Abstract
　The Western Nagano Prefecture earthquake of September l4, l984 with magnitude 6.8 on J.M.A. (Japan Meteorological Agency) scale occurred near Ohtaki village in Kiso Disthct (l37.5゜E, 35.8゜N). The earthquake caused the debris avalanches and the slope failures in a large scale. The damage due to those has been reported by many investigators.
　This paper dea1s with the damage of structures due to ground motion itself. Through the investigation of tombstone overturn and measurements of aftershocks and microtremors, the authors estimated the dynamic characteristics of strong ground motions due to the main shock and studied the correlation between the damage to the structures and those characteristics.
　Findings in this paper can be summarized as follows;
l) The characteristics of the main shock at Ohtaki village are supposed that maximum horizontal acceleration is about 400 gals and predominant frequency is relatively hith.
2) The damage to wooden building seems comparatively light; mainly fall of the roofing tiles and permanent deformation between the ground still and foundation.
3) As for lifeline systems, electric service was recovered on that day, telephone service and water supply service, however, needed 20 days and l6 days, respectively. And yet such emergency as above ground piping was made for water supply service.

*金沢大学工学部
Department of Civil Engineering, Kanazawa Univ.