Recent structural evolution of Forni Glacier tongue (Ortles-Cevedale Group, Central Italian Alps)
TL;DR: In this article, the authors document the occurrence and evolution of brittle and ductile structures on the tongue of Forni Glacier, Ortles-Cevedale Group, Central Italian Alps, between 2003 and 2014.
Abstract: Structural glaciology yields important details about the evolution of glacier dynamics in response to climate change. The maps provided here document the occurrence and evolution of brittle and ductile structures on the tongue of Forni Glacier, Ortles-Cevedale Group, Central Italian Alps, between 2003 and 2014. Through the remote sensing-based analysis of structures, we found evidence of brittle fractures such as crevasses, faults and ring faults, and ductile structures such as ogives at the base of the icefall in the eastern glacier tongue. Although each of the three glacier tongues have evolved differently, a reduction in flow-related dynamics and an increase in the number of collapse structures occurred over the study period. Analysis of the glacier structural evolution based on the numbers and the locations of different structures, suggest a slowdown of glacier flow on the eastern tongue. The recent evolution of the glacier also suggests that the occurrence of a disintegration scenario is like...
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TL;DR: In this paper, the authors analyzed the potential of different survey technologies to analyze hazards of the Forni Glacier, an important geosite located in Stelvio Park (Italy) and compared point clouds generated from an unmanned aerial vehicle (UAV) survey, close-range photogrammetry and terrestrial laser scanning (TLS).
Abstract: . Tourists and hikers visiting glaciers all year round face hazards such as
sudden terminus collapses, typical of such a dynamically evolving
environment. In this study, we analyzed the potential of different survey
techniques to analyze hazards of the Forni Glacier, an important geosite
located in Stelvio Park (Italian Alps). We carried out surveys in the
2016 ablation season and compared point clouds generated from an unmanned aerial
vehicle (UAV) survey, close-range photogrammetry and terrestrial laser
scanning (TLS). To investigate the evolution of glacier hazards and evaluate
the glacier thinning rate, we also used UAV data collected in 2014 and a
digital elevation model (DEM) created from an aerial photogrammetric survey
of 2007. We found that the integration between terrestrial and UAV
photogrammetry is ideal for mapping hazards related to the glacier collapse,
while TLS is affected by occlusions and is logistically complex in glacial
terrain. Photogrammetric techniques can therefore replace TLS for glacier
studies and UAV-based DEMs hold potential for becoming a standard tool in
the investigation of glacier thickness changes. Based on our data sets, an
increase in the size of collapses was found over the study period, and the
glacier thinning rates went from 4.55 ± 0.24 m a −1 between 2007
and 2014 to 5.20 ± 1.11 m a −1 between 2014 and 2016.
79 citations
Cites background from "Recent structural evolution of Forn..."
..., 2010) or the collapse of ice cavities (Gagliardini et al., 2011; Azzoni et al., 2017)....
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...While often overlooked, these collapse structures are particularly hazardous for mountaineers and they are likely to increase under a climate change scenario (Azzoni et al., 2017)....
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...…causes changes in water resources, with an initial increase in discharge due to enhanced melt followed by a long-term reduction, affecting drinking water supply, irrigation and hydropower production (Kaab et al., 2005b), along with a rising occurrence of structural collapses (Azzoni et al., 2017)....
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...Less severe hazards, but still particularly threatening for mountaineers, are the detachment of seracs (Riccardi et al., 2010) or the collapse of ice cavities (Gagliardini et al., 2011; Azzoni et al., 2017)....
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...It has also undergone profound changes in dynamics in recent years, such as the loss of ice flow from the eastern accumulation basin towards its tongue and the evidence of collapsing areas on the eastern tongue (see Fig. 2d; Azzoni et al., 2017)....
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TL;DR: In this article, the authors used a scoping review method to explore integrated impacts of climate change on glaciers from the academic literature, which included a wide range of both research and non-research-based data or information.
57 citations
16 Jan 2018
TL;DR: In this article, the authors reported that the expansion of supraglacial debris on worldwide mountain glaciers has been reported over the last decades, and works dealing with the detection and mapping of suplaglastic debris and d...
Abstract: Over the last decades, the expansion of supraglacial debris on worldwide mountain glaciers has been reported. Nevertheless, works dealing with the detection and mapping of supraglacial debris and d...
27 citations
01 Jan 2020
TL;DR: In this article, the authors analyzed the recent involution of glaciers in the Bernina group (Italy), which are shrinking thus permitting a rapid enlargement of the forelands of the country.
Abstract: We analysed the recent involution of glaciers in the Bernina group (Italy), which are shrinking thus permitting a rapid enlargement of the forelands. We delimited glacier outlines upon aerial photo...
24 citations
Cites background or result from "Recent structural evolution of Forn..."
...Other changes linked to glacier shrinkage are collapse structures at the glacier surface and a modified crevasse evolution which strongly influence glacier hazard and risk conditions (Diolaiuti et al., 2006) thus requiring accurate and updated surveys (Azzoni et al., 2017; Fugazza et al., 2018)....
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...These results are consistent with those reported by Paul et al. (2004, 2007), Maragno et al. (2009), Pelto (2010) and Diolaiuti et al. (2011), Azzoni et al. (2017, 2018)....
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TL;DR: In this paper, a characterization of Cryoconite from two Alpine glaciers is presented, and it is shown that it is significantly more radioactive than the matrices usually adopted for the environmental monitoring of radioactivity, such as lichens and mosses, with activity concentrations exceeding 10'000'Bq kg −1 for single radionuclides.
Abstract: . Cryoconite is rich in natural and artificial
radioactivity, but a discussion about its ability to accumulate
radionuclides is lacking. A characterization of cryoconite from two Alpine
glaciers is presented here. Results confirm that cryoconite is significantly
more radioactive than the matrices usually adopted for the environmental
monitoring of radioactivity, such as lichens and mosses, with activity
concentrations exceeding 10 000 Bq kg −1 for single radionuclides. This
makes cryoconite an ideal matrix to investigate the deposition and
occurrence of radioactive species in glacial environments. In addition,
cryoconite can be used to track environmental radioactivity sources. We have
exploited atomic and activity ratios of artificial radionuclides to identify
the sources of the anthropogenic radioactivity accumulated in our samples.
The signature of cryoconite from different Alpine glaciers is compatible
with the stratospheric global fallout and Chernobyl accident products.
Differences are found when considering other geographic contexts. A
comparison with data from literature shows that Alpine cryoconite is
strongly influenced by the Chernobyl fallout, while cryoconite from other
regions is more impacted by events such as nuclear test explosions and
satellite reentries. To explain the accumulation of radionuclides in
cryoconite, the glacial environment as a whole must be considered, and
particularly the interaction between ice, meltwater, cryoconite and
atmospheric deposition. We hypothesize that the impurities originally
preserved into ice and mobilized with meltwater during summer, including
radionuclides, are accumulated in cryoconite because of their affinity for
organic matter, which is abundant in cryoconite. In relation to these
processes, we have explored the possibility of exploiting radioactivity to date
cryoconite.
23 citations
Cites background from "Recent structural evolution of Forn..."
...To the best of our knowledge, the first evidence of the accumulation of radionuclides in cryoconite was reported by Tomadin et al. (1996), who found high levels of anthropogenic radioactivity in cryoconite samples from the European Alps....
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...By comparing the 240Pu/239Pu ratio of global fallout and of modern snow deposited in the Alps (Gückel et al., 2017), it is possible to further discuss the Pu sources in cryoconite....
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...The Morteratsch and Forni glaciers are located in the European Alps and are situated ∼ 50 km apart (Fig....
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...Our study is focused on cryoconite samples from the European Alps, but results from other regions of the global cryosphere confirm our findings, proving that the accumulation of radioactivity is not a local phenomenon but involves worldwide glaciated areas....
[...]
...Owing to retreat of the glacier, the connections between the basins have become weaker and the glacier is now fragmented in two parts (Azzoni et al., 2017)....
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References
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01 Jan 1969
TL;DR: In this paper, the transformation of snow to ice mass balance heat budget and climatology structure and deformation of ice hydraulics and glaciers glacier sliding deformation, subglacial till structures and fabrics in glaciers and ice sheets distribution of temperature in glaciers, flow of ice shelves and ice streams non-steady flow of glaciers, ice sheets surging and tidewater glaciers ice core studies.
Abstract: The transformation of snow to ice mass balance heat budget and climatology structure and deformation of ice hydraulics and glaciers glacier sliding deformation of subglacial till structures and fabrics in glaciers and ice sheets distribution of temperature in glaciers and ice sheets steady flow of glaciers and ice sheets flow of ice shelves and ice streams non-steady flow of glaciers and ice sheets surging and tidewater glaciers ice core studies.
4,450 citations
"Recent structural evolution of Forn..." refers background in this paper
...They are generally confined to the shallower glacier layers and reflect patterns of extensional stress (Cuffey & Paterson, 2010)....
[...]
Geological Survey of Denmark and Greenland1, Victoria University of Wellington2, University of Zurich3, International Centre for Integrated Mountain Development4, University of Pisa5, University of Magallanes6, Polytechnic University of Valencia7, Natural Resources Canada8, Nagoya University9, University of Silesia in Katowice10, University of Oslo11, Stockholm University12, Nichols College13, Moscow State University14, University of Innsbruck15, Geological Survey of India16, Met Office17, Higher University of San Andrés18
TL;DR: This article provided an overview and analysis of the main observational datasets compiled by the World Glacier Monitoring Service (WGMS) and showed that the rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed and probably also for recorded history.
Abstract: Observations show that glaciers around the world are in retreat and losing mass. Internationally coordinated for over a century, glacier monitoring activities provide an unprecedented dataset of glacier observations from ground, air and space. Glacier studies generally select specific parts of these datasets to obtain optimal assessments of the mass-balance data relating to the impact that glaciers exercise on global sea-level fluctuations or on regional runoff. In this study we provide an overview and analysis of the main observational datasets compiled by the World Glacier Monitoring Service (WGMS). The dataset on glacier front variations (�42000 since 1600) delivers clear evidence that centennial glacier retreat is a global phenomenon. Intermittent readvance periods at regional and decadal scale are normally restricted to a subsample of glaciers and have not come close to achieving the maximum positions of the Little Ice Age (or Holocene). Glaciological and geodetic observations (�5200since 1850) show that the rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed and probably also for recorded history, as indicated also in reconstructions from written and illustrated documents. This strong imbalance implies that glaciers in many regions will very likely suffer further ice loss, even if climate remains stable.
548 citations
"Recent structural evolution of Forn..." refers background in this paper
...Considering the glaciological balance, the global mean annual value of early twenty-first-century observations (2001–2010) is the most negative since the mid-nineteenth century, with −0.54 m w.e. a–1 and glaciers presently contribute to 1.37 mm a−1 of mean sea-level rise (Zemp et al., 2015)....
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TL;DR: In this paper, the authors provide a detailed structural analysis of the Larsen B ice shelf prior to its collapse in February-March 2002, showing that large open-rift systems were present offshore of Foyn Point and Cape Disappointment.
Abstract: This study provides a detailed structural glaciological analysis of changes in surface structures on the Larsen B ice shelf on the Antarctic Peninsula prior to its collapse in February-March 2002. Mapped features include the ice-shelf front, rifts, crevasses, longitudinal linear surface structures and meltwater features. We define domains on the ice shelf related to glacier source areas and demonstrate that, prior to collapse, the central Larsen B ice shelf consisted of four sutured flow units fed by Crane, Jorum, Punchbowl and Hektoria/Green/Evans glaciers. Between these flow units were 'suture zones' of thinner ice where the feeder glaciers merged. Prior to collapse, large open-rift systems were present offshore of Foyn Point and Cape Disappointment. These rifts became more pronounced in the years preceding break-up, and ice blocks in the rifts rotated because of the strong lateral shear in this zone. Velocity mapping of the suture zones indicates that the major rifts were not present more than about 20 years ago. We suggest that the ice shelf was preconditioned to collapse by partial rupturing of the sutures between flow units. This, we believe, was the result of ice-shelf front retreat during 1998- 2000, reducing the lateral resistive stress on the upstream parts of the shelf and glacier flow units, ice-shelf thinning and pre-shelf-break-up glacier acceleration.
182 citations
TL;DR: Hambrey, Michael, Murray, T., Glasser, N.F., Hubbard, A., (2005) 'Structure and changing dynamics of a polythermal valley glacier on a centennial timescale: Midre Lovenbreen, Svalbard', Journal of Geophysical Research 110 pp. as mentioned in this paper
Abstract: Hambrey, Michael, Murray, T., Glasser, N.F., Hubbard, A., (2005) 'Structure and changing dynamics of a polythermal valley glacier on a centennial timescale: Midre Lovenbreen, Svalbard', Journal of Geophysical Research 110 pp. 1-19 RAE2008
93 citations
"Recent structural evolution of Forn..." refers background in this paper
...…Glasser, Nienow, & Mair, 2005; Hambrey & Lawson, 2000; Jennings, Hambrey, Glasser, James, & Hubbard, 2016), but a few have assessed the temporal evolution of glacier structures in response to evolving stress and strain regimes (Glasser & Scambos, 2008; Hambrey et al., 2005; Phillips et al., 2017)....
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TL;DR: In this paper, the authors made several tens of boundary-element models of various geometries and subject to different loading conditions, and found that overpressure or underpressure in the chamber as the only loading is unlikely to initiate ring faults.
Abstract: Ring faults in volcanoes have been recognized for a long time, but their mechanics of formation is still poorly understood. While the subsidence on a ring fault during a large eruption from the associated chamber is easily understood, the initiation of the fault itself has been difficult to explain. For a ring fault to form, the tensile and shear stresses at the surface of the volcano must peak at a certain radial distance from the surface point above the center of the chamber. Empirical evidence, however, shows that during most periods of unrest in active volcanoes the stress field is not favorable for the initiation of ring faults. We made several tens of boundary-element models of magma chambers of various geometries and subject to different loading conditions. The results indicate that overpressure or underpressure in the chamber as the only loading is unlikely to initiate ring faults. For a spherical chamber subject to horizontal extension or doming, and a sill-like chamber subject to horizontal extension, the tensile and shear stresses at the surface of the volcano peak at a certain radial distance from the surface point above the center of the chamber. Then, however, the maximum stresses occur at the boundary of the chamber itself, which would normally lead to sheet injection rather than to ring-fault formation. By contrast, a sill-like magma chamber subject to doming gives rise to a stress field suitable for the initiation of a ring fault.
88 citations