It is useful in planning the safety countermeasures of initial behavior at earthquake that the walking ability at the time shaking by earthquake is studied. In order to investigate the relation between intensity scale of earthquake and walking speed, walking experiments were carried out on the table of the shaking machine. JMA seismic intensity scale was 3∼6 ranges. The walking distance of subjects was 2 m on this hypothesis that man was in a house. Though the number of subjects were the few (male 15, female 15), the followings were chiefly found in this experiment.
(1) The average walking speed of subjects at earthquake motion did not change at a standstill so far as JMA seismic intensity scale 4. However, the walking speed gradually began to decrease from JMA seismic intensity 4. The decrease ratio of the walking speed has increased as JMA seismic intensity becomes stronger than 4.
(2) It was the maximum speed in the vibration factor of the floor that the walking speed at earthquake motion could be showed with one straight line irrespective of the frequency. The walking speed of subjects has decreased in proportion to the maximum speed of the floor.
(3) The average walking speed of male and female were nearly the same speed, but female reached to a walking limit with weaker seismic intensity scale than male. There was a individual difference in the walking speed and limit.