Taupō's volcanic alert level is unlikely to shift after last night's big shake in the region, one researcher says.
Thousands of people reported feeling shaking after the magnitude 5.6 earthquake late last night.
It was centred 20km south-west of Taupō and struck around 11.47pm at a depth of nine kilometres, according to GeoNet.
Steve Sherburn, GNS Science's duty volcanologist, told 1News there were "a couple of very small foreshocks" before the main event - and since then, there have been "well over" 150 aftershocks locally, including "maybe 20 or so" people felt.
But it's too early to tell if the magnitude 4.0 earthquake at 6.37 last night in a similar area was a foreshock, he said.
Will Taupō's volcanic alert level be affected?
Taupō's volcanic alert level is currently at one, "minor volcanic unrest". There are six possible levels, from zero to five inclusive.
Asked if that was likely to be affected by last night's tremor, Sherburn said: "I think probably not".
He explained that the alert level is decided in a vote by the Volcano Monitoring Group, an association of experts.
"For Taupō, we've been voting on the alert level for the last several months, and most people have been voting to remain at level one.
"I will be surprised if people voted to change the alert level, but it will be definitely something that we will review the next time we have a monitoring response meeting," he said, adding that was unlikely to be today and they routinely review it weekly.
"We're at 'minor volcanic unrest' at the moment, and if we were to increase it that would be 'moderate to major volcanic unrest', and I think we would probably have to see quite a bit more than a single large earthquake and its aftershocks to warrant doing that."
Has the earthquake led to much deformation?
Deformation is when the ground physically moves and shifts during an earthquake.
Sherburn said scientists were working today to see if there's any deformation after the magnitude 5.6 quake, and they were likely to get the results tomorrow.
Those results would "definitely" be a factor in peoples' votes on the volcanic alert level, he said.
"That's one reason why rushing into reassessing the alert level today would probably not be good, because we really wouldn't have all of the information that we needed."
He explained that scientists monitors deformation using sophisticated, sensitive systems dotted around the lake.
They work in a similar way to a car's GPS system, and can measure changes in position down to roughly 5mm.
What should people know for future earthquakes?
Sherburn lives in Taupō himself, and he and his wife felt the quake.
He stressed that the Drop, Cover and Hold guideline is the best advice for anyone caught in an earthquake, adding that planning ahead is also key; for example, by having water stored somewhere in case the supply in interrupted.
"It's probably the strongest quake we've felt in the 20 or so years we've lived at that house," he said.
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