A swarm of nearly 50 small earthquakes have been recorded near Kawerau this morning.
GNS Science volcanologist Brad Scott said the first was recorded at 5am, and 46 had been located since, all in the area 15km South-West of Kawerau.
He said there had been more, but they were too small to locate.
The earthquakes ranged in magnitude from 1.2 to 3.7 which Scott said was not big, but had been reported as 'felt' by 173 people.
He said swarm activity like this was "really typical" for the Taupo Volcanic Zone and was nothing to be concerned about.
Swarms were clusters of earthquakes which are characterised by as having no main or large earthquake.
Earthquakes in a swarm were usually around the same size and were common in New Zealand, especially in volcanic regions, Scott said.
GNS Science Duty Seismologist Sam Taylor-Offord said although the swarm was occurring in an active volcanism area, the characteristics of the earthquakes were similar to those of a tectonic swarm.
"Leading us to hypothesise that the swarm is not volcanically-driven," Taylor-Offord said.
A message to the Rotorua Daily Post Facebook page said the earthquakes could be felt in Murupara, Kaingaroa and Reporoa.
The woman who sent the message said she could still feel smaller shakes.