Counts of occurrence per depth in 福井県嶺北地方

Counts of occurrence per depth in 福井県嶺北地方（Reihoku region, Fukui Pref.）is shown as below graph,  

• 1km (red)…The count is the 1st. There were 2 major rapid increases both in 1927 and in 1948. The first one was caused by M7.3 of 20km of Northen Kyoto  (outside of this area).   After the rapid increase of 1km in 1927, the silent terms became longer and longer.  Then, there was the anoher major rapid increase of 1km in 1948 by M7.1  of 1km in 1948.  Then, the silent terms became longer and longer as same as before. After the longest silent term (at that time) of 1km between 1965-1968, the occurrences of 1km was acceleratated temporary by M7.0 of 10km in 1961. The next acceleration was occurred by M5.9 of 10km in 1972 after the longest silent term (at that time) of 1km between 1969-1972. Since these accelerations of 1km, the silent terms became longer and longer. The 1st longest term of 1km is between 1992- 2003. After it, the  silent terms became shorter gradually. The M7.1 of 1km greatest one of all depths.
• 10km(yellow)⋯The count is the 2nd. There was the rapid increase by the M7.1 of 1km in 1948 after the 2nd longest silent term between 1943-1948 (The first one is between 1919-1934). The rapid increased count of 10km became 103 at the next rapid increase by M7.0 in 1961. The count of 10km is similar with the conut  97 of 1km at M7.1.  There was the temporary increase of 10km by the M7.0 of 10km in 1961, and there was the 3rd longest silent term (at that time) of 10km between 1966-1970. Then, M5.9 of 10km was occurred as the 2nd scale magnitude of 10km. The silent terms of 10km became shorter and shorter. In result, the count of 10km is approaching to 1km's one. The largest one of 10km is the M7.0 in 1961.
• 20km(orange)⋯The count is the 3rd. There is the major rapid increase of 20km by the M7.1 of 1km in 1948 after the 2nd longest silent term between 1943-1948 at that time (The first one was between 1919-1931). After the 2nd longest silent between 1963-1972 at that time, there was the temporary acceleration of the occurrences of 20km since 1972 at the count 24. The start count of 20km is similar with the one of the rapid increase of 1km in 1927 as count 21. Then, there was the longest silent term of 20km between 1973-2011. The largest one of 20km is M4.8 in 1957. 
• 30km(yellow green)⋯The count is the 4th. But, the count is only 4 times. The latest occurrence was in 1961, and the longest silent term is extending now. The largest one of 30km is M4.5 in 1961. 
• others⋯There is no occurrence in other depths.