Stealthy magma system explains lack of warning signals at Veniaminof volcano, Alaska

Veniaminof volcano on the Alaska Peninsula has a long record of eruptions that occur with little or no detectable warning. Despite the presence of eight permanent seismic stations and satellite monitoring using Interferometric Synthetic Aperture Radar (InSAR), most eruptions since 1993 have taken place without clear precursory signals.

Of the last 13 eruptions, only two were preceded by detectable warning signs. This pattern prompted researchers to examine the underlying magma system at Veniaminof and investigate how volcanoes behave prior to eruption.

Modeling magma movement below the surface

Researchers from the University of Illinois Urbana-Champaign and Southern Methodist University set out to test whether a sealed magma system could erupt without triggering any noticeable seismic activity or ground movement.

In open volcanic systems, such as Mauna Loa, magma and gases move more freely toward the surface, sometimes resulting in fewer clear warning signals. In contrast, closed systems, such as Campi Flegrei, typically accumulate pressure, which can cause ground uplift and increased seismicity before an eruption.

To figure out how eruptions might happen without these signals, the researchers built detailed thermomechanical models. They tested how changes in magma chamber shape, size, depth, and magma supply rate interact with the surrounding rock’s physical properties.

The team used COMSOL Multiphysics to create models incorporating both temperature-dependent and temperature-independent rock behavior. They simulated magma transport from deep sources, more than 13 km (8 miles) below the surface, into shallower magma chambers with varying geometries.

To test how realistic these models were, they compared the results with InSAR and seismic data from Veniaminof’s 2018 eruption. The 2018 eruption is valuable because it showed no obvious ground movement or any preceding seismic activity, making it a good example of a quiet eruption.

#Veniaminof volcano in Alaska started erupting on Sept. 4! Video taken yesterday at 7:25 AM AKDT & shows low-level fountaining, incandescent flows and ash mantling intra-caldera ice. Courtesy of A. Eckert and Ace Air. See https://t.co/VQoNaTohbD for more info on current activity. pic.twitter.com/ttuMpsSstC

— Alaska AVO (@alaska_avo) September 13, 2018

Eruption style(s) depends on chamber dynamics

The main finding is that certain magma systems can erupt without producing detectable warning signals. Specifically, systems characterized by small, deep magma chambers, low magma supply rates, and heat-softened surrounding rock can produce eruptions with minimal ground deformation (less than 10 mm (0.39 inches)) and little to no seismicity related to shear failure, which typically causes earthquakes.

That said, some rock still fractured through tensile failure, which was enough to allow magma to rise and cause an eruption. In models where the rock’s behavior changed with temperature, a higher magma flux was needed to trigger this failure, but even then the surface signals remained weak.

InSAR analysis from 2015 to 2018 revealed no consistent uplift or subsidence patterns around the volcano, supporting the modeling results. Even during the 2018 eruption, displacement signals were ambiguous and likely masked by atmospheric interference or the glacier covering the summit.

These factors complicate the detection of subtle signs of volcanic inflation and support the conclusion that Veniaminof can produce eruptions with little or no surface warning.

The researchers also examined different combinations of chamber size and magma flux. High flux with a large chamber often led to detectable deformation, while low flux in a small chamber could fail to reach failure thresholds (meaning no eruption would occur).

The conduciveness for quiet eruptions came from moderate flux into moderately sized chambers, especially when the surrounding rock was already heated. This combination kept both seismic activity and surface movement low, but still allowed fractures to form inside the volcano.

Standard monitoring is not enough for quiet volcanoes

It’s still unclear whether Veniaminof behaves more like an open or closed system. Its frequent, low-warning eruptions have depicted open-vent behavior, but the geophysical data, like low gas emissions and inconsistent seismicity, indicate otherwise. On top of that, mineral and chemical inferences show that magma doesn’t flow in constantly but arrives in bursts instead.

InSAR coverage doesn’t extend well over the glacier-covered summit, which makes it harder to detect inflation signals even if they are present near the eruption source. Volcanoes like Shishaldin and Mount Cleveland have shown similar quiet eruption patterns.

Catching these events early takes more than standard monitoring tools. The study suggests upgrading ground-based instruments, using more sensitive seismic and InSAR techniques, and building models that can pick up on the finer details of how magma systems behave.

References:

¹ Stealthy magma system behavior at Veniaminof Volcano, Alaska – Yuyu Li, Patricia M. Gregg, et al. – Frontiers in Earth Science – June 10, 2025 – DOI https://doi.org/10.3389/feart.2025.1535083 – OPEN ACCESS