MD-T chart in 釧路地方中南部

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 2004/11/29, M7.1 of 50km depth was occurred as Kushiro Earthquake. After it, Earthquakes of 1km have increased in 2015. In 1961/8/12, M7.5 of 50km depth was occurred also (No proper name because of no serious damage).

MD chart in 釧路地方中南部

MD chart in  釧路地方中南部 (Central Southern Kushiro region) 

Oakan-dake, Meakan-dake, and Anosanupuri are volcanoes.

Dragon chart in 釧路地方中南部

Dragon chart in 釧路地方中南部 (Central Southern Kushiro region) 

Sum of Magnitude per 1day in 釧路地方中南部

Sum of Magnitude per 1day in 釧路地方中南部
 (redefined rectangle area of Central Southern Kushiro region) 

note : Horizontal axis isn't linear. Data of epicenters of unknown details (with no magnitude data) are omitted to make the colors of depths clear. The max magnitude is M7.5 of 100km depth of Kushio-oki in 1993/1/15. M7.1 of 50km depth of Kushiro-oki (called Kushiro-oki Earthquake) in 2004/11/29 made the peak of Sum of Magnitude of 50km(light blue).

Distribution of Magnitude in 釧路地方中南部

 Distribution of Magnitude in 釧路地方中南部
 (redefined rectangle area of Central Southern Kushiro region) 

M<1.0 (ln Mg<0) often occurs around volcanoes. In this case, 2 epicenters of M0.8 / M0.9 are located around Atosanupuri volcano (See MD chart about the location).
 

Distribution of Depth in 釧路地方中南部

Distribution of Depth in 釧路地方中南部 (Central Southern Kushiro region)

 

Area map of 釧路地方中南部

 Area map of 釧路地方中南部 (Central Southern Kushiro region) is defined for epicenter's analysis as below,

 

Counts of occurrence per depth in 釧路地方北部

Counts of occurrence per depth in 釧路地方北部 (North Kushiro region) is shown as below graph, 

1km (red)…This count of the earthquakes is the 1st one. There was the longest silent term between 1967-2002 (35 years). After it, there was a rapid increase of the count and 5 years silent term. Then the count is still increasing with high frequency. On the way, the curve have overtaken 10km. The max magnitude is M6.1 in 1938.

10km(yellow)…This count is the 2nd as overtaken by 1km when there was the longest silent term between 1988-2015 (27 years). The max magnitude is M6.5 in 1967. Before it, there was a rapid increase after M6.3 in 1959. M6.5 is the largest one of all depths also. 

20km(orange)…This count is the 3rd. The curve was following 10km with the rapid increase in 1959. But, there is no additional occurrence of 20km after M3.7 in 1971. The max magnitude is M5.6 in 1956.

30km(yellow green)…This count is the 4th. The latest occurrence was in 1968 (the magnitude was unknown). The max magnitude is M6.1 in 1959 as same as 1km. So, it seems there has been enough energy to grow up the count. But, the count is in the longest silent term since 1968 (57 years and more).

40km-80km … No occurrence.

90km(brown)… Only once occurrence in 1929 as unknown details (no magnitude data).

110km/130km/140km/150km…New comers since 1998. The max magnitude of them are only M3.5-M4.4. The counts are only 1-3 times.

Counts of occurrence per depth in 十勝地方南部

Counts of occurrence per depth in 十勝地方南部 (South Tokachi region) is shown as below graph, 

note : There are not included of all depths to avoid too complicated curves. 

• 1km (red)…This count of the earthquakes is the 1st one. There was a rapid increase of the count after M6.0 in 1927. But, the the increase has stopped in 1982. The max magnitude is only M5.4 in 1928.
• 50km(light blue)…This count is the 2nd. Around 50km in depth, the counts are larger than others of shallow depths.There were some long silent terms. The longest one was between 1941-1950, and the 2nd one was between 1989- 1998. After both long terms, the counts had increased faster. After overtaking the curves of 60km/70km, there was the max magnitude of M6.1 in 2012.
• 60km(blue)…This count is the 3rd. After M6.7 in 1970, the curve's slope became steeper. The curves of 60km/70km have been overtaken by each other. Since 2004, 60km's curve overtakes 70km's one. Both of them haven't been affected by M6.1 of 50km in 2012. The max magnitude is M6.7 in 1970, and it is also the max in all depths. 
  
• 70km(purple)…This count is the 4th. The max magnitude is M5.6 in 1979. The curve seems to overtake 60km again in future.
• 40km(green)…This count is the 5th. The count of 40km/30km were increased by M6.7 of 60km in 1970 rapidly. But, the curve of 30km couldn't overtake 40km. The max magnitude is M6.0 in 1927.
• 100km(gray) …This count is the 6th. After M6.5 in 2013, the curve overtook 30km, then 80km also. The max magnitude is M6.5 in 2013.
• 80km(navy blue)…This count is the 7th. The curve has overtaken by 100km in 2024. The max magnitude is only M5.6 in 1925.
• 30km(yellow green)…This count is the 8th.The max magnitude is only M5.0 in 1931.     
• 10km(yellow)…This count is the 9th even though shallow depth. The last occurrence was in 2011 before M6.1 of 50km in 2012. The max magnitude is only M5.0 in 1941.
• 20km(orange)…This count is the 10th even though shallow depth. The last occurrence was in Jun/1970 after M6.7 of 60km in Jan/1970 . The max magnitude is only M5.1 in 1952.
  
• 120km(gray) …This count is the 11th. The max magnitude is M6.6 in 1987.

Counts of occurrence per depth in 十勝地方中部

Counts of occurrence per depth in 十勝地方中部 (Middle Tokachi region) is shown as below graph, 

note : There are not included of all depths to avoid too complicated curves. 

• 1km (red)…This count of the earthquakes is the 1st one. There was a rapid increase of the count after M6.2 in 1921. But, the the increase has stopped in 1972. The max magnitude is only M4.9 in 1934.
• 100km(gray)…This count is the 2th. Around 100km in deep, the counts are larger than others of shallow deeps.The max magnitude is M6.5 in 2013. This value is the max of all depths also.         
  
• 90km(brown)…This count is the 3rd as same as 120km. After M6.5 of 100km in 2013, there was a long silent term between 2014-2021. In result, the count hasn't increased so far though the curve seems to follow 100km. The max magnitude is M5.1 in 1953.
• 80km(navy blue)…This count is the 4th following 90km. But, the the increase has stopped in 2022. The max magnitude is M5.9 in 1942. Because of the high value of the max magnitude, the count may become more later.
• 110km(blue) …This count is the 6th. The max magnitude is M5.2 in 1997, and the count curve rises up rapidly in recent. The curve may catch up with 100km.
• 10km(yellow) …This count is the 10th. There was the longest silent term between 1972-2003(21 years).  After it, the count increases little bit, and the count is staying low still.
• 20km-50km…These counts are the 11th-13th. Unless there is some big earthquake, the ranks should stay lower than ones of around 100km. 40km's max magnitude is M6.0. So, the count may become easier than others of 20-50km.  

Counts of occurrence per depth in 十勝地方北部

Counts of occurrence per depth in 十勝地方北部 (North Tokachi region)  is shown as below graph,

note : There are not included of all depths to avoid too complicated curves. 

• 1km (red)…This count of the earthquakes is the 1st one. There was a rapid increase of the count after the longest silent term of 1km between 1972-2003 (for 21 years) by M6.8 of 30km in 1931/M6.9 of 70km in 1932. The max magnitude of 1km is M5.7 in 1924. Total max value for all depth is M6.4 of 60km in 1931. After it, there was the 2nd longest silent term of 1km between 1931-1950 (for 19 years). Even though almost 100 year ago, the record has been kept. The count is still growing.
• 10km (yellow)…This count of the earthquakes is the 2nd now. But, the 1st record of the initial occurrence was not so old, in 1969. On addition to it, the 2nd occurrence was in 2000 with 31years silent term. Maybe due to the short term, the max magnitude is only M4.6 in 2020. The count is still on going increasing following 1km's curve. 
  
• 20km-80km…These counts are only 2-4 times. As described above, M6.4 of 60km in 1931 is  the max value for all depths. 
  
• 90km(brown)…This count is the 3rd as same as 120km. But, the last occurrence was in 2012 (13 years ago). There was a little bit rapid increase after the overtaking the curve of 140km until the last occurrence. The max magnitude is only M3.9 in 1996.
• 120km(gray with dot line)…This count is the 3rd as same as 90km. The curve overtook once when it had overtook the curves of 140km&100km in 1972. But, after the long silent term between 1972-1999, the count growth of 90km was more and has overtaken. The last occurrence was in 2015 (10 years ago). The max magnitude is M5.8 in 1944.
• 110km(gray)…This count is the 5th. The max magnitude is M6.3 in 1999, and the value is the 2nd one for all depth. Due to the large Magnitude, the count is still increasing. The rank of count may become higher than 90km/120km within several years. 
  

Counts of occurrence per depth in 日高地方

Counts of occurrence per depth in 日高地方 (Hidaka region) is shown as below graph,

note : There are not included of all depths to avoid too complicated curves. 

• 1km (red)…This count of the earthquakes is the 1st one. There was a rapid increase of the count by M6.8 of 30km in 1931/M6.9 of 70km in 1932. After the pace down gradually, there was a speed up by M6.8 in 1944. This M6.8 is the max magnitude of 1km. There was a long silent term of 1km between 1964-1968 (4 years). Before 2 months ago of the end of the term, M6.8 of 50km was occurred in Sep/1968. 2 years later, M6.7 of 60km was occurred also. These earthquakes seem to have accelerated the count of 1km. The increase might be stopped by 2 earthquakes of M6.9 of 130km in 1981/M7.1 of 40km in 1982. The 2nd longest silent term was occurred between 1982-1995. The longest one continued to occur between 1995-2011. As described above, M7.1 of 40km is the max magnitude in this area. After the other long silent term between 2011-2018, M6.7 of 40km was occurred in Sep/2018 as just before the end of it. Since then, the frequency has increased a little bit more.
• 60km(blue)…This count of the earthquakes is the 2nd one. It is far more than them of 10km/20km. Such reversal status may become the trigger of avalanche phenomenon to release the unbalance of the potential energy. The count seems to accelerate the count when it takeovers them of 20km/40km/50km. The max magnitude is M6.7 in Jan/1970.    
  
• 70km(purple)…This count of the earthquakes is the 3rd one. The curve overtook 50km/60km. But, It has been overtaken by 60km at last. The max magnitude is M6.9 in Nov/1932.  
• 50km(light blue)…This count of the earthquakes is the 4th one. Though the curve was overlapped with it of 40km, it just barely succeed in keeping the count raking as 4th. The max magnitude is M6.8 in Sep/1968.     
  
• 40km(green)/30km(yellow green)…The curve 40km(green) has almost been keeping higher rank than 30km's one. There has been 3 major rapid increases in common with 40km/30km. The 1st was M6.7 of 60km in 1970, the 2nd was M7.1 of 40km in 1982, and the 3rd was M6.7 of 40km in 2018. M7.1 is the max Magnitude of 40km. On the other hand, the max magnitude of 30km is M6.8 in 1931 (far older than 3 major increases). The counts of 50km/40km/30km are in reverse status against the natural one with low potential energy. Further more, the difference of them are few. It may show there should be a big turning the table in future.  
• 10km(yellow)…This count of the earthquakes is the 9th (lowest in 1km-90km). It seems there should be huge stress stocking around there.
• Others…100km-120km's curves are still extending actively also.  
  

In wide range depths, the earthquake occurrences are very active. So, we should need to watch them carefully.

Counts of occurrence per depth in 胆振地方

Counts of occurrence per depth in 胆振地方 (Iburi region) is shown as below graph,

note : There are not included of all depths to avoid too complicated curves. 

• 1km (red)…This count of the earthquakes is the 2nd one. But, the max Magnitude is M5.6 in 2014. The max of all depths in this area is M6.7 of 40km in 2018 (named "The 2018 Hokkaido Eastern Iburi Earthquake"). But, there were not rapid increase of 1km/10km, but of 30km/40km. There were 2 major rapid increases of 1km/10km. One was in Jan/1944 related with the growth of M't Showa-shinzan, which is very famous as newborn volcano in Showa era. As the earthquakes were caused by volcano activity, most of the Magnitudes were unknown, and no rapid increase of other depth like as 10km or so on.  The another rapid increase was occurred in Mar/2003. It was caused by the volcano activity of M't Usu eruption. After 2 rapid increases, the increase of 1km count becomes very slow. 
  
• 10km (yellow)…The count has become the 1st one after M't Usu eruption in May/2003. These earthquakes were occurred as the advance activity of the eruption. The max Magnitude was M4.9 as one of the volcanic earthquakes of M't Usu in Apr/2000.
• 30km (Yellow Green)… The count is the 3rd. The rapid increase was occurred continuously. The 1st one was caused by M5.1 of 30km in Jul/2017. The second one was occurred just after the M6.7 of 40km. By the 1st increase , the count of 30km had approached to the count of 21 of 130km. The below graph is the count per depth in 胆振地方.Orange line shows the counts just before M6.7, and Blue one shows the current one.

   By 1st rapid increase of 30km, the count had caught up with the one of 130km as 21 counts. In result of M6.7 in 2018, the counts of 20km-30km has jumped up (especially 30km). This change seems to be the adjustment against the concave of curve around 30km's peak caused by the rising tail around 130km's one. The touch up with the count to 130km may have become the trigger of M6.7 of 40km for the adjustment.

 

 The next graph shows the comparison of the counts  before and after M9.0 in 2011. The curve shapes may be the final ones. It seems Avalanche caused by unbalance potectial energy makes the surface flat. (though the energy from deeper to shallower as a tendency).

 

 

 

• 40km (Green)… The count is the 5th. The below list shows the counts of 20km/30km/40km/130km around count of 22. Red font shows the data of M6.7 of 40km in 2018/9/9. As wrote above, the same count may be the trigger of M6.7 of 40km. Then the count of 40km had the rapid from 5 to 21 almost in 1 hour. The count of 20km reached from 18 to 21 about 3days later. 

• 20km (Orange)… The count is the 5th. The curve of 130km is approaching. The catch up with them might become some trigger of the increase of 20km.
• 130km (gray) … The count is the 6th. It is still increasing continuously.
  

Counts of occurrence per depth in 網走地方

Counts of occurrence per depth in 網走地方 (Abashiri region) is shown as below graph,

note : There are not included of all depths to avoid too complicated curves. 

• 1km (red)…This count of the earthquakes is the most one. But, the max Magnitude is M5.1 in 1938 (The max of it in this area is M6.5 of 10km in 1967). The increase was slow down after M6.5 (10km in 1967), and there was the longest silent term between 1975/2002. After it, the counts started rapid increasing in Jun/2004. It may be related with M7.1 (釧路沖地震) in the rapid increase of 1km 2004 as the sign of M7.1 even though the epicenter far from 網走地方. The increasing count of 1km is still continuing. There will be the next great earthquake more than M6 because of the accumulation of many earthquakes since M5.1 in 1938.   
  
• 10km (yellow)…The count is the 2nd after the rapid increase of 1km in 2004.  M6.5 in 1967 is the greatest one in this area, and there was the rapid increase of count over the count curve of 10km. But, as no greater one there has been, the count has been changed to 2nd by the rapid increase of 1km in 2004 related with 釧路沖地震. The count is still continuing. But, not so rapid against the one of 1km. So, the count can't follow up the one of 1km.
  
• 20km (orange)…The count is the 3rd after the rapid increase of 1km in 2004 also. There was the quick step up of the count after M6.1 of 30km in 1959, and then there was the rapid increase of the count in 1965. It was about 2 years before M6.5 (10km) in 1967. By this M6.5, the count has one more rapid increase. But, after it, there was the longest silent term of 38 years between 1978/2016. Still, no more occurrence in 20km.　  
  
• 120km-160km(gray)…The minor peak of counts per depth around 120km. And there was M6.1(160km) in 1997. So, there may be increase the counts of them.
  

Counts of occurrence per depth in 北見・紋別地方

Counts of occurrence per depth in 北見・紋別地方 (Kitama & Monbetsu region) is shown as below graph,

Colored labels show the data of Max Magnitude/depth/date/count per each depth.

There was only data of 1km before M5.1 (190km) in 1944. After the M5.1, the max Magnitude of all data had been broken the record of them as below,

• Max=M4.9 (  1 km) : 1919-1944
• Max=M5.1 (190km) : 1944-1966
• Max=M5.2 (250km) : 1966-1990
• Max=M5.4 (170km) : 1990-2025

10km (count=1) was occurred in 2007 after M5.4 (170km/count=1) and 170km (count=2) about 2 years later. 10km (count=2-9) was occurred in 2009 including M4.2 (10km/count=4, max of 1km). At the count=5 of 10km, it became the same one of 1 km. The common count may be the trigger timing of the rapid increase of 10km. After 2 long silent times of 4 years/5 years, the count of 10km increased rapidly again in 2023.  

Since of no record update in 1km there has been, M4.9 is still the max value in 1km data. 3 months later, the 2nd longest silent term of 1km finished by the count =6 of 1 km. After the 1st longest silent term (1926-1976) and the 2nd one (1976-2024), there might be occurred the rapid increase of 1km's count in the near future.

Counts of occurrence per depth in 宗谷地方・宗谷海峡

Counts of occurrence per depth in 宗谷地方・宗谷海峡 (Soya region & Soya Strait) is shown as below graph,

note : There are not included of all depth to avoid too complicated curves.

• 1km(red)…This count of the earthquakes is the most one. But, the max Magnitude is only M5.6 since 1932 (The max of it in this area is M6.1 of 340km/350km in 1951/1992). The counts had have been increased rapidly after the long silent terms of it. The longest one was between 1993/2008, and the rapid increase count of 1km/10km was occurred in 2009 (next year of the end of the longest silent term). The rapid increase of the count of 10km was also occurred with it of 1km in 2022. 10km's rapid increase had been started just before 1km's one. It seems to show the tendency of the bringing the earthquake energy to shallower depth. 
• 10km(yellow)…The count is the 2nd. In 2022 increase, the curve approached to the one of 1km. The max Magnitude of 10km is M5.4 in 2022. The count increase of 1km/10km was occurred by this M5.4.
• 20km(orange)…The count is the 3rd now. The longest silent term is between 1919-1998 (Japan Meteorological Agency had started the observation of earthquakes in 1919).  The curve crossed over 1km's one between 2000-2010, and 2curves were overtaking and being overtaken after it until M5.4(10km) in 2022.
• 30km(yellow green) …The count is 4th. But, the increase has stopped since 2016. After it, the longest silent term has become about 9 years. It may be the sign of the next big earthquake or the continuous earthquakes.
• 40km(green)…The occurrence was only M4.3 in 1978.
• 320km(gray)…The count is 5th. Even though the count is only 6, the max Magnitude is M5.9. 
• 330km/340km/350km(gray)…The counts are 1-4. The max Magnitude are M6.0/M6.1. M6.1(340km/350km) is the max value in this area. 

Counts of occurrence per depth in 上川・留萌地方

Counts of occurrence per depth in 上川・留萌地方 (Kamikawa,Rumoi region) is shown as below graph,

note : There are not included of all depth to avoid too complicated curves.

• 1km(red)…This count of the earthquakes is the most one. But, the max Magnitude is only M5.6 since 1932 (The max of it in this area is M6.5 of 260km in 1942). So, the max value should become more than M5.6. In 2022, M5.4 of 1km has been occurred as a series of earthquakes including 10km. This may be the sign of the next bigger one.
• 10km(yellow)…The count is the 2nd. Because of the coming closer to 1km curve, the linkage with it may become easier than before. The rapid increase began after the long silent terms of 1922-1955/1955-1986 (1st/2nd longest). There were the preceding sequences of 20km(orange) before them of in 1995/2004. Especially the one of them in 2004 was included with M6.1. Between 2 continuous ones, there was the long silent term of 1997-2002.
  
• 20km(orange)…The count is the 3rd. The remarkable increase began after the longest silent term of (1919)-1968 (Japan Meteorological Agency has no quantitative data before 1919).
• 30km(yellow green) …The count is 4th. But, the increase has stopped since 2016. After it, the longest silent term has become about 9 years. It may be the sign of the next big earthquake or the continuous earthquakes.
• 40km/50km…40km is only once. 50km is no record.
• Ohters…The count of 150km/160km(gray) are 5th. Except M6.1 of 10km, all the greater earthquakes were occurred in far deeper area of 180km/200km/260km. 

Because of keeping the order of depth in the counts as shallower ones more, the status of earthquake occurrence is more stable one especially in shallow area. But, the big earthquakes more than M6 must be occurred in shallow area (1km/10km/etc.) as the order changer of them. Because 1km's huge earthquakes are the one of the final release of the stocked earthquake energy of deeper area.    

 

Counts of occurrence per depth in 渡島・檜山地方

Counts of occurrence per depth in 渡島・檜山地方 (Oshima,Hiyama region) is shown as below graph,

1km's count was the most one before M't Usu's eruption in 2000. After it, 10km's one becomes the most. It was occurred after the longest silent term (almost seven years) of 1km earthquakes. 10km's curve increased also by it, and there had been increased between 1995/11-2000/3. The increase of 10km seems to be occurred by M6.3 (20km) in 1993/8. Addition to it, M6.3 in 1993 may be occurred M6.1 (120km) in 1992. They had performed one chain reaction. Long silent terms were often found on the curves of shallow depths like as in 1km/10km/20km especially, and the rapid increase of the counts are occurred after them with high accuracy. In curves of deeper ones, the interval themselves are long in general.  So, there should be difficult to be found out the longer silent term than it.   

Counts of occurrence per depth in 石狩・空知・後志地方

Counts of occurrence per depth in 石狩・空知・後志地方 (redefined rectangle area of Ishikari,Sorachi,Shiribetsu region) is shown as below graph,

Before M6.7 (1km) in 1947, there was earthquake swarm of unknown details in Jan/1944. After M6.7 and the aftershock, log of the counts of 1km occurrence is linear against the date.Before M6.7 of 40km in 2018, there was earthquake swarm of 30km in Jul/2017. There was long quiet period of 40km between 1947-2018 also. In 2017, the count of 30km preceded it of 20km.    
 

Counts of occurrence per depth in 胆振地方

In 胆振地方 just before M6.7 in 2018/9/6, Distribution of Depth (brown line) was as below,

After M6.7, the new peaks has grown up around 30-40km depth mainly. Before M6.7, there were the even peaks of 30km/130km. By M6.7, the peak of deep area has been shifted to shallow area. M6.7's epicenter was in 40km. If the epicenter were shallower more, the curve might have become more simple like as trapezoid with downhill in 三陸沖. The even peaks of 30km/130km seems to be the trigger of avalanche from the deep area to shallow area.

To make clear the relationship among the count changes per depth as  time sequence, I tried making the graph of Counts of occurrence per depth for the data in 胆振地方 as below,

Note : There are not all data of each depth. Some depth data are omitted.

Intersections among the lines between of the different depths seem to be the changing points of the pattern of the count curves per depth. Counts of 22 times of 4 lines of 20km(orange)/30km(yellow green)/40km(green)/130km(gray) are crossed in narrow area around the time of M7.6. Towards Year 2000, there was the first jump of 20km curve, the 2nd jump of 10km, and 3rd jump of 1km. The jumps had moved to deeper area to shallower area. The close-sets between 2 lines seem to becoming the changing patterns as like circled points. 

So, this graph may be useful for the prediction of the sudden increasing of counts (it may sometimes mean great earthquakes with many aftershocks). The long blank times until the next occurrence can be checked in the graph also. 

In 三陸沖, the graph of counts of occurrence per depth is as below,

The graph is more simple because of less depths.

Counts of 1km(red)/10km(yellow) have been overtaking and being overtaken. After jumping up, the line becomes flat, or tilted straight lines.The previous small jumping up were caused the next change in the other lines.