Fig. 4
From: Earthquake early warning: what does “seconds before a strong hit” mean?
Comparison of predicted seismic risk and measured intensities: a map of peak ground acceleration (PGA) distribution (shown with contours of gal) estimated for 100 years over the country published by Architectural Institute of Japan (1987). The original map was derived based on the historical seismic activity by Kawasumi (1951), and was reflected in the modified Building Standard Law in 1981. Actually measured PGAs (in red) that exceeded 600 gal at JMA and NIED strong motion stations in the 1990s including the 1995 Kobe earthquake are indicated; b measured intensities for the 1995 Kobe earthquake. PGAs of over 800 gal were recorded by two instruments in Kobe and assigned intensities (IJMA) were 6, whereas the predicted PGA for this area was 200–300 gal as is shown in (a). Note that at the time, the IJMA scale was described with seven levels from 0 to 6, and was modified to 10 levels (0, 1, 2, 3, 4, 5−, 5+, 6−, 6+, 7) based on the instrumental data in 1996 (see Midorikawa et al. 1999)