Counts of occurrence per depth in 網走沖

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

Most earthquakes were occurred between 1km and 30km. In these shallow depths, the largest one is M6.3 in 1956. The M6.3 was occurred at the twin junction of 1km/20km. The greatest one of all depths was occurred in 150km as the single one of the depth.  

 

 1km(red)…The count is the 1st. The largest one of 1km is M6.3 in 1956. It was occurred at the twin junction of 1km/20km. Since 2017 being close to 10km, the count curve's slope has become steep rapidly.

10km(yellow)…The count is the 2nd. After the longest silent term between 1963 - 2007, the count began the rapid increase. It accelerated after overtaking 20km curve. The largest one is M4.7 in 2007.

20km(orange)…The count is the 3rd. After the twin junction of 1km/20km in 1956, there was the longest silent term between 1974-2009. After it, the count curve became steeper. But, the curve was overtaken by 10km in 2013. the largest one is M5.1 in 1974.

150km…There was only M7.0 once in 1924. The M7.0 is the greatest of all depths. 

Others…omitted.