Counts of occurrence per depth in 岐阜県美濃地方

Counts of occurrence per depth in 岐阜県美濃地方 (Hida region, Gifu Pref.) is shown as below graph,

The 10km/ 1km curves saw accelerated growth following major earthquakes, with the 10km curve overtaking the 1km curve after the M6.8 in 1984. While 20km/40km curves generally followed both 10km/ 1km curves, they experienced a period of being closely intertwined between 1981 and 1989 following an M6.6 event. 

• 10km (yellow)…The count is the 1st. There were 3 major rapid increases of 10km. The 1st rapid increase was between count 39-43 of 10km by M5.5 of 1km in 1948. The 2nd one was between count 131-149 of 10km by M6.6 of 1km in 1969. The 3rd one was between 188-206 of 10km a by M6.8 of 1km in 1984. After the 3rd one,  10km curve overtook 1km curve. Before and after the overtaking,  the increase of 10km count accelerated more. The largest one of 10km is M6.3 of 10km in 1934.
• 1km (red)…The count is the 2nd. There were 3  major rapid increases of 1km count since 1945. The 1st rapid increase was between count 146-151 of 1km by M5.5 of 1km in 1945 by M6.8 of 10km in 愛知県（Aichi Pref.）. The 2nd one was between count 249-270 of 1km in 1961 by M7.0 of 10km in 石川県加賀地方（Ishikawa Pref.). The 3rd one was count between 332-350 of 1km by M6.6 of 1km in 1969. After that, there was the longest silent term between 1986-2004 (count 391-392). 2 years later, M6.8 of 1km occurred in 1984 as the greatest one of all depths. Durinng the longest term of 1km, 1km curve was overtaken by 10km curve. Then, the count increase of 1km became slower. 
• 40km(green)⋯The count is the 3rd. 40km curve is following behind 10km curve. The count of 40km increased step by step gradually. The ranking of the longest silent terms are as follows (chronological order). The 2nd one was between 1920-1925. The 3rd one was between 1946-1950. The 1st one was between 1973-1981(as count 51-52). Then, the slope of 40km curve became steeper. The largest one of 40km is M5.6 in 1925.   
• 20km(orange)⋯The count is the 4th. 20km curve was following behind 40km curve except in 1931/1981-1989. 20km curve overtook 40km curve only once in 1931. Then, 20km curve was delayed from 40km curve again for a long time. After the rapid increase of 20km by M6.6 of 1km in 1969, both 20km/40km curves were closely intertwined temporarily between 1981-1989. In the rapid increase of 20km, the count was between 31-41. The end count 41 of 20km was near to the end count 43 of the 1st major rapid increase of 10km. After the end of 20km,  20km curve became close to 40km curve between 1981-1989. The largest one of 20km is M5.1 in 1966. 
• 50km(light blue)⋯The count is the 5th.  50km curve was following behind both 40km/20km curves. The largest one of 50km is M5.3 in 1975. 
• 30km(yellow green)⋯The count is the 6th. Both 30km/20km curves were closely intertwined until around 1960. Then, there was the longest silent term between 1964-2000. Since 2000, there have been no more occurrences. It means the latest silent term is extending for 25 years. The largest one of 30km is M5.5 in 1939. 
• 60km(blue)⋯The count is 7th. 60km curve is following behind 50km curve. The largest one of 60km is M5.3 in 1975. 
• others⋯ As remarkable ones of others, there were M6.6 of 250km in 1931/M6.0 of 260km in 1954.