List of foreshocks and aftershocks of the 2011 Tōhoku earthquake

This is a list of foreshocks and aftershocks of the 2011 Tōhoku earthquake. Japan had experienced 900 aftershocks after the M9.1 earthquake on March 11, 2011 with about 60 aftershocks being over magnitude 6.0 and three over magnitude 7.0. For conciseness, only earthquakes with magnitudes greater than 7.0 or an intensity greater than lower-6 on the shindo scale are listed here. Mw refers to the moment magnitude scale, while Mjma, Mjma, or Mj refer to the Japan Meteorological Agency seismic intensity scale.

Visualization of intensity of aftershocks in the first few days
Map of aftershocks until March 14 (first 4 days)

Foreshocks
Japan Time Magnitude Coordinates Depth Intensity (shindo)[1] Comment
2011-03-09 11:45 Mw 7.3, Mj 7.3[2] 38.424°N 142.836°E / 38.424; 142.836 32 km[USGS 1] lower 5

The source was estimated to have a length of 28.7 km and a width of 53.2 km with a slip of 1.25 m.[3] Caused a 55 cm tsunami.[4]

2011-03-10 06:23 Mw 6.4, Mj 6.8 38.171°N 143.043°E / 38.171; 143.043 9 km 4 Caused 11 cm Tsunami.[5]

Main shock
Japan Time Magnitude Coordinates Depth Intensity (shindo)[1] Comment
2011-03-11 14:46 Mw 9.1, Mj 8.4[2] 38.322°N 142.369°E / 38.322; 142.369 29 km[USGS 2] 7
Further information: 2011 Tōhoku earthquake and tsunami
15,899 deaths,[6] 2,529 people missing[7] tsunami, nuclear incidents.

Aftershocks
Japan Time Magnitude Coordinates Depth Intensity (shindo)[1] Comment
2011-03-11 15:08 Mj 7.4[1] 39.82°N 139.025°E / 39.82; 139.025 32 km[1] lower 5
2011-03-11 15:15 Mw 7.9, Mj 7.6[1] 36.27°N 141.14°E / 36.27; 141.14 43 km[USGS 3] upper 6
2011-03-11 15:25 Mw 7.7, Mj 7.5[1] 38.05°N 144.59°E / 38.05; 144.59 19 km[USGS 4] 4
2011-04-07 23:32 Mw 7.1, Mj 7.2[1] 38.253°N 141.640°E / 38.253; 141.640 42 km[USGS 5] upper 6
Further information: April 2011 Miyagi earthquake
4 dead, 100+ injured, large scale power outage in Tōhoku region.[8][9]
2011-04-11 17:16 Mw 6.6, Mj 7.0[1] 37.007°N 140.477°E / 37.007; 140.477 10 km[USGS 6] lower 6
Further information: April 2011 Fukushima earthquake
6 dead, several injured, localized power outage and landslides in Iwaki, Fukushima.[10]
2011-04-12 14:07 Mj 6.4[1] 37.052°N 140.643°E / 37.052; 140.643 15 km[1] lower 6
2011-07-10 09:57 Mw 7.0, Mj 7.3[1] 38.040°N 143.287°E / 38.040; 143.287 23 km[USGS 7] 4 10 cm of tsunami in Sōma and Ōfunato.[11]
2012-12-07 17:18 Mw 7.3[1] 37.8°N 144.2°E / 37.8; 144.2 49 km (JMA)[1]
36 km [USGS 8]		 lower 5
Further information: 2012 Kamaishi earthquake
Tsunami under 1 meter. Considered an aftershock by the National Earthquake Information Center in Colorado, USA.[12]
2013-10-26 02:10 Mw 7.1 37.170°N 144.665°E / 37.170; 144.665 10 km [USGS 9] 4 Tsunami[13]
2016-11-22 05:59 Mw 6.9 37.393°N 141.387°E / 37.393; 141.387 9 km
Further information: 2016 Fukushima earthquake

The following earthquakes are possibly related to the 2011 Tōhoku earthquake. However, agreement toward the relationships has not been reached among the researchers.[14]

Japan Time Magnitude Coordinates Depth Intensity (shindo)[1] Comment
2011-03-12 03:59 Mw 6.3, Mj 6.7[1] 37.02°N 138.36°E / 37.02; 138.36 8 km[1]
2 km[USGS 10]		 upper 6 Possibly a triggered earthquake.[15][16]
2011-03-12 04:31 Mj 5.9[1] 36.948°N 138.572°E / 36.948; 138.572 1 km[1] lower 6 Possibly a triggered earthquake.[16]
2011-03-12 05:42 Mj 6.3[1] 36.972°N 138.59°E / 36.972; 138.59 2 km[1] lower 6 Possibly a triggered earthquake.[16]
2011-03-15 22:31 Mw 6.0, Mj 6.4[2] 35.29°N 138.54°E / 35.29; 138.54 9 km[USGS 11] upper 6 50 injured. Power outage.[17] Near presumed location of magma chamber of Mount Fuji.
Sinistral strike-slip fault.[18] Possibly a triggered earthquake.[19]

References

USGS
  1. Magnitude 7.2 – NEAR THE EAST COAST OF HONSHU, JAPAN Archived 2011-03-10 at the Wayback Machine. Earthquake.usgs.gov. Retrieved on 2011-04-12.
  2. Archived 2011-03-13 at the Wayback Machine. Earthquake.usgs.gov (2011-03-14). Retrieved on 2011-04-12.
  3. : Preliminary Earthquake Report: NEAR THE EAST COAST OF HONSHU, JAPAN Archived 2011-04-12 at the Wayback Machine, USGS Earthquake Hazards Program (2011-03-11). Retrieved on 2011-04-12.
  4. USGS Earthquake Hazards Program: Preliminary Earthquake Report: OFF THE EAST COAST OF HONSHU, JAPAN Archived 2011-04-12 at the Wayback Machine. Neic.usgs.gov (2011-03-11). Retrieved on 2011-04-12.
  5. Magnitude 7.1 – NEAR THE EAST COAST OF HONSHU, JAPAN Archived 2011-04-14 at the Wayback Machine. Earthquake.usgs.gov. Retrieved on 2011-04-12.
  6. Magnitude 6.6 – EASTERN HONSHU, JAPAN. Earthquake.usgs.gov. Retrieved on 2011-04-12.
  7. "Magnitude 7.0 - Off the East Coast of Honshu, Japan 2011 July 10 00:57:12 UTC". Archived from the original on 2011-10-15. Retrieved 2017-07-23.
  8. https://earthquake.usgs.gov/earthquakes/eventpage/usc000e5n4#summary
  9. https://earthquake.usgs.gov/earthquakes/eventpage/usc000kn4n
  10. USGS Earthquake Hazards Program: Preliminary Earthquake Report: NEAR THE WEST COAST OF HONSHU, JAPAN. Neic.usgs.gov. Retrieved on 2011-04-12.
  11. USGS Earthquake Hazards Program: Preliminary Earthquake Report: EASTERN HONSHU, JAPAN. Neic.usgs.gov (2011-03-15). Retrieved on 2011-04-12.

Other
  1. 震度データベース検索 Archived 2013-02-13 at the Wayback Machine. Japan Meteorological Agency. Retrieved on 2013-02-18.
  2. 「平成23 年(2011 年)東北地方太平洋沖地震」について（第28 報）(Press Release), 25 March 2011. Published by Japan Meteorological Agency.
  3. "Archived copy". Archived from the original on 2012-01-19. Retrieved 2011-12-02.CS1 maint: archived copy as title (link)
  4. 「日本付近で発生した主な被害地震（平成８年以降）」JMA, Access date March 5, 2017
  5. 平成23年3月10日（06時23分）の三陸沖の地震で発表した津波注意報について JMA
  6. "Damage Situation and Police Countermeasures... 8 March 2019" National Police Agency of Japan. Retrieved 13 March 2019. (from "deaths" template)
  7. "Damage Situation and Police Countermeasures... 8 March 2019" National Police Agency of Japan. Retrieved 13 March 2019. (from "missing" template)
  8. asahi.com（朝日新聞社）：東北の広域停電、完全復旧めどたたず 余震死者２人 – 東日本大震災. Asahi.com (2011-04-08). Retrieved on 2011-04-12.
  9. ７日の地震 ４人死亡１４１人けが NHKニュース Archived 2011-04-11 at the Wayback Machine. .nhk.or.jp. Retrieved on 2011-04-12.
  10. CNN Wire Staff (11 April 2011). "At least 6 killed in new Japan earthquake". articles.cnn.com. CNN World News. Archived from the original on 2 June 2011. Retrieved 2011-04-23.
  11. http://www.asahi.com/national/update/0710/TKY201107100080.html
  12. Japanese Quake Stirs On-Air Alarm, but No Damage to Nuclear Plants Is Reported, New York Times
  13. http://www.asahi.com/articles/TKY201310260033.html?ref=com_top6
  14. 静岡東部の震度６強、東海地震誘発せず…専門家 : 科学 : YOMIURI ONLINE（読売新聞）. Yomiuri.co.jp. Retrieved on 2011-04-12.
  15. 2011年3月 東北地方太平洋沖地震 | 広報アウトリーチ室 Archived 2011-04-18 at WebCite. Outreach.eri.u-tokyo.ac.jp. Retrieved on 2011-04-12.
  16. 「平成23年（2011年）東北地方太平洋沖地震」について（第38報）(Press Release), 12 April 2011. Published by Japan Meteorological Agency. Retrieved on 2013-02-17.
  17. http://www.pref.shizuoka.jp/kinkyu/documents/0315toubujisin5.pdf
  18. ２０１１年３月１５日静岡県東部の地震の評価. Jishin.go.jp. Retrieved on 2011-04-17.
  19. 東日本沖巨大地震. Sk01.ed.shizuoka.ac.jp. Retrieved on 2011-04-12.
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