Geonet has reported 84 earthquakes under Lake Taupō in the past three weeks.

Two of these were over magnitude 3.

The depths ranged from three to 16km, and earthquakes in the Lake Taupō area were typically shallower than 15km.

The agency said Taupō was still active because it showed signs of volcanic unrest with small earthquakes, movement of the ground up and down, and changes in the geothermal fields in the area.

There had been at least 17 episodes of volcanic unrest at Taupō in the past 140 years that had been above the background levels.

The recent earthquake activity had been grouped in two places under the lake; a cluster around the north-east/southwest side of the east shore, and a cluster in the middle of the lake.

There had also been earthquakes to the north, around the Wairakei geothermal system.

Only a few of the larger quakes in this sequence have been felt locally.

According to GeoNet, earthquake swarms were common in the Taupō Volcanic Zone with several recorded each year.

These could be related to the active faults in the zone and volcanic processes at the caldera volcanoes such as Taupō and Okataina.

In the past 10 years, the agency had located more than 4200 earthquakes under the lake.

The recent earthquakes were in a similar location to a series of earthquakes in 2019 that were studied in detail by the ECLIPSE volcano research programme.

The study showed that the earthquakes were related to the margins of the hot mush zone under the volcano and were signs that the Taupō volcano was active.

Lake Taupō is a large caldera volcano with rare but unusually large eruptions.