Dalban, P.

Diotri

Faillettaz, J.

Funk, M.

Lucianaz, Claudio

Margreth, S.

Motta, E.

Vagliasindi, M.

English

PORTO Publications Open Repository TOrino

Geophysical Research Abstracts
Vol. 12, EGU2010-9973, 2010
EGU General Assembly 2010
© Author(s) 2010
Monitoring of Grandes Jorasses hanging glacier (Aosta Valley, Italy):
improving monitoring techniques for glaciers instability
marco vagliasindi (1), Martin Funk (2), Jerome Faillettaz (2), Pierre Dalban (2), Claudio Lucianaz (1), Fabrizio
Diotri (1), Elena Motta (1), and Stephan Margreth (3)
(1) Fondazione Montagna sicura - Courmayeur - Aosta Valley - Italy, (2) Laboratory of Hydraulics, Hydrology and Glaciology
– Swiss Federal Institute of technology – Zurich – CH, (3) Institute for Snow and Avalanche Research SLF DAVOS, CH
Grandes Jorasses serac is an unbalanced hanging glacier located on the south side of Mont Blanc Massif (Aosta
Valley – Italy). It stands above Ferret Valley, a famous and most frequented touristic site both in winter and
summer. Historical data and morphological evidences show that the glacier is subject to recurrent icefalls which
can be dangerous especially in winter, as they can trigger catastrophic combined snow and ice avalanches.
Serac dynamic was monitored in 1997-98 by prof. M Funk (ETH Zurich) by means of temperature and topographic
measurement. These allowed to forecast the breakdown within a 2 days time.
Thanks to a monitoring program, a new instability could be recognized in autumn 2008: a crevasse opening in the
lower part of the hanging glacier. A new monitoring system was installed recently, consisting of stakes with prisms
on serac surface and an automatic total station (theodolite plus distantiometer) sited on the valley floor. Monitoring
is based on an empirically based power law (developed by ETH) that describes the increasing displacement
rate before collapse. This monitoring system requires to measure displacement rate of the serac continuously.
Although the topographic system is so far the state-of-the.art method, it implies some troubles: (i) the difficulty
in placing stakes on the steep and dangerous glacier surface; (ii) potential instability of stakes themselves due to
snow pressure in winter and surface ice melting in summer; (iii) impossibility to carry out measurement in case of
cloudy or stormy weather, which is rather a frequent situation on Grandes Jorasses peak. Moreover, hazard and
risk management require some more informations, such as the instable ice mass volume.
New technologies have been applied, and are still under test, to achieve a more reliable monitoring system and a
better understanding of the serac dynamics. Close-range photogrammetry techniques have been used, allowing to
process helicopter-taken images and obtain quantitative data about the serac volume and crevasses widening.
A low-cost GPS station has been installed in the upper part of the serac, in order to obtain long-term, continuous
displacement data even in bad weather conditions. A seismograph has been installed to measure the seismic
activity of the serac. The latter, as observed by ETH, significantly evolves before the seracfall; thus, the record of
the seismic activity can be used to forecast the break-off.
Finally, a ground-based SAR system has been tested to infer seracs displacement.
Possible avalanches scenarios consequent to an icefall have been calculated by numerical simulation by the SLF
Institute of Davos.
In-situ measurement techniques have to be designed to resist often in the difficult environmental conditions (low
temperature, frost, wind), dealing, e.g. with power supply and data transmission, and purpose-made technical
solutions are often necessary. The development of these techniques will contribute to an improved understanding
of the seracs dynamics and provide a more reliable monitoring tool.


Monitoring of Grandes Jorasses hanging glacier (Aosta Valley, Italy):improving monitoring techniques for glaciers instability

M. VAGLIASINDI

M. FUNK

J. FAILLETTAZ

P. DALBAN

F, DIOTRI

E. MOTTA AND S. MARGRETH

LUCIANAZ, CLAUDIO

PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)

05 August 2020POLITECNICO DI TORINORepository ISTITUZIONALEMonitoring of Grandes Jorasses hanging glacier (Aosta Valley, Italy):improving monitoring techniques for glaciersinstability / M. VAGLIASINDI; M. FUNK; J. FAILLETTAZ; P. DALBAN; LUCIANAZ C.; F; DIOTRI; E. MOTTA AND S.MARGRETH. - 12(2010). ((Intervento presentato al convegno European Geosciences Union - EGU tenutosi a Vienna nel02-07 May 2010.OriginalMonitoring of Grandes Jorasses hanging glacier (Aosta Valley, Italy):improving monitoring techniques forglaciers instabilityPublisher:PublishedDOI:Terms of use:openAccessPublisher copyright(Article begins on next page)This article is made available under terms and conditions as specified in the  corresponding bibliographic description inthe repositoryAvailability:This version is available at: 11583/2370136 since:Geophysical Research AbstractsVol. 12, EGU2010-9973, 2010EGU General Assembly 2010© Author(s) 2010Monitoring of Grandes Jorasses hanging glacier (Aosta Valley, Italy):improving monitoring techniques for glaciers instabilitymarco vagliasindi (1), Martin Funk (2), Jerome Faillettaz (2), Pierre Dalban (2), Claudio Lucianaz (1), FabrizioDiotri (1), Elena Motta (1), and Stephan Margreth (3)(1) Fondazione Montagna sicura - Courmayeur - Aosta Valley - Italy, (2) Laboratory of Hydraulics, Hydrology and Glaciology– Swiss Federal Institute of technology – Zurich – CH, (3) Institute for Snow and Avalanche Research SLF DAVOS, CHGrandes Jorasses serac is an unbalanced hanging glacier located on the south side of Mont Blanc Massif (AostaValley – Italy). It stands above Ferret Valley, a famous and most frequented touristic site both in winter andsummer. Historical data and morphological evidences show that the glacier is subject to recurrent icefalls whichcan be dangerous especially in winter, as they can trigger catastrophic combined snow and ice avalanches.Serac dynamic was monitored in 1997-98 by prof. M Funk (ETH Zurich) by means of temperature and topographicmeasurement. These allowed to forecast the breakdown within a 2 days time.Thanks to a monitoring program, a new instability could be recognized in autumn 2008: a crevasse opening in thelower part of the hanging glacier. A new monitoring system was installed recently, consisting of stakes with prismson serac surface and an automatic total station (theodolite plus distantiometer) sited on the valley floor. Monitoringis based on an empirically based power law (developed by ETH) that describes the increasing displacementrate before collapse. This monitoring system requires to measure displacement rate of the serac continuously.Although the topographic system is so far the state-of-the.art method, it implies some troubles: (i) the difficultyin placing stakes on the steep and dangerous glacier surface; (ii) potential instability of stakes themselves due tosnow pressure in winter and surface ice melting in summer; (iii) impossibility to carry out measurement in case ofcloudy or stormy weather, which is rather a frequent situation on Grandes Jorasses peak. Moreover, hazard andrisk management require some more informations, such as the instable ice mass volume.New technologies have been applied, and are still under test, to achieve a more reliable monitoring system and abetter understanding of the serac dynamics. Close-range photogrammetry techniques have been used, allowing toprocess helicopter-taken images and obtain quantitative data about the serac volume and crevasses widening.A low-cost GPS station has been installed in the upper part of the serac, in order to obtain long-term, continuousdisplacement data even in bad weather conditions. A seismograph has been installed to measure the seismicactivity of the serac. The latter, as observed by ETH, significantly evolves before the seracfall; thus, the record ofthe seismic activity can be used to forecast the break-off.Finally, a ground-based SAR system has been tested to infer seracs displacement.Possible avalanches scenarios consequent to an icefall have been calculated by numerical simulation by the SLFInstitute of Davos.In-situ measurement techniques have to be designed to resist often in the difficult environmental conditions (lowtemperature, frost, wind), dealing, e.g. with power supply and data transmission, and purpose-made technicalsolutions are often necessary. The development of these techniques will contribute to an improved understandingof the seracs dynamics and provide a more reliable monitoring tool.

https://iris.polito.it/retrieve/handle/11583/2370136/52893/EGU2010-9973.pdf

Monitoring of Grandes Jorasses hanging glacier (Aosta Valley, Italy):improving monitoring techniques for glaciers instability

Abstract

Similar works

Full text

Available Versions

PORTO Publications Open Repository TOrino

PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)