An earthquake that terrified locals appears to have produced a small tsunami in Lake Taupō which damaged boats.
GeoNet said the 5.6-magnitude earthquake, which happened at 11:47pm on Wednesday, was "strong". The quake was 20km southwest of Taupō and 9km deep.
At the time of writing, 5440 people had self-reported to GeoNet as having felt the earthquake. Eleven said it felt extreme, 69 severe, 552 strong, 1151 moderate, 1564 light and 2093 said it was weak.
People reported feeling the shake as far north as Whangārei and Dunedin in the south.
GNS Seismic Duty Officer John Ristau told Newshub it was quite a "sizeable earthquake" and one of the biggest ones they've had in a while.
Photos sent to Newshub appear to show part of the foreshore on Lake Taupō washed higher up onto the beaches and grass areas, which Ristau says was down to some sort of tsunami.
"There appears to have been some sort type of tsunami or what we might call a seiche which is when the water sloshes backwards and forwards like in a bathtub," Ristau explained.
"We aren't sure yet what the source of it was and exactly what happened but yes there does appear to be that, there was like a tsunami or a seiche."
A GNS spokesperson said tsunami-type waves in lakes can be caused by earthquakes, landslides, or even weather conditions. They said these have occurred in the past at Lake Taupō, according to historic records.
"Our experts are still looking at the earthquake activity at Lake Taupō from last night and at this point we don't know if this is just a seiche, just a tsunami or some combination of both," the spokesperson said.
Taupō Pedal Boats posted on its Facebook page that two of its boats were destroyed.
"There seems to have been quite a massive surge of water at the lake last night following the quake/s, which has uplifted our 2 boats from the grass, pulled them into the water & destroyed them, completely," Taupō Pedal Boats said.
Geonet said 150 earthquakes had been recorded since the initial quake with locals telling Newshub some of their items fell over and caused a sleepless night.
One resident said they were lying in bed when the earthquake hit.
"I thought for a second the person in the next room was shaking the wall or the bed because I was in a hostel," he said.
"I thought someone in the next room was just partying but then I realised oh no, this is shaking a lot. I've never felt an earthquake before but basically, it just felt like a subway was going underneath."
Another resident told Newshub the earthquake was "horrendous".
"I was lying in bed and the whole bed went up and down and moved. We lay there and it just kept coming and coming," she said.
"In the end, I got up and sat up until just after 3am while all the others were coming. But lord, it was scary."
She said one ornament, laundry powder and her deck chairs fell over because of the quake.
A third person said the earthquake really scared her.
"I literally sat up and sat there like I would normally and went oh s**t. I'm getting up and getting under the doorframe and stood there for the whole time absolutely scared," she said.
"It was a little bit hair-raising and everyone is talking about it this morning."
Ristau told Newshub the reason the earthquake didn't cause more severe damage was because it was beneath Lake Taupō.
"Another thing that plays a big role in how much damage an earthquake causes is the frequency content of the earthquake. So particularly if an earthquake puts out a lot of quite high-frequency energy, that's the kind of energy that causes a lot of really strong shaking and causes a lot of damage," he said.
"This earthquake didn't appear to have as much in those high frequencies, rather things concentrated more in the low-frequency, which means people will feel a lot of more slow low rolling type motion but not that really strong jolt, although I'm sure people felt that too."
