Hazard maps of Kugahara
Released on 21 March, 2005

Kugahara parts of hazard maps are shown in this corner from the publications of Tokyo Metropolitan Government and Keihin River Office of Ministry of Land, Infrastructure and Transport.

  1. Degree of earthquake risk
  2. Degree of flood risk
1. Degree of earthquake risk
The Tokyo Metropolitan Government assumes the magnitude of quake and damages of the metroplitan areas in the case that an earthquake occurs on the boudary of plates along the upper face of Philippine Sea Plate, which is pointed out by Central Disaster Prevention Committee to be imminent.
The conditions of the earthquake are assumed as follows.
1. Epicenter Direct beneath the ward area, direct beneath Tama area, direct beneath the boundary to Kanagawa Prefecture, and direct beneath the boundary to Saitama Prefecture.
2. Magnitude M7.2
3. Time Around 6:00 p.m. of a winter weekday
4. Climate conditions Clear weather, wind 6m/s (21.6km/h, 13.5mph)
The assumed damages shown below are based on the "direct beneath the ward area", which is assumed most disastrous among the four possible epicenters listed above.
Distribution of earthquake intensity

Kugahara is among the areas of "intensity 6 lower".

Maps of risks

Descriptions

Building collapse risk
Building collapse risk indicates the degree of risks of collapse and leaning of buildings by earthquake. The risk is determined from the conditions of ground and buildings of the area.
The parameters include the number of buildings classified by structure, uses, number of floors and age.
Along with the evaluation of risk of ground by the classification of ground, the possibility of liquefaction is also included into the judgement of the ground. The parameters to evaluate ground include classification of ground, evaluation of risk of liquefaction, and developed land of large scale.
Fire risk
Fire risk indicates the combined degree of risks of fire breakout by earthquake and the risks of fire spread.
Evacuation risk
If fire breaks out by an earthquake, it is important to try initial extinction actions to prevent it to grow into a big fire. It is also important, however, to evacuate in the case of danger of life. The degree of evacuation risk is evaluated by combining the time needed to get to the designated evacuation site and the number of people to evacuate. It rises as the distance to the designated evacuation site increases, impediment factors against evacuation exist along the evacuation route, and as the number of people who evacuate grows.
The parameters include the distance to the designated evacuation site, impediments, traffic jam, blocking of roads by fire spread, velocity of evacuation and evacuation population.
Total risk
The degree of total risk is the sum of the degrees of building collapse risk, fire risk and evacuation risk, and is classified into five ranks.

2. Degree of flood risk
Keihin River Office of Ministry of Land, Infrastructure and Transportation, which administers Tamagawa River, publishes "assumed flood area maps". The maps are based on the simulation of the area and the depth of flood in the case of bank rip of Tamagawa River by heavy rainfall. It is known that Tamagawa River causes flood at the probability of roughly every two hundred years. A well-known flood in recent history is the one in 1910, when the flood water from Tamagawa River reached the Oimachi area.
Map of assumed flood by Tamagawa River for all Tokyo area

Kugahara's map of assumed flood by Tamagawa
Legends

Lower than 0.5m (1.64ft)
0.5m - 1.0m (3.28ft)
1.0m - 2.0m (6.56ft)
2.0m - 5.0m (16.4ft)
Over 5.0m (16.4ft)

All the towns and "Chome" of Kugahara are fortunately out of assumed flood areas, except for the roads along the Nomigawa River, but it can be found that the flood water from Tamagawa River can reach Chidori 1-chome, which lies next to Kugahara in the south.


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