1968 Tokachi earthquake

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1968 Tokachi earthquake
Date May 16, 1968
Origin time 0:49 UTC [1]
Magnitude 8.3 Mw [1]
Depth 26 km (16 mi) [1]
Epicenter 40°54′N 143°21′E / 40.90°N 143.35°E / 40.90; 143.35
Countries or regions Japan
Casualties 47 killed

The 1968 Tokachi earthquake (1968年十勝沖地震 Sen-kyūhyaku-rokujūhachi-nen Tokachi-oki Jishin) occurred on May 16, 1968 at 0:49 UTC (09:49 local time). The earthquake was located in the area offshore Aomori and Hokkaido. The magnitude of this earthquake was put at Mw 8.3, or Ms ~8.0.[1][2] The intensity of the earthquake reached shindo 5 in Aomori, Aomori and Hakodate, Hokkaido.[3]

Geology

This earthquake was located near the junction of the Kuril Trench and the Japan Trench. It is an interplate earthquake.[4] The focal mechanism of this earthquake shows movement on a thrust fault with a considerable slip-strike component.[2] The sum of interplate seismic moment release by seismic and aseismic faulting in this earthquake is about 28×1020 N m. 1960s was noted as one of the peak periods of interplate seismic moment release in the offshore Sanriku region.[5]

Damage

Heavy rain occurred due to a low pressure days before the earthquake and aggravated the damage. The earthquake caused 47 deaths.[6] In Hokkaido, building damage was reported. A 4-story RC building of Hakodate University collpased.[7] In Aomori Prefecture, there was damage to railroads and highways in more than 200 places caused by collapses of artificial embankments. In Hachinohe, there was damage to buildings, water pipes, and gas pipes. The 3-story building of Hachinohe Technical College suffered severe damage.[8] The communication between Honshu and Hokkaido was cut off.[9]

Tsunami

A tsunami was triggered by the earthquake,[10] with a maximum height of about 6 m.[11] A tsunami of 11 cm was recorded in Tahiti.[12] In Japan, the tsunami caused flooding and damage to the aquaculture.[10]

References

  1. ↑ 1.0 1.1 1.2 1.3 Engdahl, E. R.; Vallaseñor, A. (2002). "Global seismicity: 1900-1999". International Handbook of Earthquake & Engineering Seismology. Part A, Volume 81A (First ed.). Academic Press. p. 681. ISBN 978-0124406520. 
  2. ↑ 2.0 2.1 "Focal Mechanism of the Tokachi-Oki Earthquake of May 16, 1968: Contortion of the Lithosphere at a Junction of Two Trenches" by H. Kanamori
  3. ↑ http://www.hiroi.iii.u-tokyo.ac.jp/index-genzai_no_sigoto-tunami_joho-archives.pdf
  4. ↑ http://www.aces.org.au/ACES-2002-workshop/PDF/page333-340.pdf
  5. ↑ "Space-time distribution of interplate moment release including slow earthquakes and the seismo-geodetic coupling in the Sanriku-oki region along the Japan trench" by I. Kawasaki, Y. Asai, and Y. Tamura
  6. ↑ http://earthquake.usgs.gov/earthquakes/world/historical_country.php
  7. ↑ http://www.iitk.ac.in/nicee/wcee/article/1321.pdf
  8. ↑ "Geomorphological Accidents Caused by the Tokachi-oki Earthquake" by K. Nishimura, S. Segawa, H. Mizuno, H. Hotta, O. Miura, T. Tamura, and T. Akagiri
  9. ↑ http://danso.env.nagoya-u.ac.jp/jsafr/documents/AFR028_095_106.pdf
  10. ↑ 10.0 10.1 http://www.bousai.pref.aomori.jp/jisinsouran/tokachi/1_jisin_target.htm
  11. ↑ http://www.jishin.go.jp/main/chousa/09mar_sanriku/sanriku_boso_2_hyoka.pdf
  12. ↑ http://ioc3.unesco.org/itic/files.php?action=dlfile&fid=202&PHPSESSID=48e5d48744083035c312f673159c7a90
Japan Trench megathrust earthquakes
Notable Japan Trench megathrust quakes
Plate tectonics
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