EARTHQUAKEM5.5

M5.5 earthquake near Neiafu, Tonga

Map: the earthquake near Neiafu, Tonga, with plate boundaries

A magnitude 5.5 earthquake struck 122 km (76 mi) west of Neiafu, Tonga on Monday, October 12, 2026 at 04:38 UTC, at a depth of 195 km (121 mi), according to the U.S. Geological Survey. At this intermediate depth, shaking spreads out before it reaches the surface.

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

1 person reported feeling it to USGS “Did You Feel It?”.

MagnitudeM5.5
Depth195 km (121 mi)
Time (UTC)Oct 12 04:38
Location18.72°S 175.15°W
Nearest townNeiafu · 122 km
Energy3 kilotons TNT
Aftershocks M2.5+1
Tsunami flagNo
PAGER alertGREEN
Felt reports1
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Why here?

This earthquake struck right along the boundary between the Tonga and Niuafo'ou 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 195 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.

What kind of fault?

USGS’s analysis of the seismic waves shows it was an oblique earthquake: the fault slipped partly sideways and partly as one block dropped down as the crust stretched.

Shaking and impact

The strongest shaking USGS estimates was intensity 3 on the Modified Mercalli scale: weak. USGS’s PAGER system estimates it most likely caused no deaths (90 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 14 days after it, USGS recorded 1 smaller earthquake of magnitude 2.5 or more within 100 km (62 mi). It was a magnitude 4.5 on October 16 at 15:06 UTC.

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 208 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 12, 2026 or earthquakes by day.

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