EARTHQUAKEM4.2

M4.2 earthquake in the Rat Islands, Aleutian Islands, Alaska

Map: the earthquake in the Rat Islands, Aleutian Islands, Alaska, with plate boundaries

A magnitude 4.2 earthquake struck in the Rat Islands, Aleutian Islands, Alaska on Monday, October 19, 2026 at 16:27 UTC, at a depth of 32 mi (52 km), according to the U.S. Geological Survey. Shallow quakes like this one shake the surface hardest. The epicenter was about 320 mi (516 km) west of Atka, Alaska.

MagnitudeM4.2
Depth32 mi (52 km)
Time (UTC)Oct 19 16:27
Location51.52°N 178.37°E
Nearest townAtka · 516 km
Energy30 tons TNT
Aftershocks M2.5+1
Tsunami flagNo
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Why here?

This earthquake struck about 68 mi (109 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.

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 4.2 released roughly the energy of 30 tons of TNT. The strongest earthquake ever recorded, magnitude 9.5 in Chile in 1960, released about 89,000,000 times more than this one.

Aftershocks

In the first 7 days after it, USGS recorded 1 smaller earthquake of magnitude 2.5 or more within 62 mi (100 km). It was a magnitude 2.5 on October 21 at 00:13 UTC.

Earthquake history here

Before this earthquake, USGS had recorded 191 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 19, 2026 or earthquakes by day.

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