GeoNet recorded several quakes in the Eastern Bay this morning. Photo / NZME
More than 20 small earthquakes have been detected off the coast of Whakatāne since 6am this morning, GNS Science says.
At least four shakes were felt in the Whakatane area with GeoNet recording the biggest at a 3.3 magnitude, 10km north of the town and at a depth of 4km at 8.10am.
The quake was initially recorded as a 4.3, but was soon downgraded.
A magnitude-3 quake was recorded at 5.27am in the same location, another 3 at 7.37am, and a 2.7 at 7.45am.
Several other quakes were recorded in the area by GeoNet this morning, but were described as "unnoticeable".
Residents have taken to social media describing the quakes with one person saying: "Another one just now!! Definitely felt and heard it."
Another described one as a "short sharp jolt".
Whakatāne resident Maaike Kuhn said she felt all the shakes.
"I live near the beach, after the 7.50am shake the waves sounded much louder, then same with the 8.10am shake. The waves would settle down after each shake".
She said the most recent one had the 'earthquake sound' to it.
Contacted for comment, GNS confirmed more than 20 earthquakes had been recorded in the area since 6am.
According to information on its website, unlike aftershocks swarm sequences tend not to have a dominant "mainshock" earthquake and are difficult to forecast.
They are relatively common internationally, but the Taupō Volcanic Zone from Ruapehu up through Whakaari/White Island is one of the most frequent areas for swarms.
Possible swarm causes included fluid interaction with existing faults, magma movement through the Earth's crust, and "slow slip" events - an earthquake in slow motion.
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