M6.3 earthquake 84 km SSW of Nikolski, Alaska

Thursday, September 3, 2026, 11:17:24 UTC · 52.258°N, 169.409°W

A magnitude 6.3 earthquake struck 84 km SSW of Nikolski, Alaska on Thursday, September 3, 2026, 11:17:24 UTC, at a depth of 35.0 km (shallow). USGS received 3 “Did You Feel It?” reports, with a maximum reported intensity of V (moderate). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M6.6 on January 11, 2022.

Tsunami flagUSGS sets this flag for large events in oceanic regions so tsunami warning centers review them. It does not by itself mean a tsunami occurred. Check tsunami.gov and local authorities for official messages.

Magnitude: 6.3; Strong · mww
Depth: 35 km; Shallow
Felt reports: 3; Max intensity V
Est. shaking: IV; Light (ShakeMap)
PAGER alert: Green; Impact estimate
Tsunami: Flag; Check tsunami.gov

Outlined circle: this earthquakeDashed circle: 100 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

43 kilotons of TNT

That is about 3 times the Hiroshima bomb. It released about 89 times the energy of a magnitude 5.0.

Tectonic setting

64 km

from the nearest mapped plate boundary, between the North American and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: shallow

35 km

Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.

Did You Feel It?

Where it was felt

Reports sent by people to USGS, grouped by place (most reports first). Intensity uses the Modified Mercalli scale (I–X): what people felt, not the magnitude.

Place	Intensity	Reports	Distance
99638<br>0.320	V · Moderate	2	116 km
99615<br>0.330	I · Not felt	1	1186 km

I felt it — report to USGS ↗

USGS PAGER estimate

Who was exposed to shaking

Modelled from the ShakeMap and population data. Alert level green: low likelihood of casualties and damage.

III · Weak shaking: 4,300 people

Estimated shaking in nearby towns

UnalaskaPopulation 4,300III · Weak

After the main event

Aftershocks within 100 km

USGS lists 220 M2.5+ earthquakes within 100 km since this event; the largest was M5.4 on September 3, 2026. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 753 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 13 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:

1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 143 km away
Limited damage (under $1M)tsunami
1965M6.5
Aleutian Islands: Fox Islands
2 Jul 1965 · 152 km away
Limited damage (under $1M)tsunami
1917M7.9
Alaska Peninsula
31 May 1917 · 282 km away · intensity V
1902M7.8
Aleutian Islands: Fox Islands
1 Jan 1902 · 131 km away
1907M7.8
Aleutian Islands
2 Sep 1907 · 43 km away
1929M7.8
Aleutian Islands: Fox Islands
7 Mar 1929 · 146 km away · intensity V
tsunami

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers