Scenic View Of Mount Tauhara And Lake Taupō on New Zealand’s North Island.
Lake Taupō is the largest freshwater lake in Oceania, located in the center of New Zealand’s North Island. It is a caldera lake, filling a large cauldron-like depression that formed shortly after the emptying of a magma chamber in a volcanic eruption.
The Taupō volcano produced two of the world’s most violent eruptions in geologically recent times. About 30,000 years ago, the first massive eruption coated the North Island in a thick layer of ash and igneous rock. About 2,000 years ago, the volcano erupted again, with New Zealand’s largest eruption known so far. Taupō volcano is considered still active.
On September 20th, authorities raised its alert level for the first time on record from 0 – low-level thermal activity near the volcano – to 1 – minor unrest with a low possibility of minor steam eruptions, gas emissions, and earthquakes. This change was made in response to more than 700 earthquakes registered since May 2022 and a 6-centimeters uplift of the eastern section of the lake’s floor, suggesting that magma and hydrothermal fluids are on the move deep beneath the caldera.
The Volcanic Alert Level system is based on 6 levels, ranging from normal background activity found in a volcanic area, like hot springs and geysers, to a major volcanic eruption with far-reaching effects, like massive ash and gas emissions.
Despite the raised alert, an imminent eruption is extremely unlikely at this time. Large caldera systems such as Yellowstone can experience episodic signs of unrest with earthquake swarms and surface changes due to normal movements of molten rock in the underground, fracturing the surrounding bedrock.
In a 2021 study, the authors summarize what we know so far about supervolcanoes, concluding that there is not a single model which can describe how these catastrophic events play out, making it extremely difficult to determine how supervolcanoes may erupt in the future.
Supervolcanoes are defined as a volcano that has had at least one explosion of magnitude 8, the highest ranking on the Volcanic Explosivity Index, or VEI, meaning it has released more than 1,000 cubic-kilometers of material during an eruption. The most powerful eruption in modern times was the VEI 7 eruption of Mount Tambora about 200 years ago.
When these huge volcanic systems explode, the associated supereruption represents the most catastrophic of events caused by a terrestrial natural hazard, resulting in widespread ash-fall blankets and 700 to 1,000°C hot debris avalanches, which can be hundreds of meters thick, covering thousands to tens of thousands of square kilometers.
However, such powerful eruptions are extremely rare, occurring maybe once every 100,000 to 1,000,000 years.
