The observed sites of microseisms for the past eight years cover a wide area in the Nohbi plain. Then, it is the purpose of this paper to explain the dynamic properties in the Nohbi plain theoretically and practically. Namely, the observational results of microseisms were compared with the analysed results by two dimensional stationary response analysis. Analysis was executed by the boundary element nethod. We can understand the essentials of dynamic properties in the plain by the above mentioned method. That is to say, response distributions, frequency properties and dynamic properties were clearly recognized. A summary of results of investigating many observed data and analyzed data is shown below. 1) Predominant periods are shown in the zoning map form. 2) Predominant period of observed sites on the soil layer deposits which exists on the sloped bedrock corresponds to the soil layer thickness. The other side, predominant period on the soil layer deposits which exists on the flat bedrock depends on each sites. 3) Predominant period is affected by the soil layer thickness, the slope of bedrock, the distance between the around of the plain and the observed sites, the shape of side border of the plain, the wave length and the dispersed wave. 4) We can not recognize the natural period which is distinguished uniformly in the plain. Each sites have the natural dynamic properties. 5) Dynamic properties near the border between the plain and the outcrop of bedrock are rather complicated phenomena.
