to relocate residences to higher ground, the report said, while pointing out the importance of education and training to raise awareness of the need to evacuate in an emergency situation.
It also called for the seismic resistance of structures to be increased based on the council's assumption that a maximum of 220,000 buildings could be destroyed by a megaquake and tsunami that could reach nearly 30 meters in height.
Although a system has been introduced to issue an evacuation call in advance of a massive quake around the Nankai Trough, which stretches from western to central Japan, the report said a similar measure is not scientifically appropriate, given the opaque circumstances around the two trenches.
The report, meanwhile, proposed a system to urge residents to stockpile water and food and confirm evacuation sites in preparation for a larger quake if an earthquake of magnitude 7 or greater occurs in or around the assumed epicenter.
As for responses after a disaster, the report called for support plans taking into account the time required for rescue and transport due to snow and icy roads and the need to create medical supply stockpiles.