Shallow M5.4 AFTERSHOCK hit in the North Pacific Ocean 195km from Hachinohe (Japan) on Tuesday Afternoon.

Written by Earthquakelist.org on April 21st, 2026.

In the North Pacific Ocean 195 kilometer from Hachinohe, Japan, a shallow and significant M5.4 aftershock occurred in the afternoon of Tuesday April 21st, 2026. Shaking may have been felt by a total of 710 thousand people.

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Earthquake Summary

This earthquake hit under water in the North Pacific Ocean, 176 kilometers (110 mi) off the coast of Japan, 195 kilometer east of Hachinohe in Aomori. The center of this earthquake had a very shallow depth of 10 km. Shallow earthquakes usually have a larger impact than earthquakes deep in the earth.

Date and Time:	Apr 21, 2026 14:29 (Tokyo Time) - Apr 21, 2026 05:29 Universal Time.
Location:	195 km east of Hachinohe, Aomori, Japan. Coordinates 39°50'53"N 143°37'38"E.
Map:	Map of area around epicenter. Click to open in Google Maps.
Magnitude:	MAG 5.4 Detected by 17 stations. Maximum Error Range ±0.075 .
Depth:	10 km (6 mi) A very shallow depth.
Max. Intensity:	IV Light On the Modified Mercalli Scale.
Tsunami Risk:	Low tsunami risk Earthquakes under MAG-6.5 do not usually cause tsunami's. Always stay cautious - More info here.

Minimal impact predicted

Based on scientific estimates by the US Geographic Survey (USGS), the risk of high fatalities for this earthquake is classified at level GREEN (low). They expect an 90% likelyhood of between 0 and 1 fatalities.

The USGS classifies the economic impact of this earthquake at level GREEN (low). They expect an 90% likelyhood of between 0 and 1 million US Dollars in economic damage and impact.

Roughly 710 thousand people exposed to shaking

This earthquake may have been felt by around 710 thousand people. That is the expected population size of the area exposed to a level of shaking of II or higher on the Modified Mercalli scale according to the USGS.

Weak shaking and probably no damage may have been experienced by an estimated 503,600 people. At III, it is the highest MMI level this earthquake has caused. All exposure to shaking was within the borders of Japan .

Nearby towns and cities

This earthquake may have been felt in Japan . The closest significant population center near the earthquake is Miyako in Iwate, Japan. Miyako is located 146 kilometer (91 mi) east of the epicenter. Miyako experienced an earthquake intensity (MMI Scale) of roughly III. That level implies weak shaking and probably no damage.

Multiple large cities are in proximity of today's earthquake. Sendai is located 296 km to the southwest (intensity unknown, possibly low). Morioka is located 212 km to the west (intensity unknown, possibly low). Hachinohe is located 195 km to the west and experienced an intensity of III (weak shaking, probably no damage).

A complete list of nearby places is included below. Estimated intensity data (MMI) sourced from a shake-map published by the US Geographic Survey is shown where available (cities without data probably experienced little impact).

Overview of nearby places

Earthquake Intensity Map

The graph below overlays a map of the region around the epicenter with earthquake intensity data provided by the US Geographic Survey. The highest intensity level detected for this earthquake is III.

I Not felt

II Weak

III Weak

IV Light

V Moderate

VI Strong

VII Very Strong

VIII Severe

IX Violent

X Extreme

This is likely an aftershock

This earthquake is likely an aftershock of the MAG-7.4 earthquake that struck 22 hrs earlier. That main earthquake hit 51 km (32 mi) west of the epicenter of this MAG-5.4 aftershock.

Overview of foreshocks and aftershocks

More earthquakes coming?

Aftershocks are usually at least 1 order of magnitude less strong than main shocks. The more time passes, the smaller the chance and likely strength of any potential aftershocks.

It's always adviced to be cautious of the risk of a larger shock following any significant earthquake, however this risk is fairly small. There is a roughly 94 percent change that no larger main shock will follow in the days following this earthquake.

Earthquakes like this happen often in the region

Earthquakes of this strength are very common in the region. In total, 87 earthquakes with a magnitude of 5.4 or higher have been registered within 300km (186 mi) of this epicenter in the past 10 years. This comes down to an average of once every month.

Low tsunami risk

Based on early data it appears this earthquake was not strong enough (lower than MAG-6.5) to be likely to cause destructive tsunami's. However this earthquake appeared to have hit at a shallow depth under sea, so stay cautious and monitor advice from local authorities.

Tsunami Risk Factors

Sources

Last updated 21/04/26 10:08 (). This article contains currently available information about the earthquake and is automatically composed. We continue to update this article up to a few days after the earthquake occurred.

1. US Geographic Society (USGS): Earthquake us6000srs6
2. European-Mediterranean Seismological Centre (EMSC): Earthquake 20260421_0000098
3. Geonames.org: World Cities Database
4. Google Maps: Static API
5. Earthquakelist.org: Historic Earthquakes Database

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