Violent Supervolcano Appears to Be Rumbling Back to Life

A supervolcano has had its alert level increased in the wake of 700 earthquakes occurring nearby.

Taupō volcano, which is a supervolcano situated underneath New Zealand's largest lake, Lake Taupō, had its Volcanic Alert Level (VAL) increased from 0 to 1 on September 20. Level 1 indicates minor volcanic unrest, according to GeoNet, a geological hazard agency in New Zealand.

Lake Taupō sits within the giant caldera of a supervolcano on New Zealand's North Island, roughly six miles above the magma chamber. The volcano has erupted 25 times in the last 12,000 years, most recently in the year A.D. 232, resulting in the largest and most violent eruption on Earth in the past 5,000 years.

Supervolcanoes, which also include Yellowstone, Long Valley in eastern California and Toba in Indonesia, are volcanoes that erupt with magnitude 8 or greater on the Volcano Explosivity Index, which means that deposits of the eruption are spread further than 240 cubic miles.

According to GeoNet, more than 700 earthquakes have been recorded beneath Lake Taupō in 2022, with an increase in the frequency of these earthquakes being seen since May, at depths between 2.5 and 8 miles beneath the lake.

This marks the first time that GeoNet has raised the VAL for Taupō volcano to to 1, however, there have been 17 previous episodes of similar volcanic unrest over the past 150 years, some of which were more severe than what is currently being observed. The VAL scale ranges between 0, with no volcanic unrest, and 8, which represents a mega-colossal volcanic eruption.

"None of these episodes, or the many other episodes which would have occurred over the past 1800 years before written records were kept, ended in an eruption," GeoNet said in a statement. "The chance of an eruption at Taupō remains very low in any one year."

The earthquakes near Lake Taupō have been caused by volcanic unrest, according to GeoNet, which is when magma or magma-heated hot water and steam force their way through the ground, leading to earthquakes and ground movement.

Research published in the New Zealand Journal of Geology and Geophysics in February found that the ground under Lake Taupo has been shifting. According to the paper, the ground at the southern end of the lake sank by 5.5 inches, while at the north-eastern section, with the most active vents, the ground rose by around 6.3 inches.

According to GeoNet, Taupō's volcanic unrest could continue for months without any real eruption. However, it could cause landslides, resulting from earthquakes, mud lahars (a violent type of mudflow or debris flow) and ground subsidence.

Another New Zealand volcano hit the headlines in 2019 when White Island or Whakaari suddenly erupted as a tourist group was hiking on the island, killing 22 people and seriously injuring 25 others.

"Taupō will most likely erupt at some stage over the next few thousand years—and so it's important that we monitor and understand these unrest periods so that we can quickly identify any signs which might indicate a forthcoming eruption," Victoria University of Wellington seismologist Finn Illsley-Kemp told the New Zealand Herald in 2021.