Major M7.4 earthquake hits near east coast of Honshu, Japan, tsunami waves observed along Tohoku coast
A major earthquake registered by the USGS as M7.4 struck near the east coast of Honshu, Japan, at 07:53 UTC (16:53 local time) on April 20, 2026. The agency is reporting a depth of 35 km (21.7 miles). JMA and EMSC are reporting M7.4 at a depth of 10 km (6 miles). According to the Pacific Tsunami Warning Center (PTWC), hazardous tsunami waves are possible within 300 km (186 miles) of the epicenter. At least 4 people were killed and more than 225 injured.
Epicenter of M7.4 earthquake near east coast of Honshu, Japan on April 20, 2026. Credit: TW/SAM, Google
The epicenter was located 100 km (62 miles) ENE of Miyako (population 51 150), 108 km (67 miles) ENE of Yamada (population 15 195), and 112 km (69 miles) ESE of Kuji (population 34 418), Japan.
333 000 people are estimated to have felt strong shaking, 3 830 000 moderate, and 5 205 000 light.
According to the Pacific Tsunami Warning Center (PTWC), hazardous tsunami waves are possible within 300 km (186 miles) of the epicenter.
Estimated times of arrival for the initial tsunami wave indicate that impacts would begin shortly after the earthquake. The first wave was estimated to reach Hachinohe, Japan (40.5°N 141.5°E) at 08:34 UTC. However, actual arrival times may vary, and the first wave may not be the largest. Tsunamis consist of a series of waves, with intervals between them ranging from 5 minutes to 1 hour.
A tsunami is not a single wave but a sequence of waves that can continue for many hours or longer after the initial arrival. The duration and strength of the hazard can vary significantly, meaning coastal areas may remain at risk well beyond the first observed wave.
Long-period ground motion was widely observed following the earthquake, according to the Japan Meteorological Agency (JMA). Intensity 3 long-period motion was recorded in northern Miyagi Prefecture and southern inland areas of Akita Prefecture.
Intensity 2 long-period motion was observed across a broader region, including parts of Aomori, Iwate, Miyagi, Akita, Yamagata, and Niigata prefectures. The levels suggest noticeable and prolonged shaking, particularly affecting high-rise buildings and large structures.
Weaker long-period motion (intensity 1) extended over a much larger area, reaching parts of Hokkaido, Fukushima, Ibaraki, Saitama, Chiba, Tokyo, Kanagawa, Yamanashi, Nagano, and Shizuoka.
The USGS issued a Green alert for shaking-related fatalities and economic losses. There is a low likelihood of casualties and damage.
Overall, the population in this region resides in structures that are resistant to earthquake shaking, though vulnerable structures exist. The predominant vulnerable building types are heavy wood frame and reinforced/confined masonry construction.
Recent earthquakes in this area have caused secondary hazards such as tsunamis, landslides and fires that might have contributed to losses.
Updates
08:51 UTC, April 20
A tsunami measuring 80 cm (31.5 inches) was observed at Kuji Port in Iwate Prefecture at 08:34 UTC (17:34 LT), while a tsunami measuring 40 cm (15.7 inches) was observed at Miyako Port, also in Iwate Prefecture, at 08:22 UTC (17:22 LT).
JMA also confirmed tsunami activity off the coast of Miyagi Prefecture, as per NHK.
A tsunami up to 1 m (3.3 feet) is expected to reach the coast of Miyagi Prefecture. Authorities urged immediate evacuation.
The agency warned that tsunami waves arrive in a series and that later waves may be higher than the first. It added that, in some areas, tsunami heights may already exceed those recorded at tide gauge stations.
19:45 UTC, April 20
At least 4 people were killed and more than 225 injured. The deaths included a man in his 60s from Soma who died after falling from the second floor of his house while trying to evacuate and a 70-year-old man who suffered a heart attack.
According to Tokyo Electric Power Company (TEPCO), around 2.2 million homes across 14 prefectures, including Tokyo, experienced power outages.
Damage included shattered windows and structural issues in weaker buildings.
Bullet train services in Aomori Prefecture were suspended.
Thousands of people from coastal towns including Otsuchi and Kamaishi evacuated to higher ground. The JMA maintained tsunami advisories for affected areas through the morning hours as the threat gradually subsided.
JMA said there was a 1% chance for a mega-quake for Pacific coastal region, compared to a 0.1% chance during normal times, in the next week or so following.
Estimated population exposure to earthquake shaking
Selected cities exposed
Regional seismicity
References:
1 M7.4 earthquake near east coast of Honshu, Japan – USGS – April 20, 2026
2 M7.4 earthquake near east coast of Honshu, Japan – EMSC – April 20, 2026
3 M7.4 earthquake near east coast of Honshu, Japan – JMA – April 20, 2026
4 Tsunami Threat Message for M7.4 earthquake near east coast of Honshu, Japan – PTWC – April 20, 2026
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This earthquake is the result of the strong solar flare, two days ago.
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