1990 Volume 63 Issue 1 Pages 108-119
The Tokyo Lowland has suffered from natural disasters several times, because thick soft ground is developed over a broad area and the ground height is low. In addition, land below sea level came into existence during the 1930's due to land subsidence and continued to expand. It now covers about 68 km2.
The Great Kanto Earthquake brought the largest damage ever caused by a natural disaster in Japan. Fires were to blame for the majority of lost lives and destoyed houses in the Tokyo Lowland. As a result, countermeasures for fires have been regarded as most important against an earthquake. The Tokyo Lowland has suffered from three separate types of flood disaster: due to the collapse of river banks, storm surges and inland waters. Also, there is a risk of flood disaster induced by an earthquake.
Two characteristics are remarkable in the Tokyo Metropolitan Government's policy for urban disaster prevention. One is that disaster-proof city planning should be based on security, but works for an emergency should fit in with everyday life. The other is that construction of disaster prevention facilities should be based on the long-term urban development plan. These have been well realized in the several kinds of countermeasures undertaken in and around the Koto District, especially in construction of the Shirahige Higashi Disaster Prevention Base.
By examining relationships among land conditions, landuse, natural disasters and countermeasures on the Tokyo Lowland, it is proven that artificial changes to the natural conditions and landuse done in past become the threshold conditions for improvement works in the future.