Roof-Tile Damage of Wooden Houses on Improved Hills Caused by the 2001 Geiyo Earthquake and Micro-Tremor Properties of the Ground
the 2001 Geiyo earthquake
This paper presents the relation between roof-tile damage of wooden houses and ground shaking intensity by the 2001 Geiyo earthquake. The roof-tile damage of wooden houses caused by the Geiyo earthquake was surveyed at residential districts in and near the western part of Hiroshima City， Koi-ue， Nishi-Ward， and Ajinadai， Hatsukaichi City. Also questionnaire investigation for housing damage and ground shaking intensity was developed in Kure City and Ajinadai. Furthermore，a micro-tremor measurement technique was employed to investigate ground vibration property. The results are as follows: (1)Extensive damage of roof-tiles occurred on fill ground than cut ground. (2)The questionnaire seismic intensity is high on alluvium ground near hills and on ridges in Kure City，and on fill ground on improved hills in Ajinadai. The threshold intensity above which the roof-tile damage starts to appear can be between 5.5 and 6.0. (3)A ratio of horizontal spectrum to vertical one based on the micro-tremor measurement is found to have clearly different characteristics between fill and cut ground. This ground vibration property corresponds to larger roof-tile damage of wooden houses in fill ground on improved hills.