PROPOSED EVALUATION CURVE REPRESENTING THE RELATIONSHIP BETWEEN CHARACTERISTICS OF SEISMIC MOTION AND HUMAN SENSITIVITY BASED ON SUBJECT EXPERIMENTS

Abstract

 From the lessons of the recent great earthquakes, there is a need to design spaces in which people not only remain physically safe, but also free from anxiety. Therefore, the final goal of this study is to propose the method to reduce anxiety in response to the seismic motion. In a previous study, experiments with human subjects were performed to propose evaluation curves for human sensitivity to seismic motion. Ratios of people expressing anxiety and difficulty in taking action were adopted as indexes of sensitivity to each level of vibration, assuming a normal probability distribution function. The relationship between vibration characteristics and human sensitivity can then be determined using evaluation curves based on simple functions. However, since the scope of the subject attributes was limited and number of samples was not large enough in previous study, the relationship between vibration characteristics and human sensitivity may not show a general tendency. Therefore, in this paper, experiments were conducted by expanding the attributes of subjects to increase the number of samples. Following the experiments, the results were analyzed for each subject attribute and the evaluation curves were updated after comparing the experimental results for researcher subjects and non-researcher subjects. Also, additional experiments were conducted to confirm the effect of different duration, directions, and type of motion, and the effect of motion characteristics other than the size on the human sensitivity are analyzed based on the results of these experiments. Then, the applicability of the evaluation curves was confirmed based on with the past earthquake survey results. The findings are as follows.

 1) Comparing the human sensitivity to seismic motion between research engineers and others, who are more likely to feel anxiety and action difficulty especially for short period vibration.

 2) Anxiety and action difficulty are highly correlated with maximum acceleration A, and yet the correlation with maximum velocity V is low. The evaluation curve improved the correspondence with the experimental results by taking into account the wave period of the vibration.

 3) Among the characteristics of vibration other than the size, the sudden change in the direction of predominant shaking had the greatest effect on the human sensitivity. The effect of duration tends to increase with time of vibration with large amplitude, not with the total time of vibration.

 4) From the correspondence with the past earthquake survey results, it was confirmed that the effects of other than the size of vibration were small in the Kumamoto Earthquake, large in the 2011 Off the Pacific Coast of Tohoku Earthquake, and larger in anxiety than in action difficulty.

 5) Human sensitivity to the seismic motion could be evaluated in general for the epicentral earthquakes by using the evaluation curve. However, for the huge subduction earthquakes, it is necessary to consider the effects of other than the size of vibration. For the 2011 Off the Pacific Coast of Tohoku Earthquake, the effects of other than the size of vibration were converted to seismic motion level Δμ or the number of sections n, while the same value doesn’t always apply to other earthquakes. It is necessary to confirm with a new questionnaire survey whether these values can be applied to other earthquakes.