Vanuatu earthquake: M6.9 off Espiritu Santo, then deeper M6.1

Key takeaways

• A shallow magnitude 6.9 earthquake struck off northern Vanuatu at 02:31 UTC on 24 October, about 197 km west-northwest of Port-Olry on Espiritu Santo, according to the US Geological Survey (USGS).
• USGS lists 40 Vanuatu-region earthquakes of magnitude 4.5 or greater between that shock and a deeper M6.1 near Port-Olry at 02:24 UTC on 25 October.
• A tsunami warning for parts of Vanuatu was issued and later lifted, AFP and 1News reported; USGS PAGER rated both large shocks green.
• Agencies disagree slightly on size: Germany's GFZ put the main shock at 7.0, and the first estimate was 7.2.
• Initial reports from AFP and DPA said there were no immediate reports of damage or casualties. Officials have not yet published a full damage assessment.

A Vanuatu earthquake sequence began with a shallow M6.9 at 02:31 UTC on 24 October, about 197 km west-northwest of Port-Olry on Espiritu Santo. USGS lists 40 quakes of M4.5+ before a deeper M6.1 struck near Port-Olry at 02:24 UTC on 25 October.

Vanuatu earthquake today: what happened

The main shock hit at 02:31:28 UTC on Saturday 24 October, or about 1:31 pm in Vanuatu (UTC+11). USGS gives a moment magnitude (Mww) of 6.9 and places the epicentre at 14.06°S, 165.55°E, in open ocean roughly 200 km west of Sola on Vanua Lava and northwest of Espiritu Santo. Its depth is listed at 10 km, but USGS marks that value as "operator assigned". That means the agency fixed a standard shallow depth instead of measuring it precisely.

Four minutes later, at 02:35 UTC, an M6.3 (body-wave magnitude, mb) struck about 170 km northwest of Port-Olry. Through the rest of Saturday, USGS recorded a steady run of M4.5 to M5.8 events in the same patch of seafloor. Most were placed between 160 km and 240 km northwest of Port-Olry. One of the largest later shocks was an M5.9 (Mww) at 08:56 UTC on 24 October.

At 02:24 UTC on Sunday 25 October, an M6.1 (Mww) occurred 25 km east-northeast of Port-Olry at a depth of about 116 km. That is roughly 200 km east-southeast of the main shock and much deeper. Some outlets citing GFZ described it as the strongest aftershock. However, the USGS locations show a different setting: shallow offshore shaking in the northwest swarm, and an intermediate-depth event beneath northeastern Santo. Seismologists have not publicly said whether the two are physically linked.

The largest shocks in the sequence

The table compares the reviewed USGS solutions with the automatic GFZ list for the biggest events. Times are UTC. USGS data were retrieved at 07:12 UTC on 25 October.

Not every event in the 40-quake count belongs to the offshore swarm. USGS also logged an M5.5 at about 195 km depth north-northeast of Port-Olry on 24 October and an M4.9 southwest of Isangel on Tanna, far to the south. Both are typical of Vanuatu's background activity.

Tsunami warning issued, then lifted

According to AFP, the Pacific Tsunami Warning Center first said hazardous waves were possible for parts of Vanuatu. Vanuatu's geohazards authorities then urged people in coastal areas to move to higher ground. 1News reported that the centre identified no threat area for New Zealand at that stage. In a later bulletin, the warning centre said the threat had passed, AFP reported. It also lowered its magnitude estimate from 7.2 to 6.9.

The USGS event page carries a "tsunami" flag for the M6.9. This flag only shows that the quake was large enough, and in the right region, for tsunami centres to issue messages. It does not mean a wave was observed. No damaging tsunami had been reported as of the latest reports we reviewed. USGS shows no tsunami flag for the Sunday M6.1.

Why do the magnitudes differ between agencies?

Readers comparing reports have seen 6.9, 7.0 and 7.2 for the same quake, and 6.1 or 6.16 for Sunday's event. The USGS explains that magnitude types use different methods. Mww is a moment magnitude calculated from long-period W-phase waves, and mb is based on the amplitude of early P-waves. Even when agencies use the same type, their results can differ by up to about 0.5 because they use different Earth models, station data and processing.

Early figures are usually automatic and are revised as more data arrive. The 7.2 was a first estimate. USGS's reviewed Mww of 6.9 and GFZ's automatic 7.0 are within the normal spread. Depths also vary: USGS puts the M6.1 at 116 km, while GFZ's automatic solution lists 141 km.

The New Hebrides subduction zone behind the swarm

Vanuatu sits above the New Hebrides subduction zone, where the Australian plate descends beneath the New Hebrides microplate. That process built the volcanic island chain. Convergence rates along the system vary widely. Published estimates range from about 40 mm a year in the central section, where the d'Entrecasteaux Ridge is being pushed into the trench near Santo, to around 120 mm a year in the south. They are faster still in the far north toward the Solomon Islands.

Shallow swarms like Saturday's, with many similar-sized shocks clustered offshore, are common in this setting. Deeper events such as Sunday's M6.1 usually occur inside the sinking plate. They typically cause less shaking at the surface than a shallow quake of the same magnitude. USGS's ShakeMap estimated a maximum intensity of about IV for the M6.1, and its PAGER system expected limited impact.

The region has a record of large earthquakes. Notable events include an M7.8 near Sola in 2009 and an M7.3 east of Port Vila on 17 December 2024, which caused deaths and heavy damage in the capital.

What is still unknown

• Damage on Santo and the Banks and Torres islands: early wire reports (AFP, DPA) cited no immediate damage or casualties, but remote northern islands are hard to reach and assessments can take days.
• Whether the swarm is ending: USGS was still logging M4.7 to M5.1 events offshore into early 25 October UTC.
• The link between the two largest shocks: no agency has yet published an analysis that ties the deep M6.1 to the shallow M6.9 sequence.
• Official guidance: the Vanuatu Meteorology and Geo-hazards Department (VMGD) is the national authority for earthquake and tsunami alerts. Its website had not posted a detailed summary of the sequence when we checked.

What it means

For residents and travellers in northern Vanuatu, the practical message is unchanged: long or strong shaking near the coast is itself a warning to move to higher ground, without waiting for an official alert. Aftershock sequences after an M6.9 can last weeks, and a later shock can occasionally be larger than the first. For everyone else, the green PAGER ratings and early reports suggest a strong but so far low-impact sequence. That picture will be confirmed only when VMGD and Vanuatu's disaster authorities publish their assessments. For more coverage, see our Vanuatu, Earthquake and USGS topic pages.

Sources

• USGS: M 6.9 – 197 km WNW of Port-Olry, Vanuatu (24 Oct 2026)
• USGS: M 6.3 – 170 km NW of Port-Olry, Vanuatu
• USGS: M 5.9 – 196 km NW of Port-Olry, Vanuatu
• USGS: M 6.1 – 25 km ENE of Port-Olry, Vanuatu (25 Oct 2026)
• USGS: M4.5+ earthquakes, past day (feed generated 07:12 UTC, 25 Oct)
• GFZ GEOFON: latest earthquake list
• USGS: Magnitude types
• USGS FAQ: Why do USGS earthquake magnitudes differ from other agencies?
• New Straits Times (AFP): Tsunami warning lifted after earthquake off Vanuatu
• 1News: Shallow 6.9 magnitude earthquake rattles Vanuatu
• Yahoo News (DPA): Powerful 6.9-magnitude earthquake strikes Vanuatu
• Vanuatu Meteorology and Geo-hazards Department
• New Hebrides Trench (background and convergence rates)