Nearly 200 earthquakes have been recorded since Thursday near the active marine volcano, which lies about 50 kilometres offshore from Whakatane.
GeoNet says over the last 24 hours the rate and magnitude of the quakes had increased.
It says the activity doesn't appear to be linked to volcanic unrest, but it may result in increased landslide risk on the island.
The largest of the swarm was magnitude 3.8.
