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  1. DISASTER RISK MANAGEMENT
  1. LIFELINE DAMAGE REDUCTION

Lifeline Damage and Its Impact

Lifelines such as water, gas, electricity and telephone, which support urban activities and civil life, remained out of service for a long period due to the destruction of the infrastructure and the breakage of the piping and wiring network. While electricity and telephone services were restored after one or two weeks, it took two to three months for the gas and water supply to be restored. This damage affected the situation in many ways. First, it led to secondary disasters, such as fires caused by electricity redistribution. Second, it made it more difficult to control the situation and conduct emergency medical care. Third, it hampered basic civil life including bathing and excretion. And fourth, it comprised a major obstacle to production businesses and sales. As a result, the vulnerability of a highly developed network-society became obvious.

Lifeline damages can be categorized into three areas. These are namely structural damage of lifeline facilities, system damage caused by the interacting structural damage, and damage of social functions caused by the system damage. In other words, structural damage was due to the fact that facilities lacked earthquake-resistance, systematic damage was due to the fact that the system lacked the ability to stand long and restore itself, and social functional damage was due to the fact that the cities lacked self-controllability and dispersibility.

Disaster Mitigation Measures

The question is how to avoid such long-term and wide-range damage. First of all, lifeline facilities should be made earthquake-proof. We have to directly look at the situation where a great number of non-earthquake-proof facilities and piping exist as a result of rapid urbanization. It is essential to make them aseismatic as soon as possible, especially when we are now facing the possibility of the Nankai Earthquake to occur.

Secondly, an energy and information system which can stand long-term and regulate itself should be established. The system should be able to co-exist with primitive systems such as natural water supply, be supplemented with storage systems for oil and propane gas, be free from ill reactions like power cuts leading to the suspension of water supply, and have multiple supply routes.

Thirdly, the function to restore the system should be improved. Under the present situation of the spreading of earthquake-resistance, damage of lifeline cannot be avoided. Thus, it is a must to establish a system to grab the damage situation at an early stage, a program for swift restoration, and a restoration support system should be set up in the wider area.

Fourthly, a self-sustainable lifestyle which enables people to support themselves when their lifeline is temporarily out of service should be given consideration. This idea includes the use of electricity by solar battery, non-potable water such as well water, and fire made by wood and coal.

Constitutional Improvement of Cities

Various constitutional issues lie in the background of the lifeline-damage. Urbanization has been rapid, population has been expanding, the symbiotic system with nature has been destroyed, self-sustainable life-style has disappeared, efficiency has been regarded more important than safety, and the society has been over-depending on machinery and technology. It is essential to tackle these social and fundamental issues for the drastic solution of lifeline problems. People engaged in public interests should be aware of such aspects and address the issues, while citizens are expected to monitor and support them.

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(MUROSAKI Yoshiteru)