Counts of occurrence per depth in 神奈川県

Counts of occurrence per depth MD-T chart in 神奈川県 (Kanagawa Pref.) is shown as below graph,  

The greatest one of this area is M7.9 Great Kanto Earthquake in 1923. One year ago of it, M6.8 of 90km was occurred in 1922. By the M7.9, the count of 1km increased rapidly by far from others. The silent terms of 1km became longer, and 20km curve overtook 1km curve with the steady increase. 10km/30km/40km curves are following behind 20km curve. Other curve's slopes became gentle with longer silent terms after the M7.9 in 1923.

20km (orange)…The count is the 1st. There was the rapid increase by M7.9 of 20km named as Great Kanto Earthquake in 1923. As the increase was less than one of  1km, the count rank was 2nd or 3rd between 1923-1999. 20km curve has been increasing steadily. On the way, there was the rapid increase as a continuing earthquakes (max M5.5) in the eastern side of M't Fuji in 1976. The M7.9 in 1923 is the greatest of all depths.      

1km (red)…The count is the 2nd. There was the rapid increase by the M7.9 in 1923, and the count rank became the 1st. Then, the silent terms became longer and longer. The longest silent term was between 1981-1994. Since 2000 overtaken by 20km curve, the silent terms becomes shorter. Then, there was a continuing earthquakes caused by M9.0 Great East Japan Earthquake in 2011. There was other continuing volcanic earthquakes around Hakone in 2015. It seems it may be caused by the M9.0 in 2011. as caused by M9.0. The increase of 1km had been observed as of 1919 when Japan Meteorological Agency started the earthquake observation. The largest one of 1km is M7.3 in 1924.

10km(yellow)…The count is the 3rd as same as 30km. Since the rapid increase caused by the M7.9 in 1923, 10km curve was following behind 20km curve except between 1931-1955. There was the rapid increase of 10km caused by M7.3 Northern Izu earthquake (Izu is outside of this area) . The largest one of 10km is M5.8 in 1923.

30km(yellow green)…The count is the 3rd as same as 10km. 30km curve was following behind 20km curve with no overtaking. There was the rapid increase of 30km as a continuing earthquakes (max M5.6) in the eastern side of M't Fuji in 1988 as same as ones (max M5.5)  of 20km in 1976. By this increase, 30km curve overtook 10km curve temporary. The largest one of 10km is M5.9 in 1931.

40km(green)…The count is the 5th. 40km curve was following behind 20km curve. But, after being overtaken by 30km around 1950, the silent terms of 40km became longer and longer. The longest silent term is between 1956-1966. The largest one of 40km is M6.5 in 1923. 

50km(green)…The count is the 6th. 40km curve was following behind 20km curve. The increase has stopped since 2009. The largest one of 50km is M4.9 in 1962. 

110km…The count is the 7th. The graph is omitted

90km(brown)…The count is the 8th. In 1992, 90km curve was accelerated by M5.7 of 90km. 90km overtook 60km/70km curves after it. The largest one of 90km is M6.8 in 1922. The M6.8 seems to be one of the sign of M7.9 Great Kanto Earthquake of 20km because of the one year advanced occurrence before the M7.9.

others…omitted.