Counts of occurrence per depth in 埼玉県秩父地方 [updated]

Counts of occurrence per depth  in 埼玉県秩父地方（Chichibu region,Saitama Pref.）  is shown as below graph, 

Even the 1st count of 1km, the last occurrence was in 1973. 40km-80km's count is only 1 time. Each of 140km/130km's count rank is the 4th/5th. The greatest one of all depths is only M5.2 of 20km/140km.   

• 1km (red)…The count is the 1st. There was the rapid increase by aftershocks of M6.9 of 埼玉県北部(North Saitama Pref.) in 1931 (The epicenteer of M6.9 was outside of this area). But, the longest silent term has been extending since 1973. The largest one of 1km is M4.3 in 1973.
• 20km(orange) …The count is the 2nd. As same as 1km curve, there was the rapid increase in 1931 by the M6.9. There was also the rapid increase by M5.1 of 20km in 1988. After the M5.1, there was the longest silent term between 1991-2007. The largest one of 20km is M5.2 in 1927. The M5.2 is the greatest one of all depths in this area as same as 140km. The last occurrence was in 2013 (It is the 3rd longest silent term of 20km at this moment). 
• 10km(yellow)…The count is the 3rd. As same as 1km/20km curves, there was the rapid increase in 1931 by the M6.9. After it, 10km curve's slope became gentle until 2006. Since 2006, the slope becomes steeper. The largest one of 10km is M4.8 in 1963.   
• 140km(gray)…The count is the 4th. The count of 140km is only 11 times (7%). The largest one of 140km is M5.2 in 1920. The M5.2 is the greatest one of all depths in this area as same as 20km.
• 130km(gray)…The count is the 5th. The count of 130km is only 9 times. The largest one of 1km is M4.2 in 2022.
• 30km(yellow green) …The count is the 6th. The count of 30km is only 7 times.  The last occurrence was in 1970 (It is the longest silent term of 30km). The largest one of 30km is M3.7 in 1970.
• others…omitted.