WP1 - Geophysical investigation of the Argentière Glacier (Chamonix Valley, French Alps)

– Scientific coordinator : Florent Gimbert (IGE, UGA)

Introduction

Glacier dynamics regulates the advection of ice towards lower elevations with higher temperature and melt rates, and thus controls the supply of fresh water to populations for mountain glaciers (Huss et al., 2014) and to oceans for ice sheets (Ritz et al., 2015). Compared to viscous flow, glacier fracturing, basal sliding and subglacial hydrology are processes that remain poorly known since they remain challenging to observe. Those processes are highly intermittent in time and heterogeneous in space. They thus require continuous monitoring with high spatio-temporal resolution, as proposed by the RESOLVE innovative platform, to provide new insights into targeted processes.

Objectives/Methodology

The goal is to provide finely resolved observations of glacier fracturing, basal sliding and subglacial hydrology from the use of multiple and dense geophysical sensors including seismic, radar and electrical measurements. The unprecedented insights from these observations will ultimately be used to improve physical laws implemented in theoretical ice-flow models. The geophysical instrumentation will be conducted at the Argentière Glacier (French Alps). This glacier offers unique monitoring possibilities through subglacial tunnels (drilled in bedrock) allowing direct access to the glacier base and thus a continuous, independent monitoring of water runoff and ice sliding velocities (Fig. 1). This probably makes the Argentière Glacier one of the most pertinent glacier in the world to specifically investigate the targeted processes.

Expected results

Expected results are the 3D imaging of (i) crevasses geometry, (ii) subglacial channels and (iii) glacier/bedrock interface. The coupled analysis of finely-resolved basal sliding and hydrological dynamics will allow us to quantify the complex response of glacier motion to subglacial hydrology. Finally, we will study the sensitivity of glacier dynamics to internal deformation and fracturing by the recording and localization of thousands of ice quakes from the dense seismic array.

(click on the image to extend)
Figure 1
(A) Schematic of targeted processes and existing and planned field measurements on the Argentière Glacier (Chamonix Valley, France). This site offers unique instrumentation possibilities through artificially built subglacial tunnels (in grey) in which (B) water pressure (C) flow discharge and (D) subglacial sliding measurements already exist. Instruments deployed in this project are shown by the red triangles (seismic sensors), the yellow dashed lines (electric and radar) and black stars (GPS sensors). Panel (E) shows an example of seismic record associated with glacier fracturing at Argentiere (Helmstetter et al., 2015).

Updated on 15 octobre 2020