Basic problems of a distribution map of the damaged area, caused by an earthquake are the influence of vacant areas of buildings and the strength of extraordinary of buildings in initial distribution maps for each building. We need to remove them to assess the distribution of damaged area by averaging the distribution of each damaged building.
In this study, we discussed the counter method for averaging the distribution. In general, a counter method is a method to make a contour map of separate planes like a bedding plane using a circle window. In this study, a square window is employed as a counter. The method consists of 7 rules for drawing reasonable boundary lines of selected main damaged areas. Because the counter size affects the figure of the boundary line of damaged areas, we must select a suitable counter size for averaging the distribution of damaged buildings. We observed the distribution maps made by various size counter, and compared between the maps and geomorphological maps.
In the case of the distribution map of damaged buildings caused by the 1995 Hyogo-ken Nanbu Earthquake, we could remove the influence of vacant areas and extraordinary buildings by the counter method. Furthermore, averaging a distribution map of damaged areas by the above method clarified our understanding of the relationships between geomorphological and/or geological factors and earthquake hazards.
These results show that the counter method is useful for averaging a distribution map of damaged area.