WORKING GROUP 8 
NAKANO-OHYA-KANAKUBO 
451 
the Chilean earthquake, reached the Pacific coast of Japan. In this disaster, 
139 people were drowned, 5,015 houses were destroyed, and many ships were 
lost. 
The same procedure as after the Ise-wan Typhoon was followed. The photo 
graphs taken by the Defence Army of Japan and the Asia Aero Survey 
Company, Tokyo, were used for micro-geomorphological analysis and to 
obtain details of the destruction. The 1 : 15,000 photos taken immediately 
after the disaster were particularly useful. In the photo interpretation we could 
analyse: 
a. the movement of the tidal wave over the land; 
b. the area inundated; 
c. areas of erosion and deposition; 
d. damage to houses, bridges and other constructions, and 
e. micro-landforms. 
The field survey included a description of the area itself, the maximum 
depth of inundation, the time at which the water reached its highest level, 
the time when the inundation by each tidal wave started, the velocity of the 
tidal waves, and the magnitude of the disaster. 
A landform classification map of the coasts devastated by the Tsunami was 
compiled, together with one showing the size of the tidal waves and the damage 
caused by them. From these we could formulate the following relationships be 
tween the abnormal tidal waves and landforms. 
1. There are distinct regional differences in the character of the tidal waves. 
These are caused by differences in coastal morphology. 
2. The main routes taken by the tidal waves, their maximum extent, and 
their period of stagnation, are closely related to the coastal landforms. 
3. The penetration inland of the tidal waves varies with the morphological 
details such as the valley plain, wave-cut benches, deltas, sandspits, sand- 
dunes, artificially filled-in areas, the beach, and the dry river bed. 
Application to town planning 
The nature and duration of flooding can thus be forecast from the micro 
relief of the plains. By studying this, we can foretell the type of future floods, 
and the amount of damage which they may cause. Planning of future cities 
and villages along the coasts will be greatly influenced by considerations of 
landform and flooding. 
The results of this survey were thus valuable not only as a study in physical 
geography, but also for reconstruction work and town planning. The same 
ideas have been applied to give the fundamental data for flood prevention in 
the alluvial plain of the Bay of Tokyo, one of the regions most liable to flood. 
The landform classification map for flood prevention in the city of Tokyo and 
its vicinity, has been compiled from aerial photographs and field investigation. 
From these landform maps, the project of flood prevention most suited to 
a particular area can be planned.