The Taupō tsunami was triggered by a ‘special type earthquake’

Lake Taupō.
Photo: RNZ / Rebekah Parsons-King

It is one of the furthest places from the ocean in New Zealand.

But in the middle of the night in 2022, a tsunami on Lake Taupō flooded the coastal area and damaged moored boats. The trigger was a magnitude 5.6 earthquake caused by unrest in the volcano beneath the lake.

GNS Science volcano seismologist Dr Oliver Lamb said Afternoon The tsunami was caused by a “quite unusual earthquake.”

“When people think of earthquakes, the classic model we see is… two big chunks of rock moving past each other,” he said.

“That’s not what we think happened that night in November 2022. What we think actually happened was a special type of earthquake, quite rare, that has only been seen at a few volcanoes in the world, called a trapdoor earthquake.

Trapdoor earthquakes were large sections of land behind the lake that moved upward, like a trapdoor, Lamb explained.

He and his team have about a dozen seismometers around the lake that provide them with data to study.

Lamb said learning as much as they could about volcanic activity would help the region be better prepared when the volcano erupts again.

Cracked and sunken ground on the shore of Lake Taupō after the earthquake on November 30.
Photo: Geonetwork

“Taupō (is) an active volcano, it has erupted in the past and will definitely erupt again in the future,” he said.

The last major eruption of Lake Taupō volcano was 1,800 years ago.

“The reason we do this is that we want to understand what is happening at the volcano during each shaking episode, and each shaking episode, the earthquake, teaches us new things about the volcano.

Lamb said that by studying the data, they could provide better advice to the public.