Location:

Magnitude:

7.1

Time:

7 Dec 2023 12:56:30

Depth:

48.0

M 7.0+:

M 7.0; 133 km SSE of Isangel, Vanuatu; (3 Sep 2011) (42km from the earthquake)
M 7.0; 118 km NNE of Tadine, New Caledonia; (13 Jan 2011) (87km from the earthquake)
M 7.3; LOYALTY ISLANDS; (9 Apr 2008) (71km from the earthquake)
M 7.3; 71 km SW of Isangel, Vanuatu; (9 Apr 2008) (74km from the earthquake)
M 7.1; 119 km S of Isangel, Vanuatu; (25 Mar 2007) (5km from the earthquake)

There are 11 swarms found nearby.

2006

PS20060524.1(41.1km)

24 May

12 hours

5 earthquakes

2007

PS20070404.2(47.7km)

3 Apr

20 hours

6 earthquakes

PS20070927.1(87.0km)

27 Sep

20 hours

26 earthquakes

PS20070929.1(65.2km)

29 Sep

1 hours

5 earthquakes

PS20071014.1(65.0km)

13 Oct

18 hours

5 earthquakes

2008

PS20080409.1(59.0km)

8 Apr

2 days 13 hours

21 earthquakes

PS20080411.2(61.5km)

11 Apr

2 hours

5 earthquakes

2011

PS20110113.1(64.4km)

13 Jan

1 day 9 hours

18 earthquakes

PS20110510.1(95.8km)

10 May

1 day 1 hours

24 earthquakes

2016

PS20160619.1(70.4km)

18 Jun

1 day 7 hours

8 earthquakes

2023

PS20231224.2(53.8km)

23 Dec

20 hours

5 earthquakes

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Seismic Activity in Southern Vanuatu: The December 2023 M7.1 Earthquake and Regional Context

Vanuatu lies along the convergent boundary between the Pacific and Australian plates, where subduction drives intense seismic activity. The island arc forms part of the Pacific Ring of Fire, with the New Hebrides subduction zone producing frequent moderate-to-large earthquakes at depths typically ranging from 10 to 200 km.

On 7 December 2023 at 12:56 UTC, a magnitude 7.1 earthquake struck 118 km south of Isangel on Tanna Island. The event occurred at a focal depth of 48 km. This location places the hypocenter within the subducting slab, consistent with intermediate-depth intraslab seismicity common in the region.

Since 2000, several comparable events have occurred nearby. A magnitude 7.0 earthquake took place on 3 September 2011, 133 km southeast of Isangel. Another magnitude 7.0 event occurred on 13 January 2011, 118 km northeast of Tadine in New Caledonia. On 9 April 2008, two magnitude 7.3 earthquakes struck the Loyalty Islands region, one 71 km southwest of Isangel. A magnitude 7.1 event was also recorded on 25 March 2007, 119 km south of Isangel. These earthquakes cluster within roughly 90 km of one another, reflecting persistent strain accumulation along the same segment of the subduction interface and slab.

Geologically, the southern Vanuatu arc experiences both interplate thrust earthquakes and intraslab normal or strike-slip faulting. Depths around 40–50 km often correspond to dehydration embrittlement within the downgoing plate. Historical records show recurrence intervals for magnitude 7+ events in this sector on the order of several years, underscoring the area’s elevated seismic hazard.

No significant tsunami was generated by the 2023 event, consistent with its depth and focal mechanism. Regional monitoring networks operated by the Vanuatu Meteorology and Geo-Hazards Department and international agencies continue to track aftershock sequences and background seismicity.

USGS Earthquake Catalog
Global CMT Project
Vanuatu Meteorology and Geo-Hazards Department Annual Reports