Counts of occurrence per depth in 宗谷東方沖

Counts of occurrence per depth in 宗谷東方沖（East offshore Soya region）is shown as below graph,

In this area, the depths of the epicenters separate into 2 groups of shallow ones (1km to 30km) and deep ones (260km or deeper).  The magnitudes more than M6 are belong with deep groups more than 250km except 1km.   

•  1km(red)…The count is the 1st. 1km accounts for 30% of all epicenters. The largest one of 1km is M6.3 in 1924.
• 340km(gray)…The count is the 2nd. But, it is only half count of 1km.  The largest one is M7.5 in 1950, and it's also the greatest value of all depths.
• 10km(yellow) and 350km(gray)…The count is the 3rd. But, it is less than 1/3 of the count of 1km. The largest one of 10km is M4.5 in 2016, and the largest one of 350km is M6.1 in 1992.
• Others…omitted..