2020 Volume 20 Issue 7 Pages 7_101-7_119
Since the 1995 Southern Hyogo Prefecture Earthquake, the seismic intensity observation system in Japan has developed dramatically. This paper summarizes the transition from the start of seismic intensity observation in Japan to the present. Analysis of seismic intensity data from the JMA seismic catalog showed that as the density of seismic intensity observation points increased, the number of strong motion observations closer to the epicenter increased and the observed maximum seismic intensity increased. In addition, by considering the surface layer amplification and population distribution for each area obtained by dividing the whole country into voronoi regions based on seismic intensity observation points, it was shown that even in the cases of similar magnitude earthquake, the observed maximum seismic intensity increases when it occurs in a densely populated area with the soft ground and the dense observation points. This paper quantitatively shows the changes in the times and regional difference of the maximum seismic intensity observed, and clarifies the characteristics of the seismic intensity station arrangements of the Japan Meteorological Agency, National Research Institute for Earth Science and Disaster Resilience, and local governments.
