Erupted Volume During the 2014–2023 Semisopochnoi Unrest and Eruption Constrained by Multi‐Platform InSAR and Volcanic Gas Observations
- 1Geophysical Institute University of Alaska Fairbanks Fairbanks AK USA
- 2U.S. Geological Survey Cascades Volcano Observatory Vancouver WA USA
- 3U.S. Geological Survey Alaska Volcano Observatory Anchorage AK USA
Abstract
Volcano deformation data provide important constraints on magma dynamics during volcanic unrest and eruptions. From these observations, we can estimate subsurface pressure changes and relate them to volume change in the reservoir. However, because magma and rock are compressible, this volume change cannot be directly equated with eruptive volume. When we combine geodetic analyses with gas observations, petrologic constraints, volatile solubility modeling, and magma compressibility equations, however, we can estimate realistic lower and upper bounds of eruptive volume. Leveraging multi‐platform InSAR time series and satellite SO2 data, we apply these methods to the 2014–2023 unrest and eruption of Semisopochnoi, Alaska. We find that this phreatomagmatic eruption sequence was fed by a spherical magma source at 6.5–7.5 km depth bsl, centered beneath the caldera, ∼5 km offset to the east from the vent. Volatile solubility modeling indicates that ∼50% of the initial dissolved CO2 has exsolved at depths consistent with the geodetic source depth, increasing the magma compressibility. Combining geodetic model constraints with SO2 observations, petrologic constraints, solubility models, and magma compressibility findings yields 12–32 Mm3 as the most‐likely juvenile, dense‐rock equivalent eruptive volume, with a best estimate of 20 Mm3. Stress change modeling suggests that the local stress field encouraged conduit formation west of the pre‐eruptive inflation center, and that the 2014 M7.9 Rat Island earthquake, ∼65 km to the west of Semisopochnoi, reduced the compressive stress underneath the volcano, supporting prolonged eruptive activity.
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BibTeX
@article{angarita2026erupted,
title = {{Erupted Volume During the 2014–2023 Semisopochnoi Unrest and Eruption Constrained by Multi‐Platform InSAR and Volcanic Gas Observations}},
author = {Mario Angarita and Valerie Wasser and Ronni Grapenthin and Allan Lerner and Taryn Lopez and Revathy M. Parameswaran and John Lyons},
journal = {Geochemistry, Geophysics, Geosystems},
year = {2026},
month = oct,
doi = {10.1029/2026gc013083},
url = {https://doi.org/10.1029/2026gc013083},
note = {CC BY},
}
RIS
TY - JOUR
TI - Erupted Volume During the 2014–2023 Semisopochnoi Unrest and Eruption Constrained by Multi‐Platform InSAR and Volcanic Gas Observations
AU - Mario Angarita
AU - Valerie Wasser
AU - Ronni Grapenthin
AU - Allan Lerner
AU - Taryn Lopez
AU - Revathy M. Parameswaran
AU - John Lyons
PY - 2026
DA - 2026/10/28
JO - Geochemistry, Geophysics, Geosystems
DO - 10.1029/2026gc013083
UR - https://doi.org/10.1029/2026gc013083
AB - Volcano deformation data provide important constraints on magma dynamics during volcanic unrest and eruptions. From these observations, we can estimate subsurface pressure changes and relate them to volume change in the reservoir. However, because magma and rock are compressible, this volume change cannot be directly equated with eruptive volume. When we combine geodetic analyses with gas observations, petrologic constraints, volatile solubility modeling, and magma compressibility equations, however, we can estimate realistic lower and upper bounds of eruptive volume. Leveraging multi‐platform InSAR time series and satellite SO2 data, we apply these methods to the 2014–2023 unrest and eruption of Semisopochnoi, Alaska. We find that this phreatomagmatic eruption sequence was fed by a spherical magma source at 6.5–7.5 km depth bsl, centered beneath the caldera, ∼5 km offset to the east from the vent. Volatile solubility modeling indicates that ∼50% of the initial dissolved CO2 has exsolved at depths consistent with the geodetic source depth, increasing the magma compressibility. Combining geodetic model constraints with SO2 observations, petrologic constraints, solubility models, and magma compressibility findings yields 12–32 Mm3 as the most‐likely juvenile, dense‐rock equivalent eruptive volume, with a best estimate of 20 Mm3. Stress change modeling suggests that the local stress field encouraged conduit formation west of the pre‐eruptive inflation center, and that the 2014 M7.9 Rat Island earthquake, ∼65 km to the west of Semisopochnoi, reduced the compressive stress underneath the volcano, supporting prolonged eruptive activity.
SN - 1525-2027
ER -