Photo: 123RF
GNS Science says it has recorded more than 80 earthquakes in the Hawke's Bay and Te Tairāwhiti regions since they started this week.
The swarm of shallow but frequent tremors began on Tuesday just before 6am.
Seismic duty officer Elisabetta D'Anastasio said the tremors were recorded about 20 kilometres north-east of Wairoa in Hawke's Bay.
The largest - a 4.5 magnitude quake - was felt by 240 people early on Wednesday morning.
D'Anastasio said such swarms were "not uncommon" in the area.
"It's quite common to have this cluster of increased seismicity in Wairoa and also the whole east coast."
The quakes were on a known set of fault lines running from the steep hill country north-east of Wairoa to the east coast between Mahia and Gisborne.
The light shaking was likely to taper off in the next few days, and swarms were a good reminder to be prepared for a big quake, she said.
"The swarm we're observing right now so far doesn't indicate anything concerning but it's always a possibility that we can't predict."
She said the swarm could be "very upsetting" for people who felt the tremors, but the best thing was to be prepared.
"We live in a very active country in terms of tectonics and it's very good to use these swarms as reminders and know what to do in case of large events."