Study of the Relation between the Subsoil Conditions and the Distribution of the Damage Percentage of Wooden Dwelling Houses in the Province of Totomi in the case of the Tonankai Earthquake of December 7th, 1944

Since old times the dependence of earthquake intensity on the subsoil condition has been well-known in this country. In compliance with the national postulation to promote the building of rational and economical earthquake-resistant structures throughout our land of earthquakes, the study of the foundation coefficient for the enhancement of earthquake intensity due to the subsoil condition has been undertaken from various points of view by many scientists and engineers. Most reliable and direct data have been obtained from the observation of the earthquake intensity in actual large earthquakes in the locality. Relative intensity of an earthquake can be inferred from the difference of dynamical effect on the same kind of physical system. As Japan is very densely populated, the dwelling house is one of the most prevalent objects throughout the country, and in addition its mode of construction is almost identical within a certain area. Actually the frequency distribution of the strength of wooden dwelling houses in our country has been proved to be normal in many instances. Therefore, the percentage of houses destoryed to a certain degree in a locality may be deemed to be the best measure of the mean intensity of the earthquake in the locality. If we take, therefore, the area of a locality properly, we can obtain reliable mean intensity for a place of a given subsoil condition