EARTHQUAKEM5.5

M5.5 earthquake in the west of Macquarie Island

Map: the earthquake in the west of Macquarie Island, with plate boundaries

A magnitude 5.5 earthquake struck in the west of Macquarie Island on Thursday, October 8, 2026 at 06:46 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).

USGS’s PAGER impact estimate is GREEN: little or no damage expected.

MagnitudeM5.5
Depth10 km (6 mi)
Time (UTC)Oct 8 06:46
Location52.57°S 140.14°E
Energy3 kilotons TNT
Aftershocks M2.5+0
Tsunami flagNo
PAGER alertGREEN
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Why here?

This earthquake struck about 84 km (52 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.

What kind of fault?

USGS’s analysis of the seismic waves shows it was a strike-slip earthquake: the two sides of the fault slid past each other sideways, like California’s San Andreas Fault.

Shaking and impact

USGS’s PAGER system estimates it most likely caused no deaths (99 percent probability). Early estimates are revised as reports come in.

How strong was it?

Magnitude is logarithmic: each whole step releases about 32 times more energy. This magnitude 5.5 released roughly the energy of 3 kilotons of TNT. That is about 178 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 1,000,000 times more than this one.

Aftershocks

In the first 18 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 42 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 8, 2026 or earthquakes by day.

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