EARTHQUAKEM4.6

M4.6 earthquake near Nikolski, Alaska

Map: the earthquake near Nikolski, Alaska, with plate boundaries

A magnitude 4.6 earthquake struck 62 mi (100 km) north-northwest of Nikolski, Alaska on Friday, October 23, 2026 at 23:08 UTC, at a depth of 143 mi (230 km), according to the U.S. Geological Survey. At this intermediate depth, shaking spreads out before it reaches the surface.

MagnitudeM4.6
Depth143 mi (230 km)
Time (UTC)Oct 23 23:08
Location53.78°N 169.41°W
Nearest townNikolski · 100 km
Energy120 tons TNT
Aftershocks M2.5+0
Tsunami flagNo
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Why here?

This earthquake struck about 148 mi (238 km) from the boundary between the North American and Pacific plates. Most earthquakes happen along plate boundaries like this one, where the pieces of Earth’s outer shell collide, pull apart or grind past each other. Stress builds up over years until the rock suddenly slips. At 230 km down, it most likely broke inside a plate that is sinking into the mantle beneath its neighbor, in what geologists call a subduction zone.

The red lines on the map are plate boundaries.

How strong was it?

Magnitude is logarithmic: each whole step releases about 32 times more energy. This magnitude 4.6 released roughly the energy of 120 tons of TNT. That is about 7.9 times the energy of a magnitude 4.0, a quake people nearby feel but that rarely causes damage. The strongest earthquake ever recorded, magnitude 9.5 in Chile in 1960, released about 22,000,000 times more than this one.

Aftershocks

In the first 2 days after it, USGS recorded no smaller earthquakes of magnitude 2.5 or more within 62 mi (100 km).

Earthquake history here

Before this earthquake, USGS had recorded 129 earthquakes of magnitude 6 or larger within 300 km (186 mi) since 1900. The strongest:

Official details, updates and the shaking map: USGS event page.

See every earthquake on October 23, 2026 or earthquakes by day.

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