Hazards associated with glacier-volcano interaction can vary from lava flows to volcanic ash, lahars, landslides, pyroclastic flows, submarine eruptions or glacial outburst floods. These can happen consecutively or simultaneously and affect not only the Earth, but also glaciers, rivers and the atmosphere. As accumulating, melting, ripping or drifting glaciers generate signals as well as degassing, inflating/deflating or erupting volcanoes, the challenge is to study, understand and ultimately discriminate these potentially coexisting signals. This challenge also extends to coastal and submarine environments, where coupled cryosphere–volcanic–oceanic processes can impact signals and deposition dynamics on the seafloor. We wish to fully include geophysical observations of current and recent events with geological observations and interpretations of deposits of past events.
We invite contributions that deal with the mitigation of the hazards associated with ice-covered volcanoes or studies focused on volcanic impacts on glaciers and vice versa. Research on recent activity is especially welcomed. This includes geological observations, e.g. of deposits in the field or remote-sensing data, together with experimental and modelling approaches. We particularly encourage abstracts that includes multi-scale and technology-driven approaches. We also invite contributions from any part of the world and other planets on past activity, glaciovolcanic deposits and studies that address climate and environmental change through glaciovolcanic studies.
Submarine volcanism in Antarctica remains one of the least explored yet geodynamically important processes on Earth. The Terror Rift, located in the western Ross Sea, is a zone of active extension, long-lived magmatism, and cryosphere–lithosphere interaction. Along its eastern boundary, the Lee Arch hosts several flat-topped seamounts that were previously interpreted as mud volcanoes based on vintage seismic data (Busetti et al., 2024). New evidence from Expedition NBP25-01 contradicts this interpretation (Tominaga et al., 2025). Rock samples from dredges and seafloor imagery confirm the presence of hyaloclastite breccia, hyalotuff, coherent lava fragments, ash, and agglutinated ash-lapilli, indicating a dominantly explosive volcanic origin for these edifices.
Here, we integrate new multichannel seismic profiles from Expedition NBP24-02 with reprocessed vintage multichannel data from Expedition IT-90RS, together with ground-truthing from Expedition NBP25-01, to assess the volcano–tectonic architecture of the Flapjack Field on the Lee Arch. The seismic profiles image extensive normal faulting along the eastern shoulder of the Terror Rift, with dense fault systems extending beneath the Flapjack Field. These fault corridors align with volcanic edifices and likely acted as preferential magma ascent pathways, enabling focused volcanism along the rift margin. Seismic images reveal a broadly consistent internal architecture across several flat-topped edifices, characterized by incoherent seismic facies in their central portions and spatially limited, outward-dipping stratified reflections forming progradational flank sequences. We interpret the incoherent central domains as massive hyaloclastite and breccia accumulated within confined eruptive cavities close to the vent, whereas the stratified flanks consist of volcaniclastic deposits emplaced by subaqueous density currents and gravity-driven mass flows. The general absence of pronounced seismic attenuation suggests that thick sequences of coherent volcanic rocks are absent, consistent with findings from Expedition NBP25-01 (Tominaga et al., 2025). The morphology and internal architecture support interpretation of these seamounts as subglacial volcanoes emplaced beneath grounded ice, analogous to tuyas or tindars. Our results demonstrate a tight coupling between fault-controlled magma ascent and subglacial volcanism along the eastern margin of the Terror Rift.
References:
Busetti, M., Geletti, R., Civile, D., Sauli, C., Brancatelli, G., Forlin, E., ... & Cova, A. (2024). Geophysical evidence of a large occurrence of mud volcanoes associated with gas plumbing system in the Ross Sea (Antarctica). Geoscience Frontiers, 15(1), 101727, https://doi.org/10.1016/j.gsf.2023.101727
Tominaga, M., Panter, K., Berthod, C., Tivey, M., Wu, J. N., Preine, J., ... & NBP25-01 Shipboard Science Support Staff. (2025). Subglacial explosive volcanism in the Ross Sea of Antarctica. Communications Earth & Environment, 6(1), 921, https://doi.org/10.1038/s43247-025-02878-x
How to cite: Preine, J., Tominaga, M., Panter, K., Bangs, N., Pecher, I., and Diviacco, P.: Fault-controlled submarine and subglacial explosive volcanism along the Terror Rift, Antarctica: New insights from integrated multichannel seismic data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1955, 2026.
The western part of the Ross Sea embayment of Antarctica is a showcase of the interaction among Earth systems at various time and spatial scales marked by volcanic and magmatic emergences. We present a comprehensive investigation on the distribution and the vicinity of volcanic constructs within the western Ross Sea seafloor, which likely interacted with multiple advances and retreats of continental icesheets over time, using data acquired during the NBP25-01 Expedition(February-April 2025) on RVIB Nathaniel B. Palmer. Our study area is delimited by Ross Ice Shelf and Ross Island on the south and the Pacific to the north and is bordered by Transantarctic Mountains to the west and the Victoria Land Basin to the east with Terror Rift, currently an active magmatic rift under thick sediments, in between. Our expedition provides a refined view of the seafloor composed of widespread underwater volcanism within the Terror Rift Volcanic Field (TRVF) that include several polygenetic volcanic edifices, some of which appear to be highly eroded by ice sheets. Numerous monogenic volcanic cones were also identified, including a remarkable morphological type of flat-topped seamounts that are found throughout the western Ross Sea. They were mapped, sampled, and imaged, all of which provide evidence of varying amounts of erosion, that we suggest is caused by their interaction with grounded or pinned icesheets/shelves in past, including possible interaction during eruption of submarine volcanoes (i.e. glaciovolcanism). To better understand the lithosphere evolution with widespread volcanism that comprise the TRVF, including within the modern rift itself, we also present new heat flow measurements made during the NBP2501 Expedition via a violin-bow type heat flow probe. We conducted a total of 28 heat flow measurements along and across Terror Rift, from the Drygalski Ice Tongue to offshore Ross Island, which is twice the number of measurements taken by previous expeditions in total. The measured heat flow is ~30 and ~5 mW/m2 higher than that of previously modeled in the northern and southern part of the basin, respectively. Conductive thermal modeling of volcanism along faults cannot fully explain the heat flow pattern of 90-110 mW/m2 across the Terror Rift. Whereas hydrothermal cooling can effectively extract heat from young volcanism, as evidenced by imagery of and recovery of thermally altered materials, fluid circulation alone cannot simulate the heat flow pattern. The seafloor may experience a near-pure conductive heating condition during the Last Glacial Maximum as been suggested by our seafloor morphology characterization above. However,the high heat flow (at average of 100 mW/m2) would melt the base of thick ice at a rate of ~1 mm/yr, creating a nearly equivalent condition as in an open ocean setting. We therefore suggest the observed heat flow pattern is overwhelmingly reflecting a broader tectonic process, likely associated with a steeper geotherm through the lithosphere while minimizing the “icy blanket” effect in the Ross Sea, implying a shallower lithosphere-asthenosphere boundary at 45-55 km below seafloor across the Terror rift. These findings are critical to models for lithospheric rigidity and isostatic response to glacial cyclicity.
How to cite: Wu, J.-N., Tominaga, M., Panter, K. S., Berthod, C., Preine, J., Neumann, F., Tivey, M., and Negrete-Aranda, R.: Submarine volcanism interacted with icesheets in the western Ross Sea, Antarctica , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15330, 2026.
Glaciers have been retreating globally for more than 100 years. In Iceland, where glaciers cover some of the most active volcanoes, this is causing rapid regional uplift (Glacio-Isostatic Adjustment - GIA). This process has been very prominent over the last three decades, resulting in uplift similar to 4 cm/yr in the volcanic zone covered by Vatnajökull glacier, monitored by continuous GNSS stations. This includes the subglacial central volcano Grímsvötn, in the western part of Vatnajökull, one of the most active volcanoes in Iceland. Gravity surveys are a powerful geophysical tool for investigating surface and subsurface geological processes based on variations in the Earth's gravitational field. Many gravity base stations were established in Iceland in 1968-1971, including in the proximity of the retreating Vatnajökull. In this study, data from several gravity surveys conducted on Vatnajökull over the last 30+ years is used, to detect absolute gravity changes. These surveys include repeated ties of the base station established at Grímsfjall in 1971, a nunatak on the southeastern rim of the Grímsvötn caldera, with the other base stations. As Grímsvötn is a highly dynamic ice-covered volcano, the gravity data series is influenced by several local processes. These are (1) changes in ice cover and ice thickness at the volcano caused by variations in geothermal activity, (2) changes in bedrock topography caused by volcanic eruptions in 1998, 2004 and 2011, (3) variations in water level in the subglacial lake in the Grímsvötn caldera, and (4) potentially variations in groundwater level in the volcanic edifice. In addition, the gravity is affected by (5) inflation and subsidence associated with magma accumulation and the eruptions. Processes (1), (2), (3) and (5) can be constrained as well as the regional gravity effect caused by uplift due to GIA. The results show large variations with time in the value of g (>0.5 mGal) at Grímsfjall over the last 30 years. While process (2) is too small to register, processes (1) and (3) are very prominent, superimposed on the GIA effect. This contrasts sharply with more regular effects of GIA, seen at the base stations by the edge of the glacier.
How to cite: Völkel, H., Gudmundsson, M. T., Högnadóttir, T., and Magnússon, E.: Changes in absolute gravity at base stations in ice-covered volcanic areas – the combined effects of isostatic rebound, ice cover and volcanism at Grímsvötn, Iceland, 1971-2025 , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1101, https://doi.org/10.5194/egusphere-egu26-1101, 2026.
Several eruptions at glacierized volcanoes have been witnessed during the 20th and 21st centuries. However, most of the published studies of these eruptions have focused on understanding the volcanic products or the hazards generated by volcano-ice interactions. Much less attention has been put into analyzing the effects on the glaciers. During the 2010 summit eruption of Eyjafjallajökull (Iceland) three different areas of its glacier were affected in distinct ways: (i) The summit caldera by the formation of eruption vents—the main one active for almost six weeks; (ii) the southern flank by a short-lived (one day) eruption fissure; and (iii) the outlet glacier Gígjökull by (subglacial) lava propagation over more than two weeks. Lava accumulation started subglacially in the caldera and eventually became subaerial while progressing northwards, finally reaching a length of more than three km.
Here we study how the ice cap has evolved after the eruption and how individual areas have changed with time. We use elevation data obtained from Pléiades, SPOT5, LiDAR scans, and overflights to calculate elevation and volume changes over varying time periods. Aerial photographs and on-site investigations helped documenting visual changes. Lastly, we used Ground Penetrating Radar (GPR) to map the depth to the 2010 tephra layer in the accumulation area and to the volcanic bedrock.
While signs of the eruption on the southern flank have completely vanished, the areas in the caldera have not fully recovered. This is most notable in the northern part of the caldera where subglacial lava emplacement started. However, snow accumulation and thus gain in elevation in most of the impacted areas started quickly after the eruption ended. From August 2010 to August 2014 the area of the main vent showed an elevation increase of more than 80 m. A similar increase was visible on top of the lava pile towards the north. Gígjökull also started to recover, although the glacier front has been alternating between advance and retreat—similar to the pre-eruption time. Volume change and area calculations reveal that the ice cap overall is shrinking. The glacier covered an area of 72.3 km2 in 2010 and decreased to 63.5 km2 in 2024, with an average elevation change of -8.3 m. However, the caldera and Gígjökull do not follow this trend and showed a persistent volume increase over various time periods from 2010 to 2024, corresponding to an average elevation change of +13.4 m. A potential explanation for the fast recovery of the summit area is the positive feedback effect on the mass balance. The depressions formed by the eruption acted as traps for drifting snow in winter, resulting in a local thickening rate far exceeding the average winter accumulation. Sporadic geothermal activity has also been detected. This includes the re-emergence of a minor cauldron in October 2024 which was first observed in 2012.
How to cite: Sobolewski, L., Gudmundsson, M. T., Magnússon, E., Belart, J. M., Walter, T. R., Edwards, B. R., Sah, K. M., Kochtitzky, W., and Sturkell, E.: Long-term impacts of volcanic eruptions on glacier dynamics – a case study of the 2010 summit eruption of Eyjafjallajökull, Iceland, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11940, 2026.
Some of the most active volcanoes in Iceland are ice-covered due to the northerly latitude of the island. The last three decades have been very active, with six eruptions occurring in glaciers. These were the Gjálp eruption of 1996, Grímsvötn in 1998, 2004 and 2011, Eyjafjallajökull in 2010, and accompanying the large Holuhraun eruption in 2014-15, and the associated subsidence of the Bárðarbunga caldera a few very minor eruptions occurred under the glacier. A large number of photos of these events provide unique documentation of glaciovolcanism. At the Institute of Earth Sciences, University of Iceland, monitoring of volcanic eruptions, mostly from aircraft, has been done in a systematic way since 1996. The photos from the eruptions of Gjálp in 1996 and Grímsvötn in 1998 were taken on film and exist as slides. From 2000 onwards, photos are mostly digital. EPOS (European Plate Observing System) is a multidisciplinary, distributed research infrastructure that facilitates the integrated use of data, data products, and facilities from the solid Earth science community in Europe. Under EPOS, an Icelandic infrastructure project, EPOS-Iceland, has as one of its aims to create a data base of photos from eruptions in Iceland. This project is led by the Iceland Meteorological Office, with participation of the Institute of Earth Sciences, University of Iceland, the Iceland GeoSurvey (ISOR) and the Natural Science Institute of Iceland. The images will include detailed metadata, including the relevant data on event, location, time, type of event and phenomena observed. The EPOS data bases are set up using the FARE principle and the images should therefore be available for future research by those interested in exploiting the data. The photos used display large scale ice cauldron formation under thick ice (Gjálp 1996), major uplift of a subglacial lake in Grímsvötn caldera associated with this eruption and a major jökuhlaup carrying large ice bergs and destroying bridges. In the Grímsvötn eruptions (1998, 2004 and 2011) large ice cauldrons with vertical walls developed around the eruption sites and large scale tephra deposition occurred. In the Eyjafjallajökull eruption (2010), both ice cauldron formation and the propagation of a subglacial lava is documented. During Bárðarbunga-Holuhraun in 2014-15, the photos document subtle signs of very small eruptions and the 65 m subsidence of the Bárðarbunga caldera, filled with 700-800 m of ice.
How to cite: Högnadóttir, T., Gudmundsson, M. T., and Sigurdardóttir, Þ. E. L.: Photographs of active glaciovolcanism in Iceland over the last three decades - use in research and sharing via EPOS, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14334, 2026.
In Iceland, hydrothermal alteration in volcanic rocks results from the interaction of heat, fluids, and surface processes under changing environmental conditions. In particular, the Námafjall geothermal area in northern Iceland hosts active fumaroles, mud pools, and extensive acid–sulphate alteration, resulting in widespread surface mineral distributions. Point-based sampling captures mineralogy at a single location but misses spatial variability, while broader-scale observations do not provide detailed spectral features. To address this, this study evaluates how mineralogical information changes when moving from laboratory measurements to field-based and spaceborne hyperspectral observations, and how these datasets can be linked in an active geothermal environment.
Here, we interpret mineralogy based on integrating laboratory X-ray diffractometer analyses, ASD spectroscopy, laboratory hyperspectral imaging using a SPECIM camera, field-based hyperspectral imaging with HySpex camera, and spaceborne hyperspectral observations from EnMAP. Laboratory analyses identify mineral phases by their diagnostic spectral features, while field-based hyperspectral imaging captures intermediate-scale variability. Spaceborne imagery provides broader-scale mineralogical information but covers only a small area (~30 pixels, each 30 m by 30 m). Each pixel contains mixed surface materials, causing spectral mixing and limiting extraction of distinct minerals at this scale. Hence, to improve mineral identification at field and spaceborne scales, wavelength maps in the SWIR region (2100–2400 nm) were generated to analyse the position of the deepest absorption features across the surface. It helps identify areas where mineralogical information is most likely to be preserved in both field and satellite data.
Based on field observations and the known geology, hydrothermal mineral assemblages at Námafjall are expected to include clays, zeolites, carbonates, sulphates, and native sulphur. But from the preliminary laboratory results of this study, clay minerals and native sulphur were detected in specific samples, while sulphates were not detected. Native sulphur was also observed in field-based hyperspectral data; however, high surface moisture and coarse spatial resolution impacted identification of other mineral classes. To further address uncertainties, spectra will be interpreted after applying linear spectral unmixing and by comparing with spectral libraries. Based on the resulting set of possible minerals at each scale, mineral classification maps will be produced to enable consistent visual comparison of mineral distributions across the three scales.
How to cite: Ravi, A., Alsemgeest, J., Bakker, W., Werff, H. V. D., and Ruitenbeek, F. V.: Multi-scale Hyperspectral analysis of mineral distribution in active geothermal field - Námafjall, Iceland, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10928, 2026.
Due to its northerly latitude, about 10% of Iceland is covered by glaciers and a substantial part of the most active volcanoes are ice covered. As a result, volcano-ice interaction in various forms is very common in Iceland. Steep-sided mountains (elongated ridges and tuyas) formed in volcanic eruptions during the repeated Pleistocene glaciations dominate the landscape in many parts of the volcanic zones. Over the last 30 years, when active monitoring has taken place, six eruptions, ranging in composition from basalt to trachyte have occurred in glaciers in Iceland. The 1996 Gjálp eruption within the Vatnajökull glacier occurred where the initial thickness was 600-750 meters. As a result, the bulk of the activity was fully subglacial, ice flow into the depressions formed was substantial, and the observed subaerial phase was relatively modest. The eruptions in Grímsvötn (1998, 2004 and 2011) and Eyjafjallajökull (2010) occurred where ice was 0-200 m thick, forming ice cauldrons with vertical walls and ice flow played a very minor role, and explosive activity, mostly phreatomagmatic, was dominant. The third type of activity was observed above the NE-wards propagating dyke from the subsiding Bardarbunga caldera, formed in the days prior to the onset of the large Holuhraun eruption in 2014. These minor leaks of magma caused small, fully subglacial eruptions where the ice was 300-500 m thick. Ice melting was of the order of 1-10 million m3 in the smallest events (2014), while 3 km3 melted during the Gjálp 1996 eruption, with another 1 km3 melted in the following months. That eruption formed a 6 km long, up to 500 m high ridge under the glacier. Ice melting caused jökulhlaups in some of the eruptions. The one following the Gjálp 1996 eruption was by far the largest. It had a peak discharge of 40,000-50,000 m3/s as 3.5 km3 of meltwater were released from the subglacial Grímsvötn caldera lake, where it had accumulated over five weeks. The jökulhlaups observed had some impact on the glaciers above the meltwater path. However, this change was relatively minor and did not cause major disruption. For the largest events some breaking up of the glacier snout occurred, resulting in large ice blocks being carried by the floodwater. Considerably larger events have occurred in the recent past, notably the eruption of Katla in 1918. The very powerful phreatomagmatic early part of that eruption, starting under initially 300-400 m thick ice, produced over 100,000 m3/s of meltwater and deposited several hundred million m3 of water-transported tephra on the Mýrdalssandur outwash plain.
How to cite: Gudmundsson, M. T., Högnadóttir, T., Reynolds, H. I., Cole, R., Sobolewski, L., Magnússon, E., and Pálsson, F.: Glaciovolcanism in Iceland: Observations of frequent eruptions over the last three decades, styles of activity, influence of ice thickness and impact on the glaciers, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12847, 2026.
Numerous jökulhlaups have rushed down the river Jökulsá á Fjöllum in NE-Iceland during the Holocene. Some of these fall under the category of catastrophic floods that carved out the present-day Jökulsá canyon, over 100 km north of the present-day Vatnajökull.
Volcanic glass in sedimentary beds deposited by 16 jökulhlaups (glacial floods) in river Jökulsá á Fjöllum, between 6.3 and 4.1 ka ago, correlates the jökulhlaups to three volcanic systems beneath Vatnajökull ice cap. Chemical characteristics of Bárðarbunga volcanic system dominate in 12 sedimentary beds, those of Grímsvötn and Kverkfjöll in one bed each, two remain unsolved.
The characteristics of the Bárðarbunga glass in the jökulhlaup sediments are mostly low TiO2 and high MgO (TiO2 <1.6, MgO >7.3 w%). Seventeen basaltic “Low-Ti” tephra layers from Bárdarbunga have been identified in soils in N-Iceland from this same period. Grain characteristics of the tephra indicate phreatomagmatic origin. Dispersal maps confirm source area below northwest Vatnajökull and tephra volume (bulk) of the order of 1 km3 for the largest layers.
The mid-Holocene floods confirm the existence of glaciers on Bárðarbunga, Kverkfjöll, and Grímsvötn 6.3 to4.1 ka ago. The magnitude of these jökulhlaups is not well constrained, but apparent cross sections indicate a peak discharge of order 30,000 -100,000 m3/s and likely total volume of some km3. The source areas of these repeated jökulhlaups 6.3 to 4.1 ka ago were most likely the calderas of the central volcanoes, which may have changed in size and form since the mid-Holocene.
Eruptions within the Bárðarbunga caldera are therefore a possible source for 12 of these floods. Bárðarbunga may have hosted a geothermal area and a subglacial caldera lake similar to present day Grímsvötn, which may explain the repeated, apparently similar-magnitude jökulhlaups over this long period.
With recent unrest at the Bárðarbunga volcanic system, including the 2014-2015 Holuhraun eruption with magma drainage and collapse at Bárðarbunga caldera, jökulhlaups in this category must be considered in preparations for future hazards. On its nearly 180 km long course from Vatnajökull to the bay of Axarfjörður, Jökulsá á Fjöllum traverses several habitated and recreational areas. Keeping in mind significantly thicker ice cover at present, potential jökulhlaups larger than the 6.3-4.1 ka floods should also be considered a possibility.
How to cite: Larsen, G., Gudmundsson, M. T., Gudmundsdóttir, E. R., Oladóttir, B. A., and Sigmarsson, O.: Mid-Holocene jökulhlaups in Jökulsá á Fjöllum, NE-Iceland, correlated to eruptions in Bárðarbunga volcano 6.3 to 4.1 ka ago, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13730, 2026.
Quantifying glacier elevation and mass changes is essential for understanding glacier dynamics as well as the interaction between volcanic activity and ice cover. This study investigates glacier elevation and mass changes within the Klyuchevskaya Volcanic Group (KVG) on the Kamchatka Peninsula using TanDEM-X and SRTM C-band SAR data combined with a differential SAR interferometric approach. Elevation and mass changes are assessed for the period 2000–2020, demonstrating the suitability of TanDEM-X digital elevation models for geodetic glacier analysis in volcanically active environments. Cumulative mass loss 2000-2020 amounts to −0.782 ± 0.058 Gt. For the total glacierized area of 204.15 km², an average elevation change rate of −0.347 ± 0.011 m a⁻¹ is derived, corresponding to a specific mass balance of −295 ± 23 kg m⁻² a⁻¹ for the period 2012-2020, with locally much higher losses. Marked temporal variability is observed, with strongly increased mass loss after 2015/16 (-0.528±0.014 m a-1) coinciding with intensified volcanic activity. Enhanced supraglacial debris cover following frequent and larger eruptions significantly influences glacier mass budgets, as supported by Landsat 8 Normalized Difference Snow Index analyses. Despite the absence of field-based debris thickness measurements, spatial patterns across individual glaciers highlight the critical role of volcanic debris in modulating glacier response.
How to cite: Seehaus, T. and Georg, D.: The impact of volcanic activity on the glaciers of Kamchatka, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3568, 2026.
Volcanoes can affect overlying glaciers through a variety of processes over a spectrum of spatial and temporal scales. The formation or expansion of melt features (e.g., ice cauldrons) within glaciers have been widely reported as a response to subglacial volcanic unrest and pre-eruptive activity. There are, however, far fewer documented examples of the effects that volcanic unrest may have on individual glacier dynamics. Previous studies have identified higher flow velocities of glaciers near volcanoes, and that some glaciers may speed-up in response to precursory volcanic activity. To investigate the prevalence of such dynamic responses and the potential of using these to inform on volcanic hazards, we carried out a global study of glaciers near volcanoes. We used open-source glacier velocity measurements produced from freely accessible images from the Landsat 4-9, Sentinel-1 and Sentinel-2 satellites. We observed a variety of glacier velocity anomalies, some of which can only be explained as volcanically driven. Of note are velocity anomalies associated with jökulhlaups from subglacial geothermal areas in Iceland, as well as glacier speed-ups concurrent to volcanic unrest at Mount Spurr and precursory to a volcanic eruption of Mount Veniaminof in Alaska. Our results demonstrate the feasibility of using free remote sensing products and open-source code to assist with the monitoring of glacierised volcanoes.
How to cite: Unnsteinsson, T., Spagnolo, M., Rea, B., Girona, T., Barr, I., and Mullan, D.: Monitoring glaciers for precursory signs of volcanic activity, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14515, 2026.
Large-scale tectonic fault structures shape many flow paths of modern ice sheets at high-latitude ice dominated continental margins. However, the influence of these structures on glacial pathways on the East Antarctic continental margin, as well as the impact of glacially induced tectonic movements, are under-investigated. Here we present the first results of tectonic analysis of fault structures in seismic reflection data from Vincennes Bay off Knox Coast, East Antarctica. The Vincennes Bay continental shelf exhibits four distinct phases of faulting since Gondwana break-up between Australia and Antarctica. The first and second phases are expressed as positive flower structures oriented roughly northwest to southeast. These align with the offshore Vincennes Fracture Zone and magnetics data indicate a dextral strike-slip fault zone with a local transpressive character. There are at least four distinct similarly oriented flower structures occurring at different times, three prior to Cretaceous continental break-up and at least one after Australia fully separated from East Antarctica. The orientation of flower structures on the continental shelf suggests a continuation through the Vanderford Glacial Trough, indicating that this fault zone provided an easily erodible pathway for pre-glacial fluvial activity followed by glacial ice flow. Faults produced by later tectonic phases are oriented roughly east to west showing signs of flexural stresses, indicating a different stress regime than previous tectonic events. These later phases were induced by glacial loading and unloading of an advancing and retreating East Antarctic Ice Sheet (EAIS) during its early establishment in the region (about 27-14 Ma) and during grounding line oscillations under full glacial conditions (later than 14 Ma). The relationship between fault zones and glacial troughs illustrates how pre-glacial tectonic processes influence past and modern ice flow configurations. Ice loading and unloading on the continental shelf due to the establishment of the EAIS and its grounding line oscillations aid the reconstructions of EAIS ice streams during the Cenozoic.
How to cite: Mühlberger-Krause, T., Hochmuth, K., Gohl, K., Whittaker, J., Halpin, J., Leitchenkov, G., Tobisch, C. A., and Krastel, S.: How Gondwana break-up influences East Antarctic ice flow and regional ice load tectonics – insights from the Knox Coast, East Antarctica , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8948, 2026.
While subaerial thermal springs are common around Greenland’s ice-free periphery, such springs have not yet been documented beneath the ice that covers ~85% of Greenland. Here, we present evidence that presumptive subglacial thermal springs play a critical role in maintaining two major subglacial lakes beneath Flade Isblink, in Northeast Greenland. The thermogenesis of these subglacial thermal springs may be hitherto undocumented recent volcanism, or exothermic weathering. This latter thermogenesis would be associated with the inflow of oxygenated meltwater and oceanic water into a tectonically fractured, pyrite-rich, carbonaceous mudstone basement beneath the ice cap. We estimate that these springs deliver localized basal heat flows of >960 mW m–2 beneath both lakes. This is extremely elevated relative to background geothermal flow. This heat flow maintains locally thawed ice-bed interfaces at the subglacial lakes, in an otherwise frozen-bedded ice cap. Given the sensitivity of ice flow to basal thermal state, subglacial thermal springs can therefore have a potent influence on local ice dynamics.
How to cite: Bendix Nielsen, E., Colgan, W., Aaby Kruse, M., Chartrand, A. M., Løkkegaard, A., Rutishauser, A., Rosa, D., Svennevig, K., MacGregor, J. A., Djurhuus Poulsen, M., Kühl, M., and Abbas Khan, S.: Extreme basal heat flow and presumptive subglacial thermal springs in Northeast Greenland, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22547, 2026.
Insight into the past geological evolution of Mars is limited by our ability to view the Martian subsurface. Therefore, our understanding of geological evolution relies primarily on remotely sensed observations, which mainly constrain the latest stages of the geological processes responsible for shaping the observed landforms. However, in specific cases, certain surficial landforms can reveal aspects of the geological history of particular regions. On Earth, when lava encounters (near)surficial ice deposits or water, it triggers explosive phreatomagmatic activity, forming rootless cones that serve as evidence of lava-water interaction. Such landforms indicate that waterlogged or ice deposits were present at the time of the volcanic activity. Although volcanism has played a dominant role in shaping the Tharsis surface, and despite the presence of cold-based tropical glaciers on the flanks of its major volcanoes, there is little evidence of lava-water interactions. To address this, through detailed analysis of Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) surface imagery, coupled with stereo-pair–derived topographic data, we report the presence of rootless volcanic cones located south and southeast of Ascraeus Mons. Directly atop the individual lava flows dated to younger than 215 Ma, we identified >2,000 conical edifices that form a morphologically homogenous population with an average basal width of 96 ± 31 m (1 standard deviation; SD; n = 249) and a crater width of 43 ± 18 m (1 SD; n = 207). Digital elevation models (DEMs) indicate that these edifices have an average height of 3.8 ± 2.0 m (1 SD; n = 178). Their morphological parameters and structural relationship with the hosting lava flows closely resemble both terrestrial and Martian rootless constructs. Furthermore, their exclusive superposition on individual lava flows indicates that their formation was strictly controlled by, and limited to, lava flow emplacement. This, in turn, enables a more accurate spatiotemporal reconstruction of ice distribution at the time of volcanic activity, providing insight not only into the geological evolution of this particular region but also into the obliquity state of Mars during that period. Moreover, the presence of spectrally-identified monohydrated sulfates suggests past hydrothermal circulation driven by lava-water interactions. Consequently, we propose that these young, small landforms, interpreted as rootless cones, provide valuable constraints for reconstructing the Martian paleoclimate by delineating former ice-rich zones. They should also be considered high-priority targets in future life-detection missions, as they satisfy key habitability criteria.
This project was conducted within the framework of the MARIVEL project, funded by the National Science Centre of Poland (grant no. 2024/53/B/ST10/00488).
How to cite: Pieterek, B. and Jones, T.: When lava meets ice: Explosive eruptions in the late Amazonian in Tharsis, Mars, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2006, 2026.
