Seismologists are keeping a close eye on a "swarm" of quakes that have been recorded around the South Island's Alpine Fault.
But there's no immediate cause for alarm of a big shake along the fault, which poses one of New Zealand's biggest geological hazards.
More than a dozen quakes have been recorded around the boundary - running along the spine of the South Island - since yesterday, including four quakes that measured 4.4, 4.7, 3.8 and 3.1.
Activity now appeared to be tailing off, but the swarm served as a good reminder to people to be prepared, GNS Science's Dr Natalie Balfour said.
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"Any time there's activity near a large fault like the Alpine Fault, it always grabs our attention and we keep our eye on things."
Such clusters had been observed in the area in the past - the last swarm there was recorded after 2016's Kaikoura Earthquake - but the events remained "a bit unusual".
"We do get clusters of activity throughout New Zealand kind of like this - and it just means we need to pay a bit more attention to it."
Scientists expect the Alpine Fault is likely to cause a major quake within this generation's lifetime.
It last ruptured in 1717, or 301 years ago, and had a 28 per cent probability of rupturing in the next 50 years - a rate high by global standards.
According to GNS Science, this rupture would produce one of the biggest earthquakes since European settlement of New Zealand, and would have a "major impact" on the lives of many people.