More than 80 quakes detected around Lake Taupō
Saturday, 21 May 2022
GeoNet’s earthquake monitoring network has recorded a swarm of more than 80 earthquakes around Lake Taupō in less than a month.
However, the vast majority were not felt locally, with only two of them registering over magnitude 3.
GNS Science volcano information specialist Brad Scott said a total of 84 quakes were recorded under Lake Taupō at depths ranging from three to 16km, between April 28 and May 18.
“The recent earthquake activity has been grouped in two places under the lake,” Scott said.
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“[There is] a cluster trending northeast to southwest along the east shore and a cluster in the middle of the lake.
“There have 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.”
Scott said earthquake swarms were common in the Taupō Volcanic Zone (TVZ), with several recorded each year.
The swarms can be related to active faults in the TVZ and volcanic processes at caldera volcanoes like Taupō and Okataina.
Larger ones have lasted weeks-to-months and can include many hundreds of earthquakes.
“In the last 10 years we have located over 4200 earthquakes under Lake Taupō,” he said.
“These are part of the activity that defines the background level of unrest for Taupō volcano.”
He said variations in the level of background unrest were common for caldera volcanoes like Taupō.
”We know that Taupō is still active because it shows signs of what we call ‘volcanic unrest’ - small earthquakes, movement of the ground up and down, and changes in the geothermal fields in the area.”
Meanwhile, the volcanic alert level for Mt Ruapehu remains at Level 2 and volcanic tremor levels for the mountain have dropped from strong to moderate levels.
The crater lake (Te Wai ā-moe) temperature has also declined from 41C to 37C since May 8.
The level of gas emissions remains high, indicating the volcano is still at a heightened level of unrest.