The oft-quoted statistic that 1% of the world’s glaciers are surge-type may suggest that surging is a rare, anomalous phenomenon. Among some populations of glaciers, however, surge-type glaciers are in the majority. For example, for glaciers over 16 km in length in Svalbard and Iceland over half have recorded surges. Surge-type glaciers are widespread in a broad arc stretching from Alaska to Novaya Zemlya (the Arctic Ring) and in many parts of High Mountain Asia. This distribution is defined by ranges of temperature and precipitation within which many glaciers cannot achieve stable steady states, as predicted by Enthalpy Balance Theory. 

Climatic controls on surging behaviour imply that the distribution of surge-type glaciers will shift in response to changes in temperature and/or precipitation. For example, the Arctic Ring may have been located south of its current position during some colder periods of the Quaternary. This was likely the case for Younger Dryas glaciers in Scotland. Reconstructions of palaeotemperature and palaeoprecipitation indicate that the Highlands and Islands of Scotland fell within the optimal climatic envelope for surging during the Younger Dryas. Examination of the landform record supports the conjecture that surge-type glaciers were widespread, including many outlet glaciers of the West Highland Icefield and smaller icecaps on the islands. 

Recognition of palaeosurges is important, because glacier reconstructions are commonly used as climatic proxies based on the assumption that glacier geometries represent stable steady states. Landsystem models are useful in this regard, provided they are applied flexibly with due consideration for local conditions and preservation biases. Systematic use of landsystem models and other tools may reveal other former clusters of surge-type glaciers in mid-latitude mountain regions.

How to cite: Benn, D.: Glacier Surges Past and Present: Theory, Current Distribution and the Landform Record, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17112, https://doi.org/10.5194/egusphere-egu23-17112, 2023.

It is estimated that the impact of global warming in polar regions manifests double as much as other geographical provinces around the world, and in Svalbard particularly, reaches 7 times of it. Clearly, the most observable impact of these changes considers thinning of an ice-cover and glaciers retreat, which is reported as a ‘glacier mass balance’. The glacier submarine moraines studies in Svalbard, indicate that the small ‘glaciation epoch’ ended around 1909. That means that for the last several decades we observe a continuous retreat of the glaciers. It is estimated that since 1960s there is an overall negative glacier mass balance around the whole archipelago of Svalbard and in present, the total mass loss varies between 5 and 10 Gt/year. Also, recent studies report that the glacier retreat rates increase yearly, where in some areas can reach even over 100 meters per year.

Our filedwork in 2021 and 2022 in Kaffiøyra, western Svalbard, shows that the glaciers retreat exposes new vast areas that had never been studied before. Since the glaciers age are between 20,000-30,000 years old, we are able to map for the first time the tectonic setting of the newly exposed areas. A continues retreat of the Glacier Aavatsmark in northern Kaffiøyra exposes a contact between formations of the Paleogene and Neoproterozoic, which is a boundary of a tectonic Forlandsunded Graben and Caledonian basement (Hecla Hoek sucession) of the Eurekan orogeny. In here, newly exposed outcrops reveal highly deformed and sheared phyllite and schist formations which indicate large boundary of a transpression and following transtension phases of the deformation of the metamorphic complex characterized by metamorphic metasandstones, quartzites and serpentinites of the Neroproterozic, mainly- Late Cryogenian and Ediacaran. We also indicate clear strike-slip components along this boundary.

However, in our study area we have found that a glacier surge greatly aids exposition of the new outcrops especially in the glacier forefield regions. The surge is an abnormal occurrence where an entire glacier suddenly accelerates its movement up to several meters per day. It is associated with a disbalance of a glacier mass at the ablation zone versus accumulation zone. A continuous reduction of a glacier mass at an ablation and increase of sub-glacier waters can trigger a ‘glacier surge’, where velocity can reach up to 1000 times comparing to quiescent time and can last from months to years. In 2013 a massive surge of a glacier Aavatsmark yielded glacier movement up to 5 meters per day and lasted for two years. Because of this sudden increase of the ice mass movement the front of the glacier toe (terminus) served as a ‘shovelling tool’ for the moraines in the forefield areas. This unusual occurrence cleaned vast areas of new outcrops of the boundary of the Forlandsunded Graben that have never been mapped before. With the support by UAV 3D mapping along the graben boundary, we have put new tectonic features as well as structural measurements of the area.

How to cite: Giletycz, S. J., Cai, F.-Y., Kuo-Chen, H., Sobota, I., Greń, K., and Guan, Z.-K.: Glaciers surge ‘shovels’ forefield moraines for geological surveys, example from northern Kaffiøyra, Svalbard, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-903, https://doi.org/10.5194/egusphere-egu23-903, 2023.

Both modern and palaeo ice streams experience shut down which has critical implications for their mass balance and influence on relative sea level rise. Reconstructions of palaeo-ice streams have mainly focused on their phase of active flow but less is understood of their shutdown and style of deglaciation. Mapping of streamlined subglacial bedforms (SSBs), including drumlins and mega scale glacial lineations (MSGLs), in NE-Iceland reveals cross-cutting flow-sets of palaeo-ice streams within the Iceland Ice Sheet (IIS) during and following the Last Glacial Maximum (LGM). Here we map geometrical ridges (linear and reticular) in the Bakkaflói and Þistilfjörður areas and combine the morphological data with sedimentological analyses to increase our understanding of the dynamics of the IIS in NE-Iceland. We interpret the ridges as crevasse-squeeze ridges (CSRs), based on their interconnected network, primary orientation transverse and/or oblique to former ice flow, and internal composition of homogenous subglacial till. In both areas, the CSRs are superimposed on the SSBs, indicating that they post-date the formation of the SSBs and signify the waning stage of ice streaming associated with the readvance of the IIS during the Younger Dryas period. The preservation of the CSRs suggests ice stagnation following the readvance and ice stream shutdown. The morphological variance of the CSRs between the flow-sets may indicate different spatial-setting within the ice streams; the linear CSRs in Bakkaflói formed further upstream (dominated by extensional forces parallel to ice flow). Comparatively, the reticular CSRs in Þistilfjörður are more characteristic of the down-ice region (effected by mixed mode of transverse and longitudinal forces), proximal to the ice margin or piedmont. Future research reconstructing past glacial behaviour and ice dynamics would benefit from high-resolution bathymetric data from the adjoining shelf as well as enhanced geochronological constraints.

How to cite: Aradóttir, N., Benediktsson, Í. Ö., Ingólfsson, Ó., Farnsworth, W., and Brynjólfsson, S.: Geomorphic evidence of ice stream shut down within the Iceland Ice Sheet, northeast Iceland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8068, https://doi.org/10.5194/egusphere-egu23-8068, 2023.

Unknown basal characteristics limit our ability to simulate the subglacial hydrology of rapidly thinning contemporary ice sheets. Sediment-based landforms deposited beneath former ice sheets can provide crucial information about basal hydrology during rapid ice loss. Murtoos—low-relief (5–10 m) features with a distinct triangular morphology—have been identified throughout Finland and Sweden within terrain formerly occupied by the Fennoscandian Ice Sheet (FIS). The depositional environment and formation of murtoos are not yet predicted by existing models of subglacial landforms. Excavations have revealed that, distally, murtoos are composed of alternating facies of heterogeneous diamicton, with strong fabrics interbedded with sorted gravelly and sandy sediment. Proximally, murtoos exhibit glaciofluvial deposits, such as current ripples, transitional cross-bedding, and antidunal sinusoidal laminations reflecting alternating lower and upper flow regimes. Additionally, regional mapping has revealed a spatial association of murtoos with other meltwater features and a characteristic presence no closer than 40–60 km from the FIS margin at ~12 ka. Collectively, these indicate that murtoo deposition is accompanied by rapid increases in meltwater discharge—potentially within a single melt season—and is associated with areas of low effective pressure and the spatial onset of channelised drainage systems.

We used the Ice Sheet System Model (ISSM) implementation of the Glacier Drainage System (GlaDS) model to investigate murtoo genesis beneath the FIS. We parametrised GlaDS using digital elevation models (25 m/pixel) and estimations of ice surface elevation given by viscously relaxing initially parabolic ice profiles. Transient surface melt was introduced to a stable hydrological system over 10,000 days via moulins randomly distributed throughout the model domain. Moulin discharge rates were calculated using a positive degree day scheme forced by a depressed contemporary climate. Sensitivity testing was carried out for several poorly constrained parameters in GlaDS, as well as for the initial ice geometry and climatic inputs. 

We first applied GlaDS to a specific corridor of ice-flow within the relatively low-relief Finnish Lake District, where murtoos are densely concentrated, and then to a high-relief area of the Scandinavian Mountains towards which the FIS retreated prior to its demise. Murtoo density, as well as their gemorphic characteristics, was compared to the modelled sheet thickness, channel cross-sectional area, water pressure, and discharge rates through both the distributed and channelised system. Our modelling reproduces the hypothesised area of low effective pressure 40–60 km from the margin and supports the hypothesis that murtoos form in highly dynamic areas of the basal water system. This work highlights the value of applying GlaDS to glaciated regions in which hydrological outputs can be compared directly to geomorphological evidence. 

How to cite: Hepburn, A., Dow, C., Ojala, A., Mäkinen, J., Elina, A., Palmu, J.-P., Hovikoski, J., and Kajuutti, K.: Landscape generation by subglacial hydrology beneath the Fennoscandian Ice Sheet, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7408, https://doi.org/10.5194/egusphere-egu23-7408, 2023.

We present new insights into the ice flow dynamics of the Last Glacial Maximum (LGM) Rhine glacier based on a comprehensive inventory of glacially streamlined bedforms. High-resolution LiDAR data was used to map ice-marginal moraines and more than 2500 subglacial landforms located in the ~6000 km²-sized footprint of the former piedmont lobe. Orientation and morphometry of mapped bedforms were subsequently used to deduce paleo ice flow lines. Most of the subglacial landforms in the dataset are drumlins, but glacial lineations and subglacial ribs (Rogen/ribbed moraines) are also present in the study area. Streamlined bedforms predominantly occur in fields internal to the frontal moraine set of the inner (Stein am Rhein ice margin) of two LGM ice marginal complexes (Kamleitner et al., 2023). We interpret these landforms to have been shaped isochronously during the late LGM readvance (Kamleitner et al., 2023; Schreiner, 1992) to and the active stabilization at the Stein am Rhein ice marginal position. Deviating drumlin orientations (e.g. cross-cutting relationships) are rare within the Stein am Rhein flow set, supporting the hypothesis of contemporaneous formation. Bedform orientations of this flow set are the basis for inferring the ice flow patterns during the Stein am Rhein stadial. Continuous fields of flow are interpolated by applying the recently presented kriging approach of Ng and Hughes (2019). The reconstructed directions show radial ice flow emanating from the mouth of the confined Alpenrhein Valley that fans out towards the Stein am Rhein frontal moraines. Flow lines converge due to compression in narrow valley sections and diverge around topographic highs. Basal ice flow during the late LGM Stein am Rhein readvance was strongly controlled by topography. Derived paleo flow lines are combined with information from bedform elongation that allows to confine potential areas of relatively fast flowing ice. We find these to largely overlap with known overdeepenings, in line with predictions from numerical simulations (Cohen et al., 2018).

How to cite: Kamleitner, S., Ivy-Ochs, S., Salcher, B., and Reitner, J. M.: Subglacial landforms reveal basal ice flow patterns of the Last Glacial Maximum Rhine glacier, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3672, https://doi.org/10.5194/egusphere-egu23-3672, 2023.

During the Last Glacial Maximum (LGM), large glacier tongues reached far into the alpine foreland and formed piedmont lobes. Common deposits are moraine “amphitheatres” directly connected to glaciofluvial deposits, which are both suitable for (direct) age dating. Over much of the Alpine realm, great efforts have been made to constrain the chronology of the LGM, yet in the eastern part, significant gaps exist, and absolute dates for glacial features are missing. Due to a gradual eastward change in terms of precipitation, moisture, and topography, glaciers did not advance as far in the eastern Alps and terminated in narrow inneralpine valleys. Evidence of their extent is therefore sparse and their deposits were mostly cannibalised by later erosional and depositional processes. Nevertheless, remnant terminal moraines from the Enns and Mur glaciers (mainly fed by the Niedere Tauern in the Central Alps) remain. These deposits contain blocks that can be dated with cosmogenic beryllium and aluminium surface exposure dating.

For cosmogenic dating, two sites were investigated as follows. The Enns glacier developed north of the Niedere Tauern mountain range and one of its terminal tongues ended at Buchauer Saddle, where a terminal moraine complex is preserved. The moraine ridges reach a few tens of meters in height and contain mostly blocks of carbonate, with some quartz-containing blocks also present. All dated blocks are Palaeozoic quartz conglomerates/breccias, which crop out roughly 25 km upvalley.

The ice masses of the Mur glacier accumulated south of the Niedere Tauern mountain range in the Mur valley. The glacier was divided into several tongues, one of them terminating near Pöls, where the most prominent moraine of the Mur glacier is preserved. It consists of a diamicton with a silty to clayey matrix and few components of pegmatite gneiss, amphibolite and other crystalline rocks. Datable blocks consist of coarse-grained pegmatite gneiss.

Based on mapping relationships, the spatial context of the both moraine complexes suggest their deposition during the LGM. In this contribution, we will explore this hypothesis so far developed on the basis of field relations by presenting preliminary exposure ages of these landforms.

How to cite: Griesmeier, G. E. U., Braumann, S. M., Reitner, J. M., Neuhuber, S. M., Le Heron, D. P., Marchhart, O., and Wieser, A.: Filling a major gap in the LGM chronology of the Eastern Alps: New evidence from Enns and Mur glaciers (Austria), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5525, https://doi.org/10.5194/egusphere-egu23-5525, 2023.

Over the last two decades the importance of the Andean cryosphere, particularly as water resource, has been recognized in both the scientific literature and the public sphere. However, in contrast to the European Alps, lack of field studies and limited knowledge regarding long-term cryosphere evolution has precluded basic knowledge for water-resource management and planning, particularly in the Andes of central Chile, a region that has been experiencing accelerated warming and a dramatic drought spell.

Using detailed glacial geomorphological mapping as well as new geochronologic and geophysical data we unravel the ice evolution in four Andean basins: Río Limarí (31° S), Río Aconcagua (32° S), Río Maipo (33° S), and Río Rapel (34° S). The Andes of central Chile hide a striking mosaic of Quaternary landforms where climate, cryosphere, and tectonics converge. The findings from our analysis suggest glacier advances during the pre-last glacial period and the Last Glacial Maximum (LGM, ~26–17 ka), between 9–12 ka, ~2700 a cal BP, ~850 a cal BP, and ~600 years ago. Geomorphological evidence and geochronological data suggest at least two glacier advances to nearly the same extent, first by the 13th to 16th centuries and then by the early to mid-19th century. Since then, a gradual pattern of distinct moraine ridges as observed in several catchments denotes a rather active and gradual ice demise. A larger glacier extension than today is also documented during the first half of the 20th century.

Finally, we discuss ages and their paleoclimate implications in the light of previous work in the region. Glacier chronologies in the southern mid-latitudes are suitable to track past latitudinal variability of the southern westerly winds (SWW) through the last glacial period and into the Holocene. For the latest Holocene, we note net humid and cold atmospheric conditions in central Chile between the 13th century and the mid-19th century. We conclude with an interhemispheric comparison of glacier chronologies from the Andes and the European Alps.

How to cite: Nussbaumer, S. U., García, J.-L., Gärtner-Roer, I., Fernández, H., Carraha, J., Pérez, F., Tikhomirov, D., and Egli, M.: Long-term response of the mountain cryosphere to climate change – a comparative perspective of the Andes of central Chile and the European Alps, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11762, https://doi.org/10.5194/egusphere-egu23-11762, 2023.

Despite the existence of numerous glaciers on the Mediterranean mountains during the Little Ice Age (LIA), many of these disappeared during the 20^th century. However, periglacial conditions are sustained in the formerly glaciated alpine zones, preserving relicts of the late Holocene glacial record. The present climate of the Mediterranean mountains is hostile to glaciation and projected climate trends suggest that the Mediterranean cryosphere will be shrinking with immediate impacts on the water budget of the lowlands. Here we show preliminary results of an extensive fieldwork campaign that focuses on the Holocene reconstruction of the climate and alpine critical zone environmental conditions of Mount Olympus (2918 m) in Greece. A well-preserved sequence of late Holocene glacial moraines dating to ⁓2.5 and ⁓0.6 ka BP, respectively, suggest that the small cirque glaciers were geomorphologically active during the LIA, whereas 30 m deep glacial ice found in a perennial ice cave opens a new window of local and regional continuous climate reconstructions. The extensive snowfields of the mid-20^th century have shrunk dramatically but have survived the warmest summers of the 21^st century. Below these perennial snowfields a 15 m thick permafrost layer has been discovered during our campaign through 3 Electrical Resistivity Tomography (ERT) profiles, in a location where the mean annual air temperature (MAAT) of the last 10 years is above 0^oC, but in agreement with permafrost occurrence in other mountains of the Southern Balkan peninsula. The base horizon of postglacial alpine soils overlying glacial till deposited in a glaciokarstic plateau below the summit, appears cryoturbated whereas the soils are characterized by translocation of clay from the upper to the lower horizon. These observations along with occasional early summer soil freeze and subsequent waterlogging, suggest that the periglacial activity on Mount Olympus continues in a rapidly warming Mediterranean environment. However, regional warming and anomalous early summer convective rainfall that has caused a dramatic reduction in the volume of the perennial ice cave deposits and the near extinction of the perennial snowfields (even after winters with very high snow accumulation) over the past 10 years also threatens this periglacial activity. Altogether these observations show the general decreasing trend of the Mediterranean cryosphere and periglacial activity, and they highlight immediate impacts on karstic aquifer water recharge and water availability in the piedmont and coastal zone of Mount Olympus, especially during the summer season when water demand is very high due to agricultural and touristic activities.

How to cite: Styllas, M., Onaca, A., Ardelean, F., Ardelean, A., Perșoiu, A., and Pennis, C.: The last bits of glacial ice and permafrost as remains of the late Holocene Mediterranean glaciations. New discoveries from Mount Olympus periglacial zone, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5728, https://doi.org/10.5194/egusphere-egu23-5728, 2023.

The potential of periglacial landforms in the context of palaeoclimatic interpretation bases on their connection to climate-driven permafrost conditions with both initial formation and continuing activity. The challenge of obtaining reliable numerical age constraints significantly complicates, however, their utilisation for this purpose. One reason is that many periglacial landforms such as patterned ground, rock glaciers, or various solifluction features represent transitional processes of certain duration rather than clearly defined single events. A related high risks of postdepositional disturbance by frost-related processes has also to be taken into account.

Although per se suited for boulder-dominated periglacial landforms, cosmogenic radionuclide dating (CRN) faces the problem that large sample sizes would be required to achieve reliable ages. To overcome this disadvantage, the calibrated-age dating technique of Schmidt-hammer exposure-age dating (SHD) has recently been successfully utilised for obtaining age constraints of such landforms. If robust local or regional SHD age-calibration curves can be established, SHD offers the fundamental advantage of obtaining large sample sizes (hundreds or even thousands of boulders) to overcome the abovementioned limitations of CRN.

Recent studies applying SHD on patterned ground and related features in Jotunheimen (South Norway) revealed that the results obtained not only provide a solid basis for palaeoclimatic interpretation but additionally point towards interesting morphodynamic implications. On Juvflye, a high-altitude plateau typical for Jotunheimen, and its transitional upper slopes to Bøver- and Visdalen around 150 periglacial features has been dated applying a local SHD age-calibration curve. These features included sorted circles, sorted stripes, and boulder-banked solifluction lobes in various morphologies and sizes. They covered an altitudinal range between roughly 1,450 and 1,950 m a.s.l. and several different aspects. 

SHD result show that periglacial activity likely commenced instantly following local deglaciation after the Preboreal Oscillation (PBO, c. 11.45 ka ago). Most important is, however, that all features without exception became definitely inactive prior or latest around the onset of the Holocene Thermal Maximum (HTM, c. 8.0 ka ago). The timing of this stabilisation is surprising because at least high and middle altitudes on Juvflye have been underlain by permafrost during the entire Holocene until today. It seems independent from Holocene fluctuations of the lower limit of permafrost and colder climatic conditions during the Late Holocene and, therefore, challenges also the general application of large patterned ground features as palaeoclimatic indicators for permafrost. Any recent mophodynamic activity on Juvflye is restricted to minor frost-related processes and include micro-scale frost cracking/sorting and solifluction terracettes.

The formation of patterned ground and large-sized boulder-banked solifluction lobes restricted to a limited time period during Early Holocene points morphodynamically towards the conclusion that an occurrence of permafrost per se cannot be seen as the sole factor for their efficient formation and continuous activity. Other factors such as soil moisture availability, active layer thickness, or suitable substrate need to be taken into account. A comparison with micro-scale patterned ground features on recently deglaciated glacier forelands in Jotunheimen strongly suggests that a significant influence of soil moisture alongside micro-climatic factors need to be discussed.

How to cite: Winkler, S.: Early Holocene peak of periglacial activity on Juvflye in Jotunheimen/South Norway revealed by Schmidt-hammer exposure-age dating and its morphodynamic implications, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-936, https://doi.org/10.5194/egusphere-egu23-936, 2023.

Active rock glaciers are among the most common cryospheric landforms in high-altitude mid-latitude mountain ranges. Over both short (years to decades) to long (centuries to millennia) time scales, their activity strongly influences the hydrology and geomorphology of alpine environments. Consequently, rock glaciers reflect paleoclimatic conditions and can be seen as an important player in erosion processes affecting high mountains slopes. Because they represent a visible expression of mountain permafrost and a considerable water reserve in the form of ground ice, rock glaciers are important landforms in the geomorphological and hydrological evolution of mountain systems, particularly in context of climate crisis. However, our understanding of rock glacier dynamics and its evolution at different time scales still need to be improved.

In this study, we present a multi-method approach, including field observations, remote sensing and geochronology, to study the rock glacier system of the Vallon de la Route (Combeynot Massif, western French Alps). Remote sensing images and correlation techniques are used to document the rock glacier movement field on time scales ranging from days to decades. In addition, to estimate displacement over periods ranging from centuries to millennia, we use surface exposure dating with terrestrial cosmogenic nuclides (10Be quartz) on boulder surfaces along the longitudinal line of the rock glacier, targeting different positions from the headwall to the terminus.

The remote sensing analysis processed between 1960 and 2018 agree with the geomorphological observations: the lower two units of the rock glacier are stationary/relict, the transition unit presents small displacement and not over its entire area, and the upper two active units above 2600 m elevation show integrated velocities between 14 and 15 cm a-1.  10Be surface exposure ages are ranging from 13.10 ± 0.51 to 1.88 ± 0.14 ka and their spatial distribution reveals an inverse first-order correlation between surface exposure age and elevation, and a positive correlation with horizontal distance to the headwall. These observations support the hypothesis that boulders fall from the headwall and remain on the surface of the rock glacier as they are transported down the valley. Our results also suggest that the rock glacier is characterized by two major phases of activity. The first phase, beginning around 12 ka, has a 10Be age gradient, following a quiet period between ~6.2 and 3.4 ka prior to the emplacement of the two present-day upper active units. Rock glacier started to be active again by 3.4 ka and still is now above 2600 m a.s.l. These results allow to quantify headwall erosion rates of between 1.0 and 2.5 mm a-1, greater than the watershed-integrated denudation rates estimated on millennial time scales. This suggests that the rock glacier system supports the maintenance of high rock wall erosion by acting as a conveyor of debris and allowing freshly exposed bedrock surfaces to be affected by erosional processes.

How to cite: Lehmann, B., Anderson, R. S., Bodin, X., Cusicanqui, D., Valla, P. G., and Carcaillet, J.: Rock glacier activity over Holocene to modern timescales : insight from a western alp site, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1184, https://doi.org/10.5194/egusphere-egu23-1184, 2023.

Among mountain permafrost landforms, rock glaciers are composed of a heterogeneous mixture of rock debris, ice and liquid water. They can reach surface velocities of several m/yr for the most active ones, potentially causing emerging hazards linked to permafrost thawing and debris flows. As a complement to geophysical methods (georadar, active seismics, geoelectrics) providing interesting tools for investigating the subsurface, and to in-situ and remote sensing methods that track kinematics of these instabilities ⁽¹⁾, passive seismic instrumentation offers a continuous monitoring at depth.

Such instrumentation has been deployed for several years at Gugla, Tsarmine (Valais, Switzerland) and Laurichard (Hautes-Alpes, France) rock glaciers.

From seismic ambient noise, Coda Wave Interferometry has been applied to compute daily dV/V (or relative change velocity of the surface waves) ⁽²⁾⁽³⁾ which are directly linked to the elastic properties of the medium at depth, and therefore its rigidity and density ⁽⁴⁾⁽⁵⁾. For the three sites studied, seasonal variations of shear stiffness have been measured, and located by using a 1D coda wave inversion. These changes in mechanical properties of the medium are related to seasonal hydro-thermal forcing.   

We developed a simple viscoelastic model to explain the seasonal variability of the deformation rate of rock glaciers. By using observed shear stiffness as a parameter varying over time, we reconstructed well the creep rates observed, strengthening the key role of meltwater and rainfall on rock glacier dynamics at a seasonal scale. In the long term, a pluriannual seismic monitoring allows to detect changes in ice content, by tracking long-term changes in rigidity within the rock glacier body. Such permanent instrumentation paves thus the way to quantify the permafrost degradation.

References

• Kneisel, C., Hauck, C., Fortier, R., Moorman, B., (2008). Advances in geophysical methods for permafrost investigations. Permafrost and Periglacial Processes 19, 157–178. https://doi.org/10.1002/ppp.616
• Guillemot, A., Helmstetter, A., Larose, É., Baillet, L., Garambois, S., Mayoraz, R., & Delaloye, R. (2020). Seismic monitoring in the Gugla rock glacier (Switzerland): ambient noise correlation, microseismicity and modelling.Geophysical Journal International, 221(3), 1719-1735. https://doi.org/10.1093/gji/ggaa097
• Guillemot, A., Baillet, L., Garambois, S., Bodin, X., Helmstetter, A., Mayoraz, R., and Larose, E.: Modal sensitivity of rock glaciers to elastic changes from spectral seismic noise monitoring and modeling, The Cryosphere, 15, 501–529, https://doi.org/10.5194/tc-15-501-2021, 2021.
• Larose E., C. S. (2015). Environmental seismology: What ca we learn on earth surface processes with ambient noise. Journal of Applied Geophysics, 116, 62-74. https://doi.org/10.1016/j.jappgeo.2015.02.001
• Roux Ph., Guéguen Ph., Baillet L., Hamze A. (2014). Structural-change localization and monitoring through a perturbation-based inverse problem, The Journal of the Acoustical Society of America 136, 2586; https://doi.org/10.1121/1.4897403

How to cite: Guillemot, A., Larose, E., Baillet, L., Helmstetter, A., and Bodin, X.: Pluriannual seismic monitoring of rock glaciers: new insights on their dynamics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2740, https://doi.org/10.5194/egusphere-egu23-2740, 2023.

Rock glaciers are known to show changing rheological behavior related to climate forcing, resulting in varying seasonal and interannual movement velocities. We studied the relationship between movement behavior and climate forcing at the Dösen Rock Glacier, Hohe Tauern Range, using a combination of velocity data, meteorological records, ground temperature records, and a numerical modeling approach. The Dösen Rock Glacier extends from 2340 to 2620 m asl, covers an area of 0.2 km², is 950 m long and up to 300 m wide. Rather long series of annual to pluri-annual geodetic and photogrammetric movement pattern observations as well as air and ground temperature time series describing the thermal regime at the rock glacier site are available. Yet the monitoring data does not reflect movement rates on a sub-annual time scale. Hence the annual measurement campaigns performed on 17.08.2021 and 16./17.08.2022 were complemented by geodetic monitoring campaigns conducted on 06./07.07.2022 and 28.09.2022, to allow for a higher temporal resolution during summer and early fall of 2022. The observed annual movement rates between 2021 and 2022 ranged from 1.09 to 61.41 cm/a at the individual measurement points (n=34) with an overall annual mean of 33.79 cm. Analyses of the short-term monitoring indicate velocities in the range of 0.04 to 0.19 cm/d and a mean daily displacement of 0.11 cm (n=17) for the period between 06/07.07.2022 and 16/17.08.2022 whereas values ranged from 0.06 to 0.19 cm/d with a mean daily displacement of 0.14 cm (n=17) for the second period between 16/17.08.2022 and 28.09.2022. With three exceptions the horizontal movement rates at the 17 individual points, which could be measured and evaluated during both campaigns, were higher for the latter period. This reveals a general acceleration of the rock glacier during late-summer and early-autumn season.

The sub-annual geodetic dataset from 2022 is used as a starting point for bridging time scales in the supplementation of long-term monitoring efforts with numerical modeling. We present a workflow which tries to introduce climate forcing on rock glacier kinematics to the numerical mass flow simulation framework r.avaflow. For this purpose, a temperature-viscosity relation will be established. This facilitates the implementation of viscosity, variable over time, as governing input parameter for the rock glacier flow behavior. In a first step the strategy will be applied for the period from 1954 to 2022, where geodetic and photogrammetric reference data as well as digital elevation models are available, allowing for the empirical evaluation of the simulation results.

The described approach is designed to process rock glacier monitoring data (movement velocities and climate data) of different temporal resolution to be subsequently fed into an open-source modeling software with the aim to generate insights in sub-annual rock glacier movement patterns.

Acknowledgement: This work was supported by the Austrian Science Fund (FWF P18304-N10), the European Regional Development Fund (18-1-3-I) and the Hohe Tauern National Park Carinthia.

How to cite: Pfeffer, H., Kellerer-Pirklbauer, A., Kaufmann, V., and Mergili, M.: Movement pattern analysis of the Dösen Rock Glacier (Hohe Tauern Range, Austria) using a multi-method approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12685, https://doi.org/10.5194/egusphere-egu23-12685, 2023.

Mountain permafrost is increasingly retreating due to climate change. This retreat leads to positive climatic feedback loops and poses safety risks due to more frequent slope instabilities. Therefore, assessing the condition and evolution of permafrost is critical. However, mapping the extent and retreat of permafrost is not as straightforward as for other elements of the cryosphere because permafrost cannot be directly mapped by remote sensing. 
In some mountain landslides there are cones of loose debris, which are remnants of formerly ice-cemented blocks. These cones are called “molards” and they indicate the presence of an area of discontinuous permafrost at the level of the detachment zone. The initial ice-cemented blocks range in height from 50 cm to 15 meters. 

The goal of this project is to use molards as proxies of mountain permafrost degradation. Therefore, we have to understand the physical processes leading to the formation of molards as well as how these processes determine the final molard shape. 
To achieve this goal we recreate molards by using physical modeling and we have investigated molards at several Icelandic field sites. For the physical modeling it is necessary to downscale the molards to an initial cube size of ~30 cm due to current laboratory limitations. The initial blocks are created by freezing fully water saturated sediment in a wooden mold at -20°C for 48 hours. 
Sediment from actual Icelandic molards is used as well as other reduced complexity simulants with different grain sizes, grain shapes, and clay content.
We let the blocks degrade for 72 hours under a controlled and monitored laboratory environment with constant temperature and humidity conditions. We use a photogrammetric time-lapse system to create a digital elevation model of the degrading block to detect changes in hourly time-steps. 

Our initial results show that increasing clay content strongly influences the degradation speed and the final molard shape because it increases cohesion. In the field we have identified conical and trapezoidal cross-sections as the predominant shape for molards. But in the laboratory setting, high clay content means that the blocks do not degrade into this characteristic shape (without further meteorological influence). In this case,  landslide-like processes and single rockfall events dominate the molard formation process. 
For coarser grain sizes and low clay contents, rockfall is the dominant process, and both the conical and trapezoidal cross-sections can be reproduced in the experiments.

How to cite: Beck, C., Font, M., Conway, S., Philippe, M., Magnarini, G., and Morino, C.: Molards as proxies of mountain permafrost degradation: direct comparison of experimental studies and field observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4001, https://doi.org/10.5194/egusphere-egu23-4001, 2023.

Within the extensive periglacial belt of the dry Andean high mountain range (17°30’S to 35°S), the most visible expression of creeping mountain permafrost is the occurrence of rock glaciers, which have been studied systematically in the last decades (e.g. Schrott, 1996; Trombotto et al., 1999; Halla et al. 2021). Active, inactive and relict rock glaciers are included in regional and national inventories (e.g. IANIGLA-CONICET 2018), whereas the spatial distribution, internal structure and ice content within block- and talus slopes have not been explored. Thus, there is a lack of explanatory approaches and analytical data on their local and regional distribution patterns and formative controls, despite these landforms being widespread and characteristic elements in the Upper Agua Negra catchment (ca. 30°S 69°W, Province San Juan, Argentina) and covering more than 70 % of its area. We hypothesize that the permafrost bodies and the seasonally frozen active layer of these periglacial landforms store significant amounts of ice and contribute to runoff during summer months, rendering them important water reservoirs and decisive components of the water balance in the high-Andean desert landscape. Especially in light of global climate change, understanding the spatial distribution of potentially ice-rich permafrost landforms is imperative to assess available water resources, water quality and their evolution.

A holistic inventory of key cryogenic landforms with focus on block- and talus slopes will be compiled for the Agua Negra catchment. Using field and remote sensing-based geomorphological mapping (based on e.g. 12 m resolution TanDEM-X and 1 m Pléiades data), published data and statistical modeling techniques, the spatial heterogeneity of cryospheric landforms and their formation controls will be analyzed. Our regional inventory will complement the existing “Inventario Nacional de Glaciares y Ambiente Periglacial” (IANIGLA-CONICET 2018) and will further provide the basis for a first assessment of the hydrological importance of these cryogenic landforms.

Halla, C., Blöthe, J.H., Tapia Baldis, C., Trombotto Liaudat, D., Hilbich, C., Hauck, C., Schrott, L., 2021. Ice content and interannual water storage changes of an active rock glacier in the dry Andes of Argentina. The Cryosphere, 15, 1187-1213.

IANIGLA-CONICET, Ministerio de Ambiente y Desarrollo Sustentable de la Nación (2018). IANIGLA-Inventario Nacional de Glaciares y Ambiente Periglacial. Informe de la subcuenca del río Blanco. Cuenca del río San Juan, p. 62.

Trombotto, D., Buk, E.,  Hernández, J., 1999. Rock glaciers in the Southern Central Andes (appr. 33° S.L.), Mendoza, Argentina: a review. Bamberger Geographische Schriften, Selbstverlag des Faches Geographie an der Universität Bamberg, Germany, 19, 145-173.

Schrott, L., 1996. Some geomorphological-hydrological aspects of rock glaciers in the Andes (San Juan, Argentina). Zeitung für Geomorphologie, Supplementband 104, 161-173.

How to cite: Köhler, T., Ortiz, D. A., Schoch-Baumann, A., Bell, R., Stammler, M. A., Schrott, L., and Trombotto Liaudat, D.: Understanding the spatial distribution of potentially ice-rich block- and talus slopes in the Agua Negra catchment, Dry Andes, Argentina, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2290, https://doi.org/10.5194/egusphere-egu23-2290, 2023.

Sediment transport in cryospheric regions is characterized by distinct hydrogeomorphic processes and sediment sources from glacier retreat and permafrost disturbances. Ongoing atmospheric warming is melting glaciers and thawing permafrost at alarming rates. This rapid cryosphere degradation is expected to liberate unconsolidated sediment from previously frozen regions, expose glacially-conditioned sediment storage, and trigger more episodic events (e.g., floods and mass wasting). The substantial increases in readily transportable sediment and sensitive changes in hydrological conditions disturb suspended sediment concentration (SSC) and discharge (Q) relationships represented by sediment rating curves (SSC=a×Q^b with a and b as fitting parameters), creating complicated dynamics and various hysteretic patterns.

To constrain such dynamic SSC-Q relationships and reproduce the hysteresis effect, we propose a Sediment-Availability-Transport (SAT) model by extending traditional rating curves to incorporate the temperature-dependent sediment supply, pluvial processes, and sediment storage. Specifically, we highlight the sensitive response of SSC to discharge pulses triggered by rainstorms and intense melting, which can be attributed to enhanced fluvial erosion by flushing erodible hillslopes and scouring river channels.

Supported by multi-decadal daily discharge and SSC in-situ observations, the SAT-model can be parameterized, calibrated, and validated in various permafrost-dominated watersheds and glacierized watersheds. According to model validations in these pilot river basins, the SAT-model can robustly reproduce the long-term evolution, seasonal pattern, and various event-scale hysteresis in sediment transport, including clockwise, counter-clockwise, figure-eight, counter-figure-eight, and more complex hysteresis loops. Overall, the SAT-model can explain over 75% of long-term SSC variance, outperforming the traditional sediment rating curve approach by 20%.

SAT-model proposed here not only advances the understanding of sediment transport dynamics driven by climate change and cryosphere degradation, but also provides a ready-to-use model and conceptual framework to simulate and project future sediment loads in worldwide cold regions. Parts of these results have been published in Water Resources Research: Zhang et al., 2021, Constraining dynamic sediment-discharge relationships in cold environments: The sediment-availability-transport (SAT) model. (https://doi.org/10.1029/2021WR030690)

How to cite: Zhang, T., Li, D., Kettner, A., and Lu, X.: Simulating climate-cryosphere-driven sediment transport dynamics in cold regions by Sediment-Availability-Transport Model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1499, https://doi.org/10.5194/egusphere-egu23-1499, 2023.