Date May 16, 1968 Magnitude 8.3 Mw Type Oblique-slip | Origin time 0:49 UTC Depth 26 km (16 mi) Areas affected Japan | |
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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 Aomori and Hokkaido. The magnitude of this earthquake was put at Mw 8.3. The intensity of the earthquake reached shindo 5 in Aomori, Aomori and Hakodate, Hokkaido.
Contents
Geology
This earthquake was located near the junction of the Kuril Trench and the Japan Trench. It is an interplate earthquake. The focal mechanism of this earthquake shows movement on a thrust fault with a considerable slip-strike component. The sum of interplate seismic moment release by seismic and aseismic faulting in this earthquake is 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 days before the earthquake and aggravated the damage. In Hokkaido, building damage was reported. A 4-story RC building of Hakodate University collpased. 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. The communication between Honshu and Hokkaido was cut off.
Tsunami
A tsunami was triggered by the earthquake, with a maximum height of about 6 m (20 ft). A tsunami of 11 cm was recorded in Tahiti. In Japan, the tsunami caused flooding and damage to the aquaculture.