Disaster Prevention Measures for Tokyo… before March, 11 2011

It is obvious that these terrible twins earthquake, tsunami, and nuclear menace will call for a new vision for Japanese cities. As it is too early to draw predications, I would like to go back to a research led by Professor Hidetoshi Ohno of Tokyo University: Tokyo 2050: Fibercity, in particular in one part of his vast research: the Disaster Prevention Measures. In the first decade of the 21st century, Professor Ohno has conceived Tokyo 2050: Fibercity as a vision of the future of Tokyo based on a new balance between natural and built environment in response to Tokyo urban issues — lack of open spaces, green areas, narrow roads, tiny lots, horizontal city, so forth. He has declined four core points: decreasing population, aging society, environmental crisis and earthquake potential. From these four elements he implemented four strategies: Green Fingers, Green Web, Green Partition, and Urban Wrinkle. Let's put Hidetoshi Ohno's Fibercity aside and focus on the Disaster Prevention Measures and Management.
New York Times readers have probably read the article Japan's Strict Building Codes Saved Lives published March, 12 2011. James Glanz and Norimatsu Onishi went back over Japanese building Codes to understand Tokyo's disaster prevention strategy. I invite the readers who have not read this article yet to read it for more information. I will merely post the Disaster Prevention Measures for Tokyo available in the Tokyo 2050: Fibercity issue edited by Hidetoshi Ohno's Tokyo 2050: Fibercity for the Japan Architect Magazine issue #63, Autumn 2006. This Disaster Prevention Measures is crucial in Japanese urban policies, where earthquakes are common. This instrument permits to protect the population, to control constructions in seismic areas. It includes a public education program; It helps determine areas for evacuation measures, risk during fire and risk during building collapse. This list is non exhaustive. The following text is part of the JA issue #63: Tokyo 2050: Fibercity.

Disaster prevention measures by the Tokyo Metropolitan Government are comprised of four plans: an earthquake disaster prevention plan, a disaster preparedness plan, a disaster emergency response plan and a disaster recovery and reconstruction plan.

Vulnerability to People's Evacuation © Bureau of Urban Development Tokyo Metropolitan Government

Investigation of the risk according to district areas is being conducted as the basis of these plans in view of the evaluation of the current preparedness against possible urban disaster in this investigation, the risk of earthquakes in evaluated from three viewpoints for every 5,073 neighborhoods in the Tokyo town planning area. These three viewpoints are as follows: the risk of collapse of a building assessed in terms of strength of ground and building, the risk of fire assessed in terms of potential outbreak and spread of fire, and the evacuation risks assessed in terms of the time that may be required to arrive at the evacuation area, and the number of evacuees who would take shelter.

Vulnerability to Fire © Bureau of Urban Development Tokyo Metropolitan Government

The Tokyo Metropolitan Government (TMG) updates this evaluation every five years.
it is apparent in these assessments that the districts evaluated as risky are concentrated in the area between Ring Road No. 6 and Ring Road no. 7 where there is a density of wooden buildings. Moreover, the plans mentioned above are based on the division of district areas for evacuation.
Evacuation areas are specified for each district and evacuation roads are specified for districts far from evacuation areas. In addition to such preparative measures, such as implementing traffic restrictions to secure emergency transport routes, the construction of emergency supply warehouses and specification of large disaster rescue bases is also underway.

Vulnerability to Building Collapse © Bureau of Urban Development Tokyo Metropolitan Government

These measures are not limited to TMG. These are the same measures that have been applied for the North-East Japan and the entire Japan. With the climate changing, Japan may face increased natural disasters such as earthquake and tsunami. It is not be a surprised that these Disaster Prevention Measures will be improved in response to these increasingly challenge issues (creation of more evacuation spaces, reinforcement of building codes, creation of more green areas, etc.)

Japan Disaster Prevention Measures Plan can be checked on Tokyo Government Disaster Prevention homepage with information available in Japanese and in English.