Counts of occurrence per depth in 青森県三八上北地方

Counts of occurrence per depth  in 青森県三八上北地方 (Sanpachi Kamikita region, Aomori Pref.）is shown as below graph, 

The most great count is 1km. But, after the longest silent term, the increase becomes very slow. 10km curve has overtaken 70km-90km curves and following 1km. But, the count of 10km is far from 1km still. There may be no major change  for the time being.

note : Earthquakes with red font have the epicenters outside of this area. 

• 1km (red)…The count is the 1st. The count increased with steep slope until M6.6 of 70km in 1960. Then, there were about 3 years silent terms twice and the largest earthquake of 1km as M4.9 in 1976. Further after that, the longest silent term of 1km was occurred between 1978 and 2013.  
• 10km(yellow)…The count is the 2nd. Before Great East Japan Earthquake M9.0 in 2011, the count increased with gradual slope and the count was under 5th.  After M9.0, the curve's slope became steeper and overtook 70km-90km curves. After the overtaking, the count seems to be accelerated. The largest one of 10km is M5.8 in 1978. 
• 20km(orange)…The count is the 3rd. After the 2nd longest silent term between 1986-1997, there was a rapid increase since 1997. But, then, 10km curve overtook 20km. The largest one of 20km is M4.7 in 1986.　
• 30km&40km…The counts are only one and the magnitudes are unknown.
• 50km(light blue)…The counts are only 2 times. The largest one of 50km is M4.1 in 1939.　
• 60km(blue)…The count is the 10th. The largest one of 60km is M5.2 in 1971. The M5.2 is the last occurrence, and the record of the longest silent term is updating now.
• 70km(purple)…The count is the 5th. Since 1958, the count increase rapidly. But, after M6.6 of 70km in 1960, the silent terms became longer. After M5.7 of 90km, they became further longer. The largest one of all depths is M6.6 in 1960.
• 80km(navy)…The count is the 3rd. The curve was overtaken by 10km in 2024 recently. The largest one of 70km is M4.9 in 1960.
• 90km(brown)…The count is the 4th. After M6.6 of 70km in 1960, the curve caught up with 80km. Then, 90km/80km curves have become entangle. The counts are almost same now. The largest one of 90km is M5.7 in 2015.　 
• others…omitted.