MD-T chart in 群馬県南部（South Gunma Pref.）
Sunday, August 31, 2025
Sum of Magnitude per 1day in 群馬県南部
Sum of Magnitude per 1day in 群馬県南部（South Gunma Pref.）
Counts of occurrence per depth in 群馬県北部
Counts of occurrence per depth in 群馬県北部（North Gunma Pref.）is shown as below graph,
The counts of 1km-20km is occupied 96%. Both 1km and 10km curves has been overtaking each other since 2000 including the rapid increases as the aftershocks of M9.0 Great East Japan Earthquake. 20km curve stopped after the longest silent term between 2003-2023.
- 1km (red)…The count is the 1st. 1km curve had kept the 1st rank until 2000. There was the longest silent term between 1989-1999. During it, 1km curve was overtaken by 10km curve once. But, the rapid increase of 1km was caused by M5.9 of 1km as the one of the aftershocks of M9.0 Great East Japan Earthquake. As the increase of 1km was more than the one of 10km, 1km curve became the 1st rank. 2 years later, 1km curve increased again by M6.3 before being caught by 10km curve. Both the M5.9 and the M6.3 of 1km were the largest one at that time. The M6.3 is the greatest one of all depths.
- 10km (yellow)…The count is the 2nd. There was the longest silent term between 1919-1933. The 5th one（the 2nd at that time）was between 1937-1941 after 4 years. Furthermore, the 2nd one continued between 1942-1949 after 1 year. After it, the silent term became shorter until 1970. Then, there were the 4th and the 3rd longest silent terms between 1970-1974 / 1974-1981. After them, the curve slope became steeper until 2011. During it, 10km curve overtook 1km as wrote above. In 2011, there was the rapid increase as the ones of aftershocks of the M9.0. But, the increase of 10km was less than 1km. The largest one of 10km is M5.2 in 2018.
- 20km (orange)…The count is the 3rd. 20km curve was following behind 10km curve until 1988. Then, the silent terms became longer. After the longest silent term between 2003-2023, there has been no earthquake. The largest one of 10km is M4.9 in 1975.
- others…The sum of counts among the 1km-20km is occupied 96%. Others are omitted.
Friday, August 29, 2025
Sum of Magnitude per 1day in 群馬県北部
Sum of Magnitude per 1day in 群馬県北部（North Gunma Pref.）
Wednesday, August 27, 2025
Counts of occurrence per depth in 栃木県南部
Counts of occurrence per depth in 栃木県南部（South Tochigi Pref.）is shown as below graph,
Only 1km's count is occupied 50%. Other depth curve's increase are slower. 30km-40km curves has stopped between 1966-1973. 20km has stopped since 2015. The 2nd count is 10km curve. But, the count is only 11% of all. M6.4 of 10km is the greatest one. Just before it, M6.2 of 1km was occurred as the largest one of 1km.
- 1km (red)…The count is the 1st. The count is occupied half of all occurrences in this area. There was the rapid increase before and after related with M7.9 of Great Kanto Earthquake in 1923 (The epicenter was in the western area of Kanagawa Pre.). Furthermore, there was both M6.2 in 1942 and the aftershocks in 1949-1950. After it, the silent terms became longer gradually. The longest silent term is between 1988-1994. Then, it became shorter gradually. The M6.2 in is the largest one of 1km.
- 10km (yellow)…The count is the 2nd. As same as 1km, there was M6.4 just after the M6.2 of 1km in 1949. The time difference was only 7 minutes. As the magnitude of 10km was larger than 1km, the M6.4 of 10km is the main shock. The M6.4 is the largest one of all depths in this area. M5.8 of 10km was also occurred the next day. After around 1994, the curve became steeper.
- 50km(light blue)…The count is the 3rd. 50km curve has been increasing smoothly with no major significant fluctuation. 50km curve was overtaken by 10km curve increased by M9.0 Great East Japan Earthquake in 2011. The largest one of 50km is M5.3 in 1939. The largest one of 50km is M5.3 in 1939.
- 60km(light blue)…The count is the 4th. 60km curve is similar with 50km, and both curves has been overtaking and being overtaken. The largest one of 60km is M5.6 in 1937.
- 70km(purple)…The count is the 5th. 70km curve is following behind both curves of 50km/60km. The largest one of 60km is M5.4 in 2011 as the one of the aftershocks of the M9.0.
- 40km(green)…The count is the 6th. 40km curve increased smoothly until after around 1930. After it, 40km curve increase began less than 50km-70km curves. The silent terms became longer and longer. The occurrence has stopped since 1973. Until now, the longest silent term is continuing still. The largest one of 40km is M5.2 in 1924.
- 80km(navy)…The count is the 7th. The count is occupied only 2% of all earthquakes in this area. The largest one of 80km is M5.9 in 2011 as the one of the aftershocks of the M9.0. The M5.9 of 80km was occurred 2 years later of the longest silent term between 1997-2009.
- 30km(yellow green)…The count is the 8th. 30km curve is similar with 40km curve, and was following 40km curve behind. But, as same as 40km curve, the increase has stopped since 1966. The largest one of 30km is M4.7 in 1923.
- others…The sum of counts among the 1st (1km)-6th(40km) is occupied 90%. Others are omitted.
Sunday, August 24, 2025
Sum of Magnitude per 1day in 栃木県南部
Sum of Magnitude per 1day in 栃木県南部（South Tochigi Pref.）
Area map of 栃木県南部
Area map of 栃木県南部（South Tochigi Pref.）is defined for epicenter's analysis as below,
Counts of occurrence per depth in 栃木県北部
Counts of occurrence per depth in 栃木県北部（North Tochigi Pref.）is shown as below graph,
1km-20km is occupied 93% of all occurrences. 1km curve increase after both M6.2 in 1949/M6.3 in 2013. In this year, the curve become towards upper because of a continuing earthquakes in 福島県会津. As 10km curve also has been increasing since around 1984. On the other hand, 40km curve's silent term since 2013 is continuing to extend as the 2nd longest. These increases might be the sign of some great earthquake near 福島県会津 not too far away.
- 1km (red)…The count is the 1st. There was the rapid increase before and after related with M7.9 of Great Kanto Earthquake in 1923 (The epicenter was in the western area of Kanagawa Pre.). Furthermore, there was M6.2 and the aftershocks in 1949-1950. After it, the silent terms became longer gradually. The longest silent term is between 1988-1994. Then, it became shorter gradually. When the curve went towards upper, M6.3 was occurred in 2013. It seems to be affected by M9.0 Great East Japan Earthquake in 2011. The M6.3 is the largest one of 1km.
- 10km (yellow)…The count is the 2nd. As same as 1km, there was M6.4 on the same day as the M6.2 of 1km. The time difference was only 7 minutes. As the magnitude of 10km was larger than 1km, the M6.4 of 10km is the main shock. The M6.4 is the largest one of all depths in this area. M5.8 of 10km was also occurred the next day. Around 1984, the curve became steeper, and is approaching to 1km still.
- 20km(orange)…The count is the 3rd. After the 3rd longest silent term between 1930-1938, 20km/40km curves were overlapped between 1941-1741 before the M6.2 of 1km. 20km curve jumped up between 1949 -1950. But, there was the silent term between 1950-1953 after it. Then, 30km curve start increasing again following 1km/20km. The increase become slower since around 1973, and the 4th and the 1st longest silent terms were occurred after them. The each term is between 1981-1988 / between 1988-2011. The 4th one seems to be occurred in place of the steeper increase around 1984. On the other hand, the 1st one seems to be one of the signs of the M9.0. After the 1st longest one, no earthquake has been occurred except 1 earthquake in 2013. The 2nd longest silent term is extending the record since 2013.
- others…The sum of counts among the 1km-20km is occupied 93%. Others are omitted.
Thursday, August 21, 2025
Sum of Magnitude per 1day in 栃木県北部
Sum of Magnitude per 1day in 栃木県北部（North Tochigi Pref.）
Area map of 栃木県北部
Area map of 栃木県北部（North Tochigi Pref.）is defined for epicenter's analysis as below,
Wednesday, August 20, 2025
Counts of occurrence per depth in 千葉県南東沖
Counts of occurrence per depth in 千葉県南東沖（Southeast offshore Chiba Pref.）is shown as below graph,
There were rapid increase of the aftershocks of M7.9 of Great Kanto Earthquake in 1923. Especially, 1km curve jumped up higher than others and has being kept the rank as the 1st still. The others are following up 1km curve gradually in a group while interacting among them.
Monday, August 18, 2025
Sum of Magnitude per 1day in 千葉県南東沖
Sum of Magnitude per 1day in 千葉県南東沖（Southeast offshore Chiba Pref.）
Area map of 千葉県南東沖
Area map of 千葉県南東沖（Southeast offshore Chiba Pref.）is defined for epicenter's analysis as below,
Counts of occurrence per depth in 茨城県南部
Counts of occurrence per depth in 茨城県南部（Southern Ibaraki Pref.）is shown as below graph,
Even though 1km count is the 2nd, the occurrence has stopped since 2000. The sum of 10km/20km is only 3%. So, recently 40km-50km earthquakes make up the majority. It seem to me that there might remain the residual cracks of the pacific plate around this area. In comparison to before and after M9.0, the depth distribution in 茨城県北部 shifted to shallower greatly, while only minor change was observed in 茨城県南部 . It seems to suggest my idea. 
Saturday, August 16, 2025
Area map of 茨城県南部
Area map of 茨城県南部（Southern Ibaraki Pref.）is defined for epicenter's analysis as below,
Friday, August 15, 2025
Counts of occurrence per depth in 茨城県北部
Counts of occurrence per depth in 茨城県北部（Northern Ibaraki Pref.）is shown as below graph,
1-30km curves had the longest silent terms until right after M9.0 (Great East Japan Earthquake)'s aftershocks (For 20km, the 1st/2nd silent terms continued). They seem to be ones of the sign of the M9.0 even though the epicenter is far from this area. The M9.0 made 10-30km counts jump up. In result, 10km's rank jumped up from the 11th to the 1st.
- 1km (red)…The count is the 2nd. There was M6.3 in 1923 as the largest one of 1km. Before and after the M6.3, the rapid increase was continuing. The M6.3 itself was the one of the aftershocks of M7.9 of Great Kanto Earthquake, occurred in just after it western area of Kanagawa Pre. in 1923. So, these many earthquakes of 1km including the M6.3 seem to be the foreshocks of the M7.9. After it, the silent terms became longer gradually. The longest silent term was occurred between 1981-2011. It was interrupted by M9.0 of Great East Japan Earthquake. After the M9.0, the increase of 1km was far less than 10km. In result, the count rank went down from the 1st to 2nd.
- 10km(yellow)…The count is the 1st. The count rank was the 9th to 10th between 1940-2011. But, by the M9.0, the count was increased rapidly. M7.0 was occurred after one month later as the greatest aftershocks of the M9.0. On the way to the M7.0, M6.1 was occurred on the twin junction between 10km / 90km. Though 10km/90km far away, the reason why the junction could be formed between them that the cause was the M9.0 far outside from this area.
- 50km(light blue)…The count is the 3rd. Before and after M7.9 of Great Kanto Earthquake in 1923, the count increased smoothly. Between 1930-now, the count rank has been almost kept as the 3rd. Both M6.1 of 50km in 1923 and M6.5 of 50km in 1924 were occurred as the aftershocks of the M7.9. The M6.1 was occurred around the twin junction between 50km/40km. The largest magnitude is M6.5 both in 1924 and in 1930.
- 60km(blue)…The count is the 4th. 60km curve has been following behind a little bit. The largest magnitude of 60km is M5.8 in 1934.
- 40km(green)…The count is the 5th. 40km curve was overlapped with 50km curve until around 1934. After the separation from 50km curve, it was overtaken by 60km curve. Then, the silent terms became longer gradually. The longest silent term is between 1978-1991. The largest magnitude of 40km is M5.4 in 1954.
- 70km(purple)…The count is the 6th. 70km curve was overlapped with 60km curve until around 1935. After the separation from 60km curve, it was overtaken by 60km curve. Then, the silent terms became longer gradually. The largest magnitude of 70km is M5.6 in 1935.
- 90km(brown)…The count is the 7th. 90km curve was following behind 70km curve. The largest magnitude of 70km is M5.4 in 2022.
- 20km(orange)… The count is the 8th. Before the M9.0 in 2011, 20km curve was almost overlapped with 10km curve. As same as 10km, the longest silent term was occurred between 1973-2011, interrupted by the M9.0's aftershock. The largest magnitude of 20km is M4.7 in 1948.
- 30km(yellow green)…The count is the 8th. Before the M9.0 in 2011, 10km/20km curves was following 30km curve behind. As same as 1km-20km, the longest silent term was occurred between 1986-2011, interrupted by the M9.0's aftershock. These long silent terms seem to be ones of sign of the M9.0. The largest magnitude of 30km is M5.5 in 1925.
- others… omitted.
Wednesday, August 13, 2025
Subscribe to:
Comments (Atom)
-
In Chugoku Area, Correlation between T (Occurrence Time) and D (Depth) in 19set/163set among 11 epicenters are more than 0.9900. The major ... -
MD-T chart in 釧路地方中南部 (Central Southern Kushiro region) MD values between 1978-2002 were going toward the shallow depth around 2km. In 200...
