Counts of occurrence per depth in 青森県津軽北部

 Counts of occurrence per depth in 青森県津軽北部 (Northern Tsugaru, Aomori Pref.）is shown as below graph,

The count sum of top 3 (10km/1km/20km) is occupied 88% of all counts. 10km count is the top as the most active one now. 1km's count is the 2nd. But, the activity is stopping currently. And the 3rd, 20km is active still. But, the slope is low‐gradient. So,there may be no dynamic change  for the time being. 

 

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

• 10km (yellow)…The count is the 1st. The largest one of 10km is only M4.8 both in 1932 and in 1988. The longest silent term is between 1940-1958. After being caught by 20km curve, the count began to increase faster. It seems both 1968 Tokachi-oki Earthquake of M7.9 and 1973 Nemuro Peninsula Off-shore Earthquake M7.4 may affect the increases both of 10km/20km even though the epicenter is outside of this area. After the faster increase, the other M4.8 was occurred in 1988, and the count curve was overtaken by 20km. After each the overtaking, the 20km/10km silent terms became longer. By the rapid increase of 20km since 1995, the count of 10km was caught with by 20km almost. By the rapid approach of 20km, 10km's count started the rapid increase again until recently.         
• 1km (red)…The count is the 2nd. The count was the 1st until being overtaken by 10km in 2007. The longest silent term is between 1983 and 2020. The largest of 1km is only M4.9. The recent one was in 2022. 
• 20km(orange)… After being overtaken by 10km curve in 1997, The count is the 3rd. Because of becoming longer the silent terms, it seems to be difficult to catch up with 1km for the time being. The largest one of 20km is only M4.6 in 1970.
• 110km(gray)…The count is the 4th. After 1973 Nemuro Peninsula Off-shore Earthquake M7.4, the curve was overtaken by 10km/20km/30km. The largest one of 110km is only M4.3 in 2017.　 
• 160km…The count is the 5th.But, the count is only 4 times (So, the curve graph is omitted). Even though the few count, M5.5 in 1934 is the greatest one of all depths as same as M5.5 of 30km in 1947.  
• 30km(yellow green)…The count is the 6th, and the count is only 3 times. Even though the few count, M5.5 in 1947 is the greatest one of all depths as same as M5.5 of 160km in 1934.
• others…omitted.