Lake Taupō sits on a massive pocket of 'magma mush', scientists say
Tuesday, 22 June 2021
Scientists have pieced together some clues leading them to believe there is a “magma mush” reservoir underneath Lake Taupō.
The discovery comes after a string of seismic activity at Lake Taupō in 2019, which revealed more about the belly of world's most active supervolcano system.
In 2019 the lake saw multiple earthquake swarms and ground deformation, allowing scientists to estimate there is a 250 cubic kilometre magma mush reservoir beneath the lake.
In a study published in the journal Geochemistry, Geophysics, Geosystems on Tuesday, researchers said new magma feeding into the reservoir caused the quake flurry in 2019.
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Taupō is a caldera volcano; it has a large cauldron-like hollow which formed after its magma chamber emptied during a huge, past volcanic eruption. According to researchers, it has been very active in recent geological time, but has not erupted for about 1800 years.
There have, however, been periods of unrest involving abundant and sometimes damaging earthquakes and ground deformation, but no eruption.
In 2019, the Taupō volcano underwent one of these periods of unrest – there was a significant increase earthquakes and ground deformation within the caldera. There were about seven distinct swarms, involving clusters of earthquakes.
The 2019 action was the most significant period of activity in the Taupō region in the past few decades, with hundreds of earthquakes occurring, including a magnitude 5.3 earthquake, the scientists state in their study.
The authors explain how they used the locations and patterns of the earthquakes and ground deformation to conclude that beneath the caldera there was an active magma reservoir of at least 250 cubic kilometre volume, and which is at least 20–30 per cent molten.
New magma being fed into the reservoir caused the earthquakes in the surrounding crust along fault lines that reflect both the volcano structure and the regional rift faults that cut across the volcano, the scientists said.
“Our findings show that Taupō needs to be carefully monitored to better understand the processes at depth and the factors that might cause similar unrest to escalate into an eruption in the future,” the authors said.
“…Any unrest event that can be demonstrated to involve magma movement and segregation, as with the 2019 unrest, can be inferred to represent a potential eruption. While it is far more likely that unrest events will not lead to an eruption, identifying the tipping-points and associated signals which may indicate an impending eruption is a vital research area for Taupō and caldera volcanoes worldwide.”