Counts of occurrence per depth in 浦河沖

Counts of occurrence per depth in 浦河沖 (Urakawa offshore region) is shown as below graph, 

M7.1 of 40km is the greatest one of all depths, and was occurred the double junction of 40km/30km in 1982. The M7.1 induced not only the rapid increases of 40km / 30km / 20km, but also the sequential 2nd/1st longest silent terms of 1km. In result, 60km/70km/50km curves have overtaken 1km.     

• 60km(blue)…This count is the 1st. 60km/70km have been overtaking and being overtaken. After overtaking 1km, both of 60km/70km almost overlapped. The largest magnitude of 60km is M6.7 in 1970. 
• 70km(purple)…This count is the 2nd. The largest magnitude of 70km is M6.9 in 1932.   
• 50km(light blue)…This count is the 3rd. After M7.1 of 40km in 1982, the curve rose up around 2004. The largest magnitude of 50km is M6.8 in 1968.
• 1km(red)…This count is the 4th. There was the 2nd longest silent term between 1982-1995. Continuously, the 1st longest one was occurred between 1995-2011. After them, the silent term is becoming longer. The largest magnitude of 1km is M6.8 in 1944.  
• 40km(green)…This count is the 5th. M7.1 was occurred at the double junction of 40km/30km curves in 1982. The M7.1 is the greatest one of all depths. 
• 30km(yellow green)…This count is the 6th. The 30km curve follows the 40km with the similar pattern.The largest magnitude of 30km is M6.8 in 1931.
• 10km(yellow)…This count is the 7th. 10km/90km have been overtaking and being overtaken. The rapid increase was occurred after M5.1 of 10km in 2011. By the aftershocks of M5.1, the longest silent term of 1km since 1995 was interrupted, and the curve overtook 20km/80km curves. The largest magnitude of 10km is M6.0 in 1937.  
• 20km(orange)…This count is the 8th. The curve followed 40km/30km. As same as them, there were 2 major rapid increases as the aftershocks both of M6.8 in 1968 of 50km and of M7.1 of 40km in 1982.  The largest magnitude of 20km is M5.7 in 1942. 
• Others…omitted.