M7.3 earthquake in Vanuatu region

Saturday, October 2, 2021, 06:29:17 UTC · 21.127°S, 174.896°E

A magnitude 7.3 earthquake struck in Vanuatu region on Saturday, October 2, 2021, 06:29:17 UTC, at a depth of 527.0 km (deep). USGS received 15 “Did You Feel It?” reports, with a maximum reported intensity of IV (light). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M7.6 on March 3, 1990.

Tsunami flagUSGS sets this flag for large events in oceanic regions so tsunami warning centers review them. It does not by itself mean a tsunami occurred. Check tsunami.gov and local authorities for official messages.

Magnitude: 7.3; Major · mww
Depth: 527 km; Deep
Felt reports: 15; Max intensity IV
Est. shaking: IV; Light (ShakeMap)
PAGER alert: Green; Impact estimate
Tsunami: Flag; Check tsunami.gov

Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

1.3 megatons of TNT

That is about 89 times the Hiroshima bomb. It released about 2,818 times the energy of a magnitude 5.0.

Tectonic setting

76 km

from the nearest mapped plate boundary, between the Australian and Conway Reef plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: deep

527 km

Deep earthquakes (over 300 km) happen deep inside subducting plates. They rarely cause damage, but can be felt faintly over very large distances.

Did You Feel It?

Where it was felt

Reports sent by people to USGS, grouped by place (most reports first). Intensity uses the Modified Mercalli scale (I–X): what people felt, not the magnitude.

Place	Intensity	Reports	Distance
Nadi, Western, Fiji Islands	II · Weak	4	695 km
Suva, Central, Fiji Islands	III · Weak	2	724 km
Isangel, Tafea, Vanuatu	IV · Light	1	808 km
Nukuʿalofa, Tongatapu, Tonga	III · Weak	1	1154 km
Deuba, Central, Fiji Islands	III · Weak	1	691 km
Lautoka, Western, Fiji Islands	II · Weak	1	707 km
Mont-Doré, Sud, New Caledonia	II · Weak	1	1017 km
Vila, Shefa, Vanuatu	II · Weak	1	946 km
Sola, Torba, Vanuatu	II · Weak	1	1237 km
Nouméa, Sud, New Caledonia	II · Weak	1	1029 km
Honiara, Guadalcanal, Solomon Islands	I · Not felt	1	2131 km

I felt it — report to USGS ↗

USGS PAGER estimate

Who was exposed to shaking

Modelled from the ShakeMap and population data. Alert level green: low likelihood of casualties and damage.

IV · Light shaking: 3,700 people
III · Weak shaking: 1.4 million people
II · Weak shaking: 173,000 people

After the main event

Aftershocks within 200 km

USGS lists 7 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M6.9 on October 9, 2021. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 236 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 3 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:

1990M7.6
Fiji Islands
3 Mar 1990 · 114 km away
2016M7.2
Loyalty Islands
12 Aug 2016 · 237 km away · intensity VI
tsunami
2017M6.9
Fiji Islands
3 Jan 2017 · 229 km away · intensity VI
tsunami

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers