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 is the capital city of Aomori Prefecture, in the Tōhoku region of Japan. , the city had an estimated population of 278,964 in 136,457 households, and a population density of 340 people per square kilometer spread over the city's total area of ...

and

Hokkaido is Japan's second largest island and comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu; the two islands are connected by the undersea railway Seikan Tunnel. The la ...

. The magnitude of this earthquake was put at 8.3. The intensity of the earthquake reached shindo 5 in

, Aomori and

Hakodate is a city and port located in Oshima Subprefecture, Hokkaido, Japan. It is the capital city of Oshima Subprefecture. As of July 31, 2011, the city has an estimated population of 279,851 with 143,221 households, and a population density of 412.8 ...

, Hokkaido.

Geology

This earthquake was located near the junction of the

Kuril Trench The Kuril Islands or Kurile Islands (; rus, Кури́льские острова́, r=Kuril'skiye ostrova, p=kʊˈrʲilʲskʲɪjə ɐstrɐˈva; Japanese: or ) are a volcanic archipelago currently administered as part of Sakhalin Oblast in the ...

and the

Japan Trench The Japan Trench is an oceanic trench part of the Pacific Ring of Fire off northeast Japan. It extends from the Kuril Islands to the northern end of the Izu Islands, and is at its deepest. It links the Kuril–Kamchatka Trench to the north and ...

. It was an interplate earthquake. The focal mechanism of this earthquake showed movement on a

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...

with a considerable slip-strike component. 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.

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. In Aomori Prefecture, there was damage to railroads and highways in more than 200 places caused by collapses of artificial embankments. In

Hachinohe is a city located in Aomori Prefecture, Japan. , the city had an estimated population of 221,459, and a population density of 725 persons per km2 in 96,092 households, making it Aomori Prefecture's second largest city by population. The city ...

, there was damage to buildings, water pipes, and gas pipes. The three-story building of Hachinohe Technical College suffered severe damage. The communication between

Honshu , historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island separ ...

and Hokkaido was cut off.

Tsunami

A tsunami was triggered by the earthquake, with a maximum height of about . An high tsunami was recorded in

Tahiti Tahiti (; Tahitian ; ; previously also known as Otaheite) is the largest island of the Windward group of the Society Islands in French Polynesia. It is located in the central part of the Pacific Ocean and the nearest major landmass is Austr ...

.
In Japan, the tsunami caused flooding and damage to aquaculture.

References

External links

* {{JapanTrenchMegathrust Tokachi 1968 in Japan 1968 tsunamis May 1968 events in Asia Earthquakes of the Showa period Megathrust earthquakes in Japan 1968 disasters in Japan

Geology

Damage

Tsunami

See also

References

Further reading

External links