Ice-clad volcano study could help understand ‘stealthy’ eruptions

Volcanoes usually signal an upcoming eruption through ground deformation and earthquakes, giving people nearby a chance to evacuate safely.

What if a volcano were to erupt silently, without any of the usual signals? These are called “stealthy” volcanoes. And for scientists, they’ve been a dangerous mystery.

Dr. Yuyu Li and her team at the University of Illinois have developed a new model that could finally explain – and even predict – these silent threats. 

“Despite major advances in monitoring, some volcanoes erupt with little or no detectable precursors, significantly increasing the risk to nearby populations,” said Li, the lead author. 

“Our work helps explain how this happens, by identifying the key internal conditions — such as low magma supply and warm host rock — that make eruptions stealthy,” the author added. 

New model based on Alaskan volcano

Interestingly, Earth hosts some of the most peculiar types of volcanoes. 

For instance, there is one called Uturuncu volcano in Bolivia, also dubbed a “zombie” volcano. Despite not having erupted in over 250,000 years, it still exhibits signs of activity like earthquakes and gas emissions, indicating ongoing subsurface processes.

And then there are stealthy ones that erupt with little to no detectable precursory signals. 

Examples include volcanoes like Popocatépetl in Mexico, Merapi in Indonesia, or Stromboli in Italy – all located near communities or major air routes.

Understanding why stealthy behavior is important for improving volcanic hazard assessments and forecasting. 

In order to create the new model, the scientists chose to study Veniaminof, an ice-clad volcano in Alaska’s Aleutian Arc. 

Even though it’s closely watched, Veniaminof has only provided sufficient warning for 2 of its 13 eruptions since 1993. A 2021 eruption wasn’t even detected until three days after it started. 

“Veniaminof is a case study in how a volcano can appear quiet while still being primed to erupt,” said Li.

“It is one of the most active volcanoes in Alaska. In recent decades, it has produced several VEI 3 eruptions — moderate-sized explosive events that can send ash up to 15 km high, disrupt air traffic, and pose regional hazards to nearby communities and infrastructure — often without clear warning signs.” 

To crack the code, scientists built a model, feeding in data from Veniaminof’s 2018 stealthy eruption. They explored various scenarios: different magma chamber volumes, flow rates, depths, and shapes.

Stealthy eruption indications

What did they find? A high flow of magma into a chamber usually increases ground deformation – giving a clear warning.

But stealthy eruptions become likely when a low flow of magma enters a relatively small chamber. The data suggest that Veniaminof fits this profile: a small chamber with slow magma flow.

But there was another key factor: temperature. 

The model also found that warm surrounding rock, heated by the consistent presence of magma, makes the chamber’s size and shape less significant. This warm rock is less likely to produce detectable earthquakes or ground deformation, thereby increasing the chance of a stealthy eruption.

So, what’s next? Dr. Li emphasized the need for advanced monitoring: “To mitigate the impact of these potential surprise eruptions, we need to integrate high-precision instruments like borehole tiltmeters and strainmeters and fiber optic sensing, as well as newer approaches such as infrasound and gas emission monitoring. 

Moreover, machine learning is also showing promise in detecting subtle shifts.

By combining these innovative models with real-time observations, scientists are getting closer to unmasking these stealthy giants. 

The findings were published in the journal Frontiers in Earth Science. 

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