Physical and biological features of an active rock glacier in the Italian Alps

The Holocene ◽  
2014 ◽  
Vol 24 (11) ◽  
pp. 1624-1631 ◽  
Author(s):  
Mauro Gobbi ◽  
Francesco Ballarin ◽  
Chiara Compostella ◽  
Valeria Lencioni ◽  
Roberto Seppi ◽  
...  
Keyword(s):  
Grain Size ◽  
Plant Distribution ◽  
Coarse Grained ◽  
Italian Alps ◽  
Rock Glacier ◽  
Biological Features ◽  
Rock Glaciers ◽  
Specific Species ◽  
Physical Features ◽  
Unique Species

We report on the key physical features of an active rock glacier that influence the distribution of plants and arthropods. We also perform a comparison with neighboring scree slope and alpine grassland to test whether the environmental features of the rock glacier drive the presence of specific species assemblages. Compared with scree slope and grassland, the studied rock glacier provides particular physical features that determine the presence of unique species. Plant distribution is mainly driven by grain size. Arthropod distribution is linked to grain size, with cold-adapted species found on areas with coarse-grained deep debris, which also shows a distinctive temperature regime with very low values throughout the year. On the basis of these findings, we advance the hypothesis that rock glaciers provide specific ecological conditions creating potential refugia for cold-demanding species during warm climatic periods.

scholarly journals Rainfall as primary driver of discharge and solute export from rock glaciers: The Col d'Olen Rock Glacier in the NW Italian Alps

2018 ◽  
Vol 639 ◽  
pp. 316-330 ◽  
Author(s):  
Nicola Colombo ◽  
Stephan Gruber ◽  
Maria Martin ◽  
Mery Malandrino ◽  
Andrea Magnani ◽  
...  
Keyword(s):  
Italian Alps ◽  
Rock Glacier ◽  
Primary Driver ◽  
Rock Glaciers

Alpine stream characterization through the lens of hydrochemistry: a comparison study from two high-elevation catchments (Eastern Italian Alps) 

2021 ◽  
Author(s):  
Michael Engel ◽  
Stefano Brighenti ◽  
Werner Tirler ◽  
Rudi Nadalet ◽  
Volkmar Mair ◽  
...  
Keyword(s):  
Stream Water ◽  
High Elevation ◽  
River Network ◽  
Main Stream ◽  
Italian Alps ◽  
Rock Glacier ◽  
Ice Melt ◽  
Rock Glaciers ◽  
Alpine Stream ◽  
Thawing Permafrost

<p>High-elevation catchments are rapidly changing as glaciers retreat and permafrost thawing intensifies. Consequently, alpine stream hydrochemistry is shifting but the interaction with complex hydrological and geological settings often confounds the effect of the climatic signal. To evaluate the effect of different glacier coverage and rock glacier presence, our study involves a multi-parameter approach of different tracers in two high-elevation catchments. Both catchments (Schnals and Martell; Eastern Italian Alps) share a comparable metamorphic geology but contrast in their glacier cover (4% and 22%, respectively) and abundance of active rock glaciers (numerous in the Schnals catchment).</p><p>Based on these different settings, we hypothesized that i) the glacier melt contribution at the daily and monthly scale in Martell is larger than in Schnals, ii) metamorphic catchments share similar hydrochemical patterns along the river network, and iii) rock glacier meltwaters affect more strongly the hydrochemistry of the main stream in Schnals than in Martell, given the higher abundance of active rock glaciers in the former catchment.</p><p>From June 2019 to October 2020, we carried out a monthly sampling of stream water along the main river, major tributaries, springs and a rock glacier. Snowmelt and ice melt (only at Martell) were occasionally sampled as well. Rain was collected on a monthly basis. Electrical conductivity of water samples was measured on-site while stable water isotopes and concentrations of major, minor, and trace elements were measured in the laboratory.</p><p>Our results indicate that the isotopic composition of streams and tributaries in Martell mainly originated from snowmelt and ice melt, with a minor contribution from groundwater. In contrast, the contribution of precipitation, shallow groundwater, and rock glaciers was larger in the Schnals catchment. The two catchments showed distinct hydrochemical patterns, based on their different elemental concentrations. Mostly during the glacier ablation period and autumn, alkali elements dominated Schnals hydrochemistry, whereas arsenic and strontium characterized the stream hydrochemistry of Martell. Concentrations of metals and metalloids had a sharp increase during autumn, when thawing permafrost and the subglacial drainage was highest, thus affecting the hydrochemistry of the entire river network. As thawing permafrost increasingly influences the quality of freshwaters in deglaciating catchments, efforts must be dedicated to the long-term monitoring of alpine river networks, given the potential implications for human health and ecosystem quality.</p>

A complementary kinematic approach to inventory rock glaciers applied to case studies of the Swiss and Italian Alps

2021 ◽  
Author(s):  
Aldo Bertone ◽  
Chloé Barboux ◽  
Francesco Brardinoni ◽  
Reynald Delaloye ◽  
Volkmar Mair ◽  
...  
Keyword(s):  
Swiss Alps ◽  
Research Network ◽  
Italian Alps ◽  
The South ◽  
Rock Glacier ◽  
Climatic Forcing ◽  
Mountain Permafrost ◽  
Rock Glaciers ◽  
Kinematic Information ◽  
Velocity Class

<p>Rock glaciers are the best visual expression of creeping mountain permafrost. Their dynamics, which largely depend on climatic forcing, provide information about the mountain permafrost and may locally pose risk to infrastructures.</p><p>The International Permafrost Association (IPA) Action Group on Rock glacier inventories and kinematics, launched in 2018, fosters the activities of a research network focused on the definition of standardized guidelines for inventorying rock glaciers, including information on rock-glacier displacement rate. The ESA Permafrost_CCI project further sustains this initiative, and proposes a standardized method to implement kinematics-based rock glacier inventories.</p><p>The proposed method exploits interferometric data from spaceborne Synthetic Aperture Radar (InSAR) to derive the kinematic information of existing or newly-compiled rock glacier inventories. In particular, areas identified as slope movements within rock glacier polygons are delineated on interferograms as “moving areas”, and are assigned a velocity class. Subsequently, a specific kinematic class is assigned to each rock glacier unit according to the velocity class and extension of the relevant moving areas.</p><p>This method is applied on two regions: the Western part of the Swiss Alps and the South-Western part of the South Tyrol (Italian Alps). Both are located at the same latitude, with rock glaciers in the Swiss part lying at slightly higher altitudes, and experiencing higher mean annual precipitation. Rock glacier polygons were drawn from existing inventories, the kinematic information was extracted exploiting InSAR data acquired between 2018 and 2019 from the Sentinel-1 constellation.</p><p>In the Swiss and Italian parts, we inventoried 660 and 783 moving areas (1443 in total). Collectively, it was possible to assign a kinematic attribute to 913 rock glaciers, providing a more objective and quantitative activity classification (compared to the qualitative active, inactive, and relict categories). In the Swiss part, 14% of the rock glaciers are moving in the magnitude order of a meter/year or faster, 43% in the magnitude order of one to several dm/yr, 36% from one to several cm/yr, the others are with unreliable movements (7%). In the Italian part, these percentages are 1% (meter/year or faster), 42% (one to several dm/yr), 39% (one to several cm/yr) and 18% (no reliable), respectively. Preliminary analyses on the Italian part are conducted on 467 additional rock glaciers recognized as geomorphologically relict: 68% are not moving or not moving fast enough to be detected, 9% have sectors moving up to several cm/yr, and the remaining 23% of relict rock glaciers have no reliable information on movement.</p><p>Preliminary results show how this approach allows to provide complementary kinematic information to the geomorphological approach, improving the knowledge on the activity status in a given time and in a given region. Since several studies have reported trends towards displacement acceleration, applying this approach over long periods will allow assessing the response of a wide selection of landforms to (warmer) climatic forcing. Furthermore, this approach is a very useful tool to help select representative rock glaciers of a region, on which to apply more accurate monitoring approaches.</p>

Rock glacier sediment, kinematics and geomorphometry: a study case from the Eastern Italian Alps

2021 ◽  
Author(s):  
Federica Minotti ◽  
Christian Kofler ◽  
Bernhard Gems ◽  
Volkmar Mair ◽  
Francesco Comiti
Keyword(s):  
High Mountain ◽  
Ice Melting ◽  
Italian Alps ◽  
Rock Glacier ◽  
Tauern Window ◽  
Transport Distance ◽  
Glacier System ◽  
Mountain Environments ◽  
Rock Glaciers ◽  
Unconsolidated Rock

<p>Rock glaciers are important geomorphological structures of high mountain environments and fundamental indicators for permafrost. They consist of unconsolidated rock debris – generally derived from talus or till - held together by ice, moving slowly downslope due to the gravitation in combination with uncountable freeze-thaw-cycles in the active layer. The downslope movement of rock glaciers leads to lobate structures with depressed areas as well as ridges where the sediments tend to accumulate, creating a typical surface morphology defined as "ridges and furrows". This study focuses on the analysis of one rock glacier system located in the Pfitsch/Vizze valley (South Tyrol), in the Eastern Italian Alps.  The debris in this area comprises exclusively the granitic Central Gneiss of the Tauern window. Rock glacier sediment derives from talus, consisting essentially of more or less foliated to planar angular material, which was essentially formed by frost weathering. The size and shape of sediments present at the surface of the rock glacier system were analyzed in correlation with displacement and geomorphometry, with the hypothesis that sediments shape and size at different sites across the rock glacier might relate to its past and present dynamics. The displacement analyses were carried out to quantify rock glaciers movements during the last 20 years, and the geomorphometrical characteristics were investigated to identify specific geometrical attributes that may be linked to internal ice changes.<br>Clasts analysis showed how rock glacier sediments are very heterogeneous, with dimensions being mainly determined by transport distance, and sphericity and roundness by lithology. A role of sediments characteristics on displacement rate did not turn out evident. Convexities and concavities observed on the study site are apparently created respectively by the accumulation of sediments and the collapse of the structure due to the internal ice melting. Indeed, the recent, marked increase in air temperature observed in the last decades in the Alps has likely caused an accelerated ice melting in the less protected – in terms of solar radiation – rock glaciers, as is the case for our study area. Sediments here are no longer bound by ice and have become rather unstable. Therefore, the monitoring of rock glaciers is fundamental to anticipate future changes in the type and magnitude of natural hazards originating at high elevations, as thicker layers of sediments are becoming increasingly unstable.</p>

Changes of rock glacier vegetation in 25 years of climate warming in the Italian Alps

CATENA ◽  
2021 ◽  
Vol 206 ◽  
pp. 105562
Author(s):  
Nicoletta Cannone ◽  
Silvia Piccinelli
Keyword(s):  
Climate Warming ◽  
Italian Alps ◽  
Rock Glacier

scholarly journals Submarine lava deltas of the 2018 eruption of Kīlauea volcano

2021 ◽  
Vol 83 (4) ◽  
Author(s):  
S. Adam Soule ◽  
Michael Zoeller ◽  
Carolyn Parcheta
Keyword(s):  
Grain Size ◽  
Pore Pressure ◽  
Mechanistic Model ◽  
Large Fraction ◽  
Volcanic Hazards ◽  
Lava Flows ◽  
Coarse Grained ◽  
Fine Grained ◽  
Fine Grain ◽  
Delta Formation

AbstractHawaiian and other ocean island lava flows that reach the coastline can deposit significant volumes of lava in submarine deltas. The catastrophic collapse of these deltas represents one of the most significant, but least predictable, volcanic hazards at ocean islands. The volume of lava deposited below sea level in delta-forming eruptions and the mechanisms of delta construction and destruction are rarely documented. Here, we report on bathymetric surveys and ROV observations following the Kīlauea 2018 eruption that, along with a comparison to the deltas formed at Pu‘u ‘Ō‘ō over the past decade, provide new insight into delta formation. Bathymetric differencing reveals that the 2018 deltas contain more than half of the total volume of lava erupted. In addition, we find that the 2018 deltas are comprised largely of coarse-grained volcanic breccias and intact lava flows, which contrast with those at Pu‘u ‘Ō‘ō that contain a large fraction of fine-grained hyaloclastite. We attribute this difference to less efficient fragmentation of the 2018 ‘a‘ā flows leading to fragmentation by collapse rather than hydrovolcanic explosion. We suggest a mechanistic model where the characteristic grain size influences the form and stability of the delta with fine grain size deltas (Pu‘u ‘Ō‘ō) experiencing larger landslides with greater run-out supported by increased pore pressure and with coarse grain size deltas (Kīlauea 2018) experiencing smaller landslides that quickly stop as the pore pressure rapidly dissipates. This difference, if validated for other lava deltas, would provide a means to assess potential delta stability in future eruptions.

scholarly journals Observations on a Debris-Covered Polar Glacier “Whisky Glacier”, James Ross Island, Antarctic Peninsula, Antarctica

1987 ◽  
Vol 33 (115) ◽  
pp. 300-310 ◽  
Author(s):  
T.J.H. Chinn ◽  
A. Dillon
Keyword(s):  
Antarctic Peninsula ◽  
Rock Glacier ◽  
Freezing Front ◽  
Extensive Area ◽  
Free Zone ◽  
Rock Glaciers ◽  
James Ross Island ◽  
Polythermal Glacier ◽  
Powerful Mechanism

Abstract“Whisky Glacier” on James Ross Island, Antarctic Peninsula, comprises anévéand clean ice trunk surrounded by an extensive area of debris-covered ice resembling a rock glacier. The debris-free trunk of the glacier abuts abruptly against the broad, totally debris-covered tongue at a number of concentric zones where debris-laden beds crop out at the surface in a manner similar to the “inner moraine” formations of many polar glaciers.Ice structures and foliation suggest that “Whisky Glacier” is a polythermal glacier which is wet-based under the debris-free zone, and dry-based under the debris-covered zone. It is surmised that the glacier sole crosses the freezing front close to where the basal debris beds are upwarped towards the surface. Here, basal water is confined, and freezes to the under side of the glacier in thick beds of regelation ice which are uplifted to the surface along with the debris-laden beds. Ablation losses effectively cease beneath the blanket of debris covering the tongue.The transition from wet-based to dry-based conditions at the glacier sole is a powerful mechanism for entraining debris into a glacier and, in the case of “Whisky Glacier”, for lifting debris to the surface. It is suggested that this may be a mechanism for forming some polar rock glaciers.

The Effect of Grain Size on Superplastic Deformation of Ti-6Al-4V Alloy

2007 ◽  
Vol 551-552 ◽  
pp. 387-392 ◽  
Author(s):  
Wen Juan Zhao ◽  
Hua Ding ◽  
D. Song ◽  
F.R. Cao ◽  
Hong Liang Hou
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Superplastic Deformation ◽  
Initial Strain Rate ◽  
Deformation Mode ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Transmission Electron ◽  
Grain Growth Model

In this study, superplastic tensile tests were carried out for Ti-6Al-4V alloy using different initial grain sizes (2.6 μm, 6.5μm and 16.2 μm) at a temperature of 920°C with an initial strain rate of 1×10-3 s-1. To get an insight into the effect of grain size on the superplastic deformation mechanisms, the microstructures of deformed alloy were investigated by using an optical microscope and transmission electron microscope (TEM). The results indicate that there is dramatic difference in the superplastic deformation mode of fine and coarse grained Ti-6Al-4V alloy. Meanwhile, grain growth induced by superplastic deformation has also been clearly observed during deformation process, and the grain growth model including the static and strain induced part during superplastic deformation was utilized to analyze the data of Ti-6Al-4V alloy.

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