Scientists keep close eye on Alpine Fault quake swarm

Scientists expect the Alpine Fault is likely to cause a major quake within this generation's lifetime. Photo / File

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.

Our friends at @geonet have recorded/reported on a few earthquakes over the past couple of hours across the South Island. Magnitude has been just under 5.0

Full details here: https://t.co/nVaojeZbA0 pic.twitter.com/iR8yUxWxQb

— NIWA Weather (@NiwaWeather) April 3, 2018

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.

"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."

Seems to be a wee swarm of activity near the Alpine fault this afternoon, don't forget to #DropCoverHold in an earthquake! And check out https://t.co/RRs8zhxKvr for what to do before, during and after an earthquake wherever you are in NZ @NZGetThru #eqnz

— GeoNet (@geonet) April 3, 2018

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.