Key Takeaways

  • A magnitude 6.9 earthquake struck about 197 kilometres west-northwest of Port Olry at a depth of 10 kilometres.
  • A magnitude 6.3 quake followed four minutes later, with at least eight additional tremors above magnitude 5.
  • The tsunami threat was lifted less than an hour after the mainshock, though minor sea-level changes remained possible.

A powerful earthquake struck off the coast of Vanuatu in the South Pacific on Saturday, briefly triggering a tsunami threat for nearby coastlines before officials confirmed the danger had passed. There were no immediate reports of damage or casualties.

Two strong quakes, minutes apart

The U.S. Geological Survey (USGS) recorded the main earthquake at magnitude 6.9 at 02:31 GMT on Saturday, October 24 (1:31 p.m. local time). Its epicentre was about 197 kilometres west-northwest of Port Olry, on the island of Espiritu Santo, at a shallow depth of 10 kilometres. The quake was initially estimated at magnitude 7.2 before being revised down to 6.9.

Just four minutes later, a second earthquake of magnitude 6.3 struck nearby, about 170 kilometres northwest of Port Olry. At least eight further tremors above magnitude 5 were recorded in the hours that followed. The USGS estimates roughly 40,000 people were in the zone of light shaking.

Tsunami threat declared over

The Pacific Tsunami Warning Center issued a tsunami threat message after the first quake, warning that hazardous waves were possible along coastlines within 300 kilometres of the epicentre. Vanuatu's geological hazards officials advised coastal residents to move to higher ground.

At 03:28 GMT — less than an hour after the mainshock — the centre confirmed the tsunami threat had passed, though minor sea-level fluctuations remained possible near the epicentre for several hours.

A quake-prone nation

Vanuatu, an archipelago of about 80 islands, sits on the Pacific "Ring of Fire," where tectonic plate movements make earthquakes and volcanic activity common. A magnitude 6.3 quake also struck the country earlier the same week, on October 20, without a tsunami threat.

Sources

Photo: Simon_sees / Wikimedia Commons (CC BY 2.0) — a jungle road on Espiritu Santo, Vanuatu.

Sources