Northern Vanuatu spent Saturday afternoon and evening being shaken again and again. The first big jolt, measured at magnitude 6.9, struck around 1:30pm local time in the sea roughly 200 kilometres west-northwest of Port-Olry on Espiritu Santo. Four minutes later a 6.3 jolt followed from almost the same spot, both very shallow at about ten kilometres below the seabed.
Early readings had put the main shock at 7.2, high enough for the Pacific Tsunami Warning Center to flag possible dangerous waves along coasts within 300 kilometres. Vanuatu’s Geological Hazards Department lifted its own warning later in the afternoon after tide gauges showed nothing threatening. Australia’s weather bureau said there was never a risk to its shores.
The ground, however, kept moving. By Sunday morning US seismologists had logged more than 20 further events in the area, many above magnitude 5. Three of them, between 5.3 and 5.8, arrived within a quarter of an hour in the early evening, and a 5.9 hit shortly before 10pm.
So far nobody has reported serious damage or casualties, but officials cautioned that information from the remote communities closest to the epicentre is still patchy.
Quakes are part of life in Vanuatu, an archipelago of more than 80 islands strung along the Pacific Ring of Fire. What stands out this week is the frequency: a strong tremor had already rattled the same stretch of ocean on Tuesday without generating a tsunami. Scientists will be watching whether this sequence slowly fades or signals that stress along the plate boundary has not yet been fully released.
