1968 Tokachi earthquake

{{Infobox earthquake

| title = 1968 Tokachi earthquake

| timestamp = 1968-05-16 00:49:02

| isc-event = 821946

| anss-url = iscgem821946

| local-date = {{Start date|1968|05|16}}

| local-time = 09:49:02

| map2 = {{Location map | Japan

| label =

| lat = 40.90

| long = 143.35

| mark = Bullseye1.png

| marksize = 40

| position = top

| width = 250

| float = right

| caption =

| relief = yes

}}

| magnitude = 8.3 {{M|w|link=y}}

| depth = {{convert|26|km|abbr=on}}

| location = {{coord|40.90|N|143.35|E}}

| type = Oblique-slip

| countries affected = Japan

| tsunami = {{convert|6|m|abbr=on}}

| aftershocks = 7.9 {{M|w|link=y|src=ISC}} May 16 at 20:39

| intensity = {{MMI|6}}{{citation|title=Significant Earthquake Database|url=https://www.ngdc.noaa.gov/hazel/view/hazards/earthquake/event-more-info/4438|author=National Geophysical Data Center / World Data Service (NGDC/WDS)|publisher=National Geophysical Data Center, NOAA|doi=10.7289/V5TD9V7K|year=1972}}

{{JMA|5-}}

| casualties = 47–52 killed
281–330 injured

}}

The 1968 Tokachi earthquake (1968年十勝沖地震 Sen-kyūhyaku-rokujūhachi-nen Tokachi-oki Jishin) occurred on May 16 at 0:49 UTC (09:49 local time) in the area offshore of Aomori and Hokkaido. The magnitude of this earthquake was put at {{M|w|link=y}} 8.3. The intensity of the earthquake reached shindo 5 in Aomori, Aomori and Hakodate, Hokkaido.{{Cite web |url=http://www.hiroi.iii.u-tokyo.ac.jp/index-genzai_no_sigoto-tunami_joho-archives.pdf |title=Tsunami forecast Archives |access-date=2012-04-09 |archive-date=2013-10-29 |archive-url=https://web.archive.org/web/20131029224634/http://www.hiroi.iii.u-tokyo.ac.jp/index-genzai_no_sigoto-tunami_joho-archives.pdf |url-status=dead }}

Geology

This earthquake was located near the junction of the Kuril Trench and the Japan Trench. It was an interplate earthquake.{{cite web|url=http://www.aces.org.au/ACES-2002-workshop/PDF/page333-340.pdf|date=13 November 2003|title=Crustal Deformation Model in Northeast Japan|author1=Hisashi Suito|author2=Mikio Iizuka|author3=Kazuro Hirahara|accessdate=2014-09-12|archive-url=https://web.archive.org/web/20150301060337/http://aces.org.au/ACES-2002-workshop/PDF/page333-340.pdf|archive-date=2015-03-01|url-status=dead}} The focal mechanism of this earthquake showed movement on a thrust fault with a considerable slip-strike component.{{citation|title=Focal Mechanism of the Tokachi-Oki Earthquake of May 16, 1968: Contortion of the Lithosphere at a Junction of Two Trenches|first=H.|last=Kanamori|authorlink=Hiroo Kanamori|year=1971|journal=Tectonophysics|volume=12|issue=1|pages= 1–13|doi=10.1016/0040-1951(71)90063-1|bibcode=1971Tectp..12....1K}} The sum of interplate seismic moment release by seismic and aseismic faulting in this earthquake was about 28×10²⁰ N m. The 1960s was noted as one of the peak periods of interplate seismic moment release in the offshore Sanriku region."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

Damage

Heavy rain occurred due to a low pressure system in the days leading up to the earthquake and aggravated the damage. In Hokkaido, building damage was reported. A four-story RC building of Hakodate University collapsed.{{cite web|url=http://www.iitk.ac.in/nicee/wcee/article/1321.pdf|date=16 December 1999|title=DAMAGES TO BEAM-TO-COLUMN JOINT PANELS OF R/C BUILDINGS CAUSED BY THE 1995 HYOGO-KEN NANBU EARTHQUAKE AND THE ANALYSIS|author =Masaya HIROSAWA|author2 =Tomoaki AKIYAMA|author3 =Tatsuya KONDO|author4 =Jiandong ZHOU|name-list-style =amp|accessdate=2014-09-12}} 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 three-story building of Hachinohe Technical College suffered severe damage."Geomorphological Accidents Caused by the Tokachi-oki Earthquake" by K. Nishimura, S. Segawa, H. Mizuno, H. Hotta, O. Miura, T. Tamura, and T. Akagiri The communication between Honshu and Hokkaido was cut off.{{cite web|url=http://danso.env.nagoya-u.ac.jp/jsafr/documents/AFR028_095_106.pdf|date=19 September 2008|title=Earthquake and lifeline damage|author=Junji Kiyono|accessdate=2014-09-12|archive-url=https://web.archive.org/web/20130612072739/http://danso.env.nagoya-u.ac.jp/jsafr/documents/AFR028_095_106.pdf|archive-date=2013-06-12|url-status=dead}}

Tsunami

A tsunami was triggered by the earthquake,{{cite web|url=http://www.bousai.pref.aomori.jp/jisinsouran/tokachi/1_jisin_target.htm|title=十勝沖地震地震の概要|publisher=Bousai.pref.aomori.jp|accessdate=2014-09-12|archive-url=https://web.archive.org/web/20150923194042/http://www.bousai.pref.aomori.jp/jisinsouran/tokachi/1_jisin_target.htm|archive-date=2015-09-23|url-status=dead}} with a maximum height of about {{convert|6|m|abbr=on}}.{{cite web|url=http://www.jishin.go.jp/main/chousa/09mar_sanriku/sanriku_boso_2_hyoka.pdf|date=22 August 2008|title=三陸沖から房総沖にかけての地震活動の長期評価の一部改訂について（平成21年3月9日公表）|author =地震調査研究推進本部地震調査委員会|accessdate=2014-09-12}} An {{convert|11|cm|in|sp=us|adj=mid}} high tsunami was recorded in Tahiti.[http://ioc3.unesco.org/itic/files.php?action=dlfile&fid=202&PHPSESSID=48e5d48744083035c312f673159c7a90] {{dead link|date=November 2014}} In Japan, the tsunami caused flooding and damage to aquaculture.

References

{{Reflist|refs=

{{citation|title=PAGER-CAT Earthquake Catalog|url=https://earthquake.usgs.gov/static/lfs/data/pager/catalogs/|date=September 4, 2009|publisher=United States Geological Survey|series=Version 2008_06.1}}

}}

External links

{{EQ-isc-link|821946}}

Tokachi

Category:1968 in Japan

Category:1960s tsunamis

Category:May 1968 in Asia

Category:Earthquakes of the Showa era

Category:Megathrust earthquakes in Japan

Category:1968 disasters in Japan