EARTHQUAKEM6.3

M6.3 earthquake near Port-Olry, Vanuatu

Map: the earthquake near Port-Olry, Vanuatu, with plate boundaries

First reported as magnitude 6.6, the earthquake has since been revised to 6.3 by the US Geological Survey. Early estimates come within minutes from the first seismic stations; the reviewed figure takes in many more.

A magnitude 6.3 earthquake struck 197 km (122 mi) northwest of Port-Olry, Vanuatu on Tuesday, October 20, 2026 at 04:20 UTC, at a depth of 16 km (10 mi), according to the U.S. Geological Survey. Shallow quakes like this one shake the surface hardest.

USGS set its tsunami flag for this earthquake. The flag is set automatically for large earthquakes at sea and is not a warning. For official tsunami information, see tsunami.gov and your national warning center.

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

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

MagnitudeM6.3
Depth16 km (10 mi)
Time (UTC)Oct 20 04:20
Location13.99°S 165.59°E
Nearest townPort-Olry · 197 km
Energy43 kilotons TNT
Aftershocks M2.5+56
Tsunami flagSet (not a warning)
PAGER alertGREEN
Felt reports1
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Why here?

This earthquake struck about 65 km (41 mi) from the boundary between the Pacific and Australian 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 normal-fault earthquake: the crust was being stretched, and one block dropped down relative to the other.

Shaking and impact

The strongest shaking USGS estimates was intensity 4 on the Modified Mercalli scale: light. 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 6.3 released roughly the energy of 43 kilotons of TNT, about 2.8 times the Hiroshima atomic bomb. That is about 2,800 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 63,000 times more than this one.

Aftershocks

In the first 6 days after it, USGS recorded 56 smaller earthquakes of magnitude 2.5 or more within 100 km (62 mi). The largest was a magnitude 5.9 on October 24 at 08:56 UTC.

A stronger magnitude 6.9 followed on October 24 at 02:31 UTC, about 9 km (5 mi) away, so this one is now considered a foreshock.

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 303 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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