Vanuatu’s offshore earthquake sequence prompts a tsunami alert that is later lifted
A magnitude 6.9 earthquake off northern Vanuatu was followed by another strong shock on 24 October. A warning about hazardous waves from the Pacific Tsunami Warning Center was subsequently lifted. Early assessments put expected humanitarian impact in the low category, while agencies differed on some magnitude and depth estimates.
Science··Morning
A regional tsunami warning is lifted
The regional tsunami threat assessment was closed by the Pacific Tsunami Warning Center after the earthquake sequence off northern Vanuatu, an island country in the southwest Pacific, on 24 October. Its initial bulletin had warned that waves could be hazardous within 300 kilometres of the epicentre, using 7.2 as the preliminary magnitude. The final bulletin revised that figure to 6.9 and said the threat had passed, while allowing for minor sea-level fluctuations.[1]
Two strong shocks receive different rapid estimates
The United States Geological Survey placed the first earthquake about 197 kilometres west-northwest of Port-Olry, at a depth of 10 kilometres. A second strong shock followed. Both the US agency and the European-Mediterranean Seismological Centre assigned it magnitude 6.3, compared with 6.5 in Vanuatu’s national catalogue. Vanuatu’s Meteorology and Geo-Hazards Department agreed on magnitude 6.9 for the first earthquake but placed it 20 kilometres deep.[1]
Early impact assessments remain in the low category
No damage or casualties had been reported in the initial account from The Watchers. Rapid assessments from the Global Disaster Alert and Coordination System and the US agency were Green, indicating low expected impact. The global system estimated that roughly 40,000 people experienced intensity-IV shaking in the first event and 4,000 in the second. Those figures estimate exposure, rather than injuries. The sequence occurred offshore along an active convergent plate boundary; the initial accounts remain distinct from a completed damage assessment.[1]
