The number of earthquakes at Lake Taupō have doubled over the past two weeks, taking the total to 840 since the start of 2022.
In September, minor volcanic unrest saw the volcanic alert level for Lake Taupō raised to level one for the first time. It’s remained at that level ever since.
GeoNet, the agency that monitors earthquake and volcanic activity in New Zealand, says there are two levels assigned to volcanic unrest; minor and moderate to heightened unrest. Volcanic Alert Level 1 is the lowest level of unrest – minor unrest.
In an update today, it said the rate of earthquake activity has varied since the increase started in May.
Paul Jarvis, volcano duty officer for GeoNet, told 1News the rate of earthquakes has been quite variable.
"Since the unrest started in May, some weeks have had less than 10 earthquakes whilst other weeks have had around 40. Periods of unrest like this are common at caldera volcanoes, like Taupō. Previous unrest episodes at Taupō have lasted from a few days to 3 years, so we can expect more to continue for now. The most common experience for people near Taupō volcano will be feeling small-moderate earthquakes."
Today's update said that after a peak of about 30-40 events per week from June to September, the number of earthquakes dropped over the last month to about 10-12 per week. This has now risen again, over the last two weeks, to a little over 20 events per week.
“We have now located 840 earthquakes since the start of 2022, mainly at depths from 4 to 13 km beneath the centre of Lake Taupō. The earthquakes in the last 2 weeks, the largest of which was magnitude 3.6 on 4 November, have been concentrated in the central portion of the lake, south of Horomatangi Reef.
“In addition to seismic activity, we also continuously monitor ground deformation (land movement) around Lake Taupō. Our GNSS (GPS) instruments around the lake continue to observe both horizontal and vertical changes. A site on Horomatangi Reef in the centre of the lake indicates that uplift at a rate of approximately 60 ± 20 mm per year has continued since May 2022.”
GeoNet says the Volcanic Alert Level reflects the current level of volcanic unrest or activity and is not a forecast of future activity.
Jarvis said the earthquakes were not related to the warmer weather or climate change.
“While Volcano Alert Level 1 is mostly associated with environmental hazards, potential for eruption hazards also exists.”
"If there is shaking, drop, cover and hold. It’s always good to have a plan and be prepared if you live in an area close to a volcano. The National Emergency Management Agency (NEMA) has a great website with information on what to do before, during and after volcanic activity," Jarvis said.
There have been 17 previous episodes of unrest at Taupō over the past 150 years and none have ended in an eruption.
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