Earthquake.now

M4.5 Earthquake near Ajigasawa, Japan — 17 February 2026

A light earthquake of magnitude 4.5 was recorded near Ajigasawa, Japan on , with an epicentre 21 km north-northwest of Ajigasawa, at a focal depth of 160.1 km. It ranked as the 29th strongest of 49 earthquakes recorded in Japan in the preceding 30 days.

4.5 Light

Time (UTC): 2026-02-17 02:30:12

Time (your timezone): —

Magnitude: 4.5 (light)

Focal depth: 160.1 km (intermediate)

Epicentre: 40.9414, 140.0850

Location: 21 km NNW of Ajigasawa, Japan

Country: Japan

USGS link to NOAA tsunami information: Not linked

Review status: Reviewed

Source: USGS event page

How strong was this earthquake?

Light earthquakes are widely felt near the epicentre and can rattle windows, dishes and hanging objects. Damage is uncommon and usually limited to cracked plaster or fallen loose items.

A magnitude 4.5 earthquake radiates roughly 85 tons of TNT equivalent in seismic energy.

The USGS assigns this earthquake a significance score of 312, which is below the USGS threshold of more than 600 for its significant-earthquake list. The ranking combines magnitude with available Did You Feel It responses and PAGER alert level; it is not a direct measurement of damage.

What the magnitude scale actually measures →

When it happened locally

That is about 11:50 local solar time at the epicentre, during the morning.

This event was deeper than 89% of the 1,225 earthquakes recorded in Japan in our catalogue and stronger than 28% of them.

Where was the epicentre?

The epicentre was located at 40.9414, 140.0850 — 21 km north-northwest of Ajigasawa. The closest other recorded event was a magnitude 4.2 earthquake 29 km east-northeast of here on 08 August 2026.

The nearest other settlements in our records are Imabetsu (29 km east-northeast), Hirosaki (43 km south-southeast), Hiranai (74 km east) and Sai (76 km northeast).

Why the 160 km depth matters

At 160 km this was an intermediate-depth earthquake. Energy from events at this depth spreads out before it reaches the surface, which usually means weaker shaking near the epicentre than a shallow quake of the same magnitude, but shaking felt across a wider area.

This catalogue does not ingest eyewitness responses, so it cannot confirm where this earthquake was felt. Based on magnitude alone, an event this size is often felt across the surrounding area. Its intermediate depth normally reduces peak shaking near the epicentre compared with a shallow event of the same magnitude.

Read more on how focal depth changes what you feel →

What does the tsunami information flag mean?

The USGS record does not carry a link to NOAA tsunami information. That field is not an all-clear and does not state whether a tsunami occurred. In this case, a damaging tsunami would be less likely because at M4.5 it falls below the magnitude 6.5 threshold that generally applies before a submarine earthquake displaces enough water to generate a damaging tsunami; its 160 km focal depth is too great to deform the sea floor significantly; it occurred inland rather than beneath the sea floor. For an active coastal alert, use tsunami.gov or your local warning authority.

How earthquakes generate tsunamis, and what the alert levels mean →

Aftershocks and local seismic history

No further earthquakes have been recorded within about 150 km of the epicentre in the seven days after this event.

67 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 5.9 event near Otobe on 09 March 2026. This M4.5 event released about 126 times less energy than that event.

5 earthquakes have been recorded within 100 km of this epicentre in the past year, 0 of them in the past 30 days.

How long aftershock sequences last, and how large they get →

Where this event sits in the record

This earthquake is part of the February 2026 worldwide record, and of earthquakes in Japan during February 2026. Browse the full monthly archive to compare periods.

Nearest recorded earthquakes to this epicentre

Other recent earthquakes in Japan

All recorded earthquakes in Japan →

Other magnitude 4 earthquakes worldwide

All magnitude 4 earthquakes →

Questions about this earthquake

How strong was the earthquake near Ajigasawa?

It measured magnitude 4.5 — a light earthquake. A magnitude 4.5 earthquake radiates roughly 85 tons of TNT equivalent in seismic energy.

How deep was the earthquake near Ajigasawa?

The focus was 160 km below the surface, which counts as intermediate.

Was the Ajigasawa earthquake felt at the surface?

At magnitude 4.5 and a focal depth of 160 km, the depth spreads the energy out, so shaking is weaker overhead but reaches further.

When did the earthquake near Ajigasawa happen?

17 February 2026 at 02:30 UTC.

Was there a tsunami?

No. The USGS record carries no tsunami-information link for this event.

Have there been aftershocks?

No further earthquakes have been recorded within about 150 km of the epicentre in the seven days after this event.

How often do earthquakes happen near Ajigasawa?

67 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 5.9 event near Otobe on 09 March 2026. This M4.5 event released about 126 times less energy than that event.