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M1.5 Earthquake near Port Alsworth, United States — 01 September 2026

A micro earthquake of magnitude 1.5 was recorded near Port Alsworth, United States on , with an epicentre 63 km east of Port Alsworth, at a focal depth of 140.0 km. It ranked as the 3221st strongest of 7688 earthquakes recorded in the United States in the preceding 30 days.

1.5 Micro

Time (UTC): 2026-09-01 17:27:48

Time (your timezone): —

Magnitude: 1.5 (micro)

Focal depth: 140.0 km (intermediate)

Epicentre: 60.1580, -153.1750

Location: 63 km E of Port Alsworth, Alaska

Country: United States

USGS link to NOAA tsunami information: Not linked

Review status: Automatic

Source: USGS event page

How strong was this earthquake?

Micro earthquakes are almost never felt at the surface and are recorded only by seismographs.

A magnitude 1.5 earthquake radiates roughly 2.7 kg of TNT equivalent in seismic energy.

The USGS assigns this earthquake a significance score of 35, 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 07:15 local solar time at the epicentre, around dawn.

This event was deeper than 100% of the 152,594 earthquakes recorded in the United States in our catalogue and stronger than 58% of them.

Where was the epicentre?

The epicentre was located at 60.1580, -153.1750 — 63 km east of Port Alsworth. The closest other recorded event was a magnitude 2.4 earthquake 3 km southwest of here on 29 August 2026.

The nearest other settlements in our records are Aleneva (222 km south) and Alaska Peninsula National Wildlife Refuge (239 km south-southwest).

Why the 140 km depth matters

At 140 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, events this small are usually detected by instruments rather than people. 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 M1.5 it falls below the magnitude 6.5 threshold that generally applies before a submarine earthquake displaces enough water to generate a damaging tsunami; its 140 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 since this event was recorded.

30 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 4.9 event near Clam Gulch on 27 June 2026. This M1.5 event released about 125,893 times less energy than that event.

3220 earthquakes have been recorded within 100 km of this epicentre in the past year, 215 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 September 2026 worldwide record, and of earthquakes in the United States during September 2026. Browse the full monthly archive to compare periods.

Nearest recorded earthquakes to this epicentre

Other recent earthquakes in the United States

All recorded earthquakes in the United States →

Other magnitude 1 earthquakes worldwide

Questions about this earthquake

How strong was the earthquake near Port Alsworth?

It measured magnitude 1.5 — a micro earthquake. A magnitude 1.5 earthquake radiates roughly 2.7 kg of TNT equivalent in seismic energy.

How deep was the earthquake near Port Alsworth?

The focus was 140 km below the surface, which counts as intermediate.

Was the Port Alsworth earthquake felt at the surface?

At magnitude 1.5 and a focal depth of 140 km, the depth spreads the energy out, so shaking is weaker overhead but reaches further.

When did the earthquake near Port Alsworth happen?

01 September 2026 at 17:27 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 since this event was recorded.

How often do earthquakes happen near Port Alsworth?

30 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 4.9 event near Clam Gulch on 27 June 2026. This M1.5 event released about 125,893 times less energy than that event.