EARTHQUAKEM4.8

M4.8 earthquake in the south of the Fiji Islands

Map: the earthquake in the south of the Fiji Islands, with plate boundaries

A magnitude 4.8 earthquake struck in the south of the Fiji Islands on Tuesday, October 20, 2026 at 16:29 UTC, at a depth of 110 km (68 mi), according to the U.S. Geological Survey. At this intermediate depth, shaking spreads out before it reaches the surface. The epicenter was about 385 km (239 mi) southwest of Nukualofa, Tonga.

MagnitudeM4.8
Depth110 km (68 mi)
Time (UTC)Oct 20 16:29
Location24.18°S 177.01°W
Nearest townNukualofa · 385 km
Energy239 tons TNT
Aftershocks M2.5+0
Tsunami flagNo
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Why here?

This earthquake struck about 42 km (26 mi) from the boundary between the Australian and Tonga 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 110 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 4.8 released roughly the energy of 239 tons of TNT. That is about 16 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 11,000,000 times more than this one.

Aftershocks

In the first 5 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 123 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 20, 2026 or earthquakes by day.

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