Counts of occurrence per depth in 上川・留萌地方

Counts of occurrence per depth in 上川・留萌地方 (Kamikawa,Rumoi region) is shown as below graph,

note : There are not included of all depth to avoid too complicated curves.

• 1km(red)…This count of the earthquakes is the most one. But, the max Magnitude is only M5.6 since 1932 (The max of it in this area is M6.5 of 260km in 1942). So, the max value should become more than M5.6. In 2022, M5.4 of 1km has been occurred as a series of earthquakes including 10km. This may be the sign of the next bigger one.
• 10km(yellow)…The count is the 2nd. Because of the coming closer to 1km curve, the linkage with it may become easier than before. The rapid increase began after the long silent terms of 1922-1955/1955-1986 (1st/2nd longest). There were the preceding sequences of 20km(orange) before them of in 1995/2004. Especially the one of them in 2004 was included with M6.1. Between 2 continuous ones, there was the long silent term of 1997-2002.
  
• 20km(orange)…The count is the 3rd. The remarkable increase began after the longest silent term of (1919)-1968 (Japan Meteorological Agency has no quantitative data before 1919).
• 30km(yellow green) …The count is 4th. But, the increase has stopped since 2016. After it, the longest silent term has become about 9 years. It may be the sign of the next big earthquake or the continuous earthquakes.
• 40km/50km…40km is only once. 50km is no record.
• Ohters…The count of 150km/160km(gray) are 5th. Except M6.1 of 10km, all the greater earthquakes were occurred in far deeper area of 180km/200km/260km. 

Because of keeping the order of depth in the counts as shallower ones more, the status of earthquake occurrence is more stable one especially in shallow area. But, the big earthquakes more than M6 must be occurred in shallow area (1km/10km/etc.) as the order changer of them. Because 1km's huge earthquakes are the one of the final release of the stocked earthquake energy of deeper area.