1983 Sea of Japan earthquake

What Happened

On 26 May 1983, at 11:59:57 local time — three seconds before noon — a magnitude 7.8 earthquake struck the Sea of Japan. The epicentre lay at 40.462°N, 139.102°E, roughly 100 kilometres west of the coast of Noshiro in Akita Prefecture, beneath the water rather than under land. The shaking itself caused relatively little destruction, but the displacement of the seafloor generated a tsunami that reached the Japanese coast within minutes.

The waves exceeded 10 metres in some areas. They struck communities along the coasts of Aomori and Akita Prefectures and along the east coast of the Noto Peninsula, and television cameras captured the tsunami hitting the fishing harbour of Wajima on the Noto Peninsula, broadcasting the images nationwide. The tsunami also reached Okushiri Island, off the coast of Hokkaido.

Of the 104 fatalities, all but four were killed by the tsunami rather than by the earthquake. Three of the dead were on the east coast of South Korea, where the waves crossed the Sea of Japan.

Background

The earthquake occurred during the Shōwa period (昭和, 1926–1989), in the 58th year of the era — the year the Japanese calendar counts as Shōwa 58. Japan sits at the junction of four tectonic plates, and the Sea of Japan coast, unlike the Pacific coast facing the Tōhoku region, is not the country's most familiar earthquake zone. The 1983 event was centred in the Sea of Japan itself, west of the Akita coastline, at a location where the seabed is shallow enough for a large vertical displacement of the ocean floor to push a substantial volume of water toward the shore.

The timing mattered as much as the location. The earthquake struck at 11:59:57, just before noon, when fishing communities along the coast were active and people were near the water. The interval between the shaking and the arrival of the largest waves was short, and the affected stretch of coast — Akita, Aomori, and the Noto Peninsula — is lined with small harbours and settlements built close to the sea.

Why It Mattered

The 1983 earthquake demonstrated with terrible clarity that a tsunami, not the earthquake itself, is the primary killer in a Sea of Japan event. All but four of the 104 deaths were caused by the waves. That ratio — the earthquake as a warning, the tsunami as the weapon — shaped how coastal communities and the Japanese government thought about disaster preparedness on the Japan Sea side of the country.

The television footage from Wajima was significant in its own right. Images of the tsunami striking a working fishing harbour were broadcast on TV, bringing the event into homes across Japan and making the mechanics of a tsunami visible to a mass audience. The waves that reached Okushiri Island in 1983 foreshadowed a far deadlier tsunami that struck the same island ten years later, in 1993.

The event also crossed national borders. Three people died on the east coast of South Korea, a reminder that a tsunami generated in the Sea of Japan does not respect the distance between Japan and the Korean peninsula.

The Name in Japanese

The Japanese name of the earthquake is 日本海中部地震, read in kana as にほんかいちゅうぶじしん and romanised as Nihonkai Chūbu Jishin. Breaking it down:

日 — read here as に (ni). The kanji means "sun" or "day". It is one of the most common characters in Japanese and appears in 日本, the name for Japan.

本 — read here as ほん (hon). The kanji means "origin", "book", or "main". Combined with 日, it forms 日本 (Nihon), literally "origin of the sun" — the source of the English word "Japan".

海 — read here as かい (kai). The kanji means "sea" or "ocean". Together, 日本海 (Nihonkai) is the Sea of Japan.

中 — read here as ちゅう (chū). The kanji means "middle", "centre", or "inside". It appears in many compounds referring to a central part of something.

部 — read here as ぶ (bu). The kanji means "part", "section", or "department". Combined with 中, it forms 中部 (chūbu), meaning "central part" — the same word used in the name of the Chūbu region of central Honshu.

地 — read here as じ (ji). The kanji means "ground", "earth", or "land".

震 — read here as しん (shin). The kanji means "quake" or "shake". Together, 地震 (jishin) is the standard Japanese word for "earthquake".

So the full name parses as 日本海 (Sea of Japan) + 中部 (central part) + 地震 (earthquake): the earthquake of the central part of the Sea of Japan. The name is a precise geographic label, and it is worth noting that the same 中部 element appears in the names of other Japanese earthquakes and regions, so recognising it pays off well beyond this one event.

Key Figures

• Date and time: 26 May 1983, 11:59:57 local time (02:59:57 UTC).
• Magnitude: 7.8 on the moment magnitude scale.
• Epicentre: 40.462°N, 139.102°E, in the Sea of Japan, about 100 km west of Noshiro, Akita Prefecture.
• Fatalities: 104 in total; all but four were caused by the tsunami.
• Fatalities in South Korea: 3, along the east coast.
• Maximum tsunami height: over 10 metres (33 ft) in some areas.
• Era: Shōwa 58 (1983), during the Shōwa period (1926–1989).
• Places struck by the tsunami: the coasts of Aomori and Akita Prefectures, the east coast of the Noto Peninsula, and Okushiri Island.