EARTHQUAKEM4.5

M4.5 earthquake in the Balleny Islands region

Map: the earthquake in the Balleny Islands region, with plate boundaries

A magnitude 4.5 earthquake struck in the Balleny Islands region on Friday, October 23, 2026 at 08:17 UTC, at a depth of 10 km (6 mi), according to the U.S. Geological Survey. Shallow quakes like this one shake the surface hardest. It struck far from land: no town on our map lies within 600 km (373 mi).

MagnitudeM4.5
Depth10 km (6 mi)
Time (UTC)Oct 23 08:17
Location61.67°S 154.08°E
Energy85 tons TNT
Aftershocks M2.5+0
Tsunami flagNo
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Why here?

This earthquake struck about 41 km (25 mi) from the boundary between the Australian and Antarctic 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 4.5 released roughly the energy of 85 tons of TNT. That is about 5.6 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 32,000,000 times more than this one.

Aftershocks

In the first 3 days after it, USGS recorded no smaller earthquakes of magnitude 2.5 or more within 100 km (62 mi).

Outside the United States, USGS mainly lists quakes of about magnitude 4 and up, so smaller aftershocks there are undercounted.

Earthquake history here

Before this earthquake, USGS had recorded 48 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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