Counts of occurrence per depth in 網走地方

Counts of occurrence per depth in 網走地方 (Abashiri region) is shown as below graph,

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

• 1km (red)…This count of the earthquakes is the most one. But, the max Magnitude is M5.1 in 1938 (The max of it in this area is M6.5 of 10km in 1967). The increase was slow down after M6.5 (10km in 1967), and there was the longest silent term between 1975/2002. After it, the counts started rapid increasing in Jun/2004. It may be related with M7.1 (釧路沖地震) in the rapid increase of 1km 2004 as the sign of M7.1 even though the epicenter far from 網走地方. The increasing count of 1km is still continuing. There will be the next great earthquake more than M6 because of the accumulation of many earthquakes since M5.1 in 1938.   
  
• 10km (yellow)…The count is the 2nd after the rapid increase of 1km in 2004.  M6.5 in 1967 is the greatest one in this area, and there was the rapid increase of count over the count curve of 10km. But, as no greater one there has been, the count has been changed to 2nd by the rapid increase of 1km in 2004 related with 釧路沖地震. The count is still continuing. But, not so rapid against the one of 1km. So, the count can't follow up the one of 1km.
  
• 20km (orange)…The count is the 3rd after the rapid increase of 1km in 2004 also. There was the quick step up of the count after M6.1 of 30km in 1959, and then there was the rapid increase of the count in 1965. It was about 2 years before M6.5 (10km) in 1967. By this M6.5, the count has one more rapid increase. But, after it, there was the longest silent term of 38 years between 1978/2016. Still, no more occurrence in 20km.　  
  
• 120km-160km(gray)…The minor peak of counts per depth around 120km. And there was M6.1(160km) in 1997. So, there may be increase the counts of them.