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 , officially Aomori City (, ), is the capital Cities of Japan, city of Aomori Prefecture, in the Tōhoku region of Japan. , the city had an estimated population of 264,945 in 136,781 households, and a population density of 321 people per squa ...

and

Hokkaido is the list of islands of Japan by area, second-largest island of Japan and comprises the largest and northernmost prefectures of Japan, prefecture, making up its own list of regions of Japan, region. The Tsugaru Strait separates Hokkaidō fr ...

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

, Aomori and

Hakodate is a Cities of Japan, city and seaports of Japan, port located in Oshima Subprefecture, Hokkaido, Japan. It is the capital city of Oshima Subprefecture. As of January 31, 2024, the city had an estimated population of 239,813 with 138,807 househol ...

, Hokkaido.

Geology

This earthquake was located near the junction of the Kuril Trench 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 The focal mechanism of an earthquake describes the Fault (geology)#Slip.2C heave.2C throw, deformation in the Hypocenter, source region that generates the seismic waves. In the case of a Fault (geology), fault-related event, it refers to the ori ...

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. I ...

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 213,453 in 110,121 households, and a population density of . As of October 2020, Hachinohe is Aomori Prefecture's second largest city by population. The c ...

, 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 known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the list of islands by area, seventh-largest island in the world, and the list of islands by ...

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 language, Tahitian , ; ) is the largest island of the Windward Islands (Society Islands), Windward group of the Society Islands in French Polynesia, an overseas collectivity of France. It is located in the central part of t ...

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

References

External links

* {{JapanTrenchMegathrust Tokachi 1968 in Japan 1960s tsunamis May 1968 in Asia Earthquakes of the Showa era Megathrust earthquakes in Japan 1968 disasters in Japan

Geology

Damage

Tsunami

See also

References

Further reading

External links