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A swarm of earthquakes occurred in the night near Lake Rotoma, northwest of Rotorua.
The first of the series of small earthquakes was recorded at 5pm.
What the earthquakes look like on the GNS seismograph.
The largest quake in the series was 3.5 on the Richter scale recorded at 8.30pm.
The swarm tailed off after this.
Swarms differ from typical tectonic earthquakes as there is no clear main shock/aftershock sequence.
The largest event can sometimes occur in the beginning of the sequence, near the middle like this one, or at the end.
Often many of the larger events in the sequence will also be about the same magnitude. In last night’s sequence, 11 of the events were between magnitude 2.4 and 2.8.
GNS scientists say this is a classic swarm sequence with the first discrete event occurring at about 5pm. By 8pm the quakes were semi-continuous.
The earthquake epicentres are clustered near Lake Rotoma to the northwest of Rotorua. Swarms of small shallow earthquakes are reasonably common in the Taupo Volcanic Zone between Ruapehu and White Island.
