A magnitude 4.2 earthquake was one of hundreds recorded so far in the Kawerau earthquake swarm in Bay of Plenty, GeoNet says.

GeoNet has recorded over 600 earthquakes so far in the swarm, eight of which were over magnitude four.

"While many of these have caused felt shaking in the area, many more won't have been noticeable to humans — just to our seismic monitoring equipment," GeoNet said.

The 4.2 magnitude quake, felt at 10.42am, was 20km west of Whakatāne and was only 4km deep, with shaking described as light to weak.

Earthquakes have rocked the Bay of Plenty region since early Saturday morning.

A GeoNet spokesperson said residents in the area don't need to be alarmed.

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"Feeling earthquakes close together in time can be unsettling, but this is typical activity for the area, and our team is keeping an eye on things," they said.