GNS Science says Lake Taupo earthquake swarm not linked to volcanic activity change

A swarm of shallow earthquakes at Lake Taupo aren't linked to a change in volcanic activity, GNS Science says.

On Wednesday night, two large earthquakes 15km northeast of Turangi rattled the region. At 7:02pm, a magnitude 5.2 shake struck at a depth of 5km, followed two minutes later by a magnitude 4.5 aftershock. 

This set off a sequence of 80 smaller shakes and sparked some online to question if "the Taupo volcano waking up?"

"Taupo is a dormant, not extinct, volcano.  Bit scary for the locals I'd imagine," said one person.

But GNS Science has shut down any suggestion an eruption is imminent, saying on Thursday: "There is no indication that these earthquakes are linked to a change in volcanic activity".

"The greater Rotorua-Taupo area is a rift zone. A wedge of the earth’s crust is being stretched due to plate boundary processes," GNS Science volcano duty officer Yannik Behr said in an update on Thursday.

"This stretching creates numerous faults which cause many earthquakes over time, including many smaller quakes clustered together as swarms."

Since 1980, there have been three shallow earthquakes of magnitude 5 or higher in the Lake Taupo region. There have been over 40 greater than magnitude 4.

Wednesday's earthquake swarm was similar to a sequence of shakes in July when 160 quakes were recorded in the Lake Taupo area over a week.

"Taupo is not the kind of volcano that could erupt without warning. It could have years of unrest and still not erupt. We know that it will erupt again sometime in the future, but right now there is nothing to worry about," GNS Science volcano duty officer Steven Sherburn said at the time.

According to GNS Science, Taupo is a "supervolcano" and "one of the most frequently active and productive rhyolite caldera in the world".

Roughly 1800 years ago, the 'Taupo Eruption' occurred, sending eruption plume 50km into the air and covering New Zealand in at least 1cm of ash. Areas near the lake were buried by more than 100 metres of debris. Red sunsets caused by the ash were seen in China and Rome.

While an eruption may not be something to be concerned about, one thing for residents near the lake to consider is tsunamis. Although they are rare, tsunamis can occur in large lakes after earthquakes. 

"Given New Zealand's geological makeup, this is something New Zealand communities should be more aware of," said NIWA marine biologist Joshu Mountjoy last year.