Characterization of rock glaciers environments combining structurally-coupled and petrophysically-coupled joint inversions of electrical resistivity and seismic refraction datasets

Pavoni, Mirko; Boaga, Jacopo; Wagner, F.; Bast, Alexander; Phillips, Marcia

doi:10.1016/j.jappgeo.2023.105097

Cited by 9 publications

(11 citation statements)

References 73 publications

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“…Our observed velocity for the very shallow debris layer (0-1 m depth) differs significantly from previous refraction studies done on DCG, where velocities around 500 m/s have been observed for the debris mantle (Bucki et al, 2004;Pavoni et al, 2023), though 300 m/s has been observed as well (de Pasquale et al, 2022). Our study differs from the ones noted here in the receiver spacing, where the other studies used 3-15 m, whereas we used 0.5 and 0.3 m, allowing us to characterize the debris layer velocity as gradational and highly variable.…”

Section: Srtcontrasting

confidence: 94%

“…In contrast, active seismic exploration methods have not been widely used on DCG with thick debris cover largely because of field efficiency issues and signal‐to‐noise ratios affected by the highly attenuating debris layer. Active‐source seismic studies have been limited to ( p )‐wave refraction profiles and seismic refraction tomography (SRT), which have been shown to accurately delineate zones of pure ice from debris in ice‐cored moraines and DCG (Croce & Milana, 2002; Langston et al., 2011; Musil et al., 2002; Potter, 1972) and have been combined with electrical resistivity methods (Pavoni et al., 2023; Wagner et al., 2019). Attempts at seismic reflection studies on rock glaciers have not been as successful (Maurer & Hauck, 2007; Musil et al., 2002).…”

Section: Introductionmentioning

confidence: 99%

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Active Seismic Refraction, Reflection, and Surface‐Wave Surveys in Thick Debris‐Covered Glacial Environments

Kuehn,

Holt,

Johnson

et al. 2024

JGR Earth Surface

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Debris‐covered glaciers (DCG) and rock glaciers have been increasingly studied in recent years because of the role they play within local watersheds, glacial ablation models due to climate change, and as analogs for buried ice features on planetary bodies such as Mars. Characterizing the supraglacial debris layer is a large part of these efforts. Geophysical exploration of DCG has mostly excluded active seismic methods, with the exception of refraction studies, due to the attenuating properties of the debris cover and field survey efficiency. We evaluate the accuracy, field efficiency, and effectiveness of seismic refraction, reflection, and surface‐wave surveys for determining the elastic properties of the debris layer and any underlying layers on DCG using the Sourdough Rock Glacier in Southcentral Alaska as a test site. We provide evidence for imaging an ultra‐shallow seismic reflection from the bottom of the loose debris layer using ultra‐dense receiver arrays and compare it to ground‐penetrating radar (GPR) images taken along the same profiles. We also detail how reliable dispersion curve images can be extracted from the surface wave package of the seismic data using the multi‐channel analysis of surface waves technique, which allows for the (s)‐wave profile to be inverted for. We find this could be a valuable addition to the toolbox of future geophysical investigations on DCG.

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Section: Srtcontrasting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Active Seismic Refraction, Reflection, and Surface‐Wave Surveys in Thick Debris‐Covered Glacial Environments

Kuehn,

Holt,

Johnson

et al. 2024

JGR Earth Surface

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“…The stratigraphies recorded during drilling indicate a 3 -4 m thick layer of boulders, above a layer of fines with ice (~ 1 m), over coarse sediments with ice, and a layer of ice and/or mud with ice (Phillips et al 2023). The internal structure was confirmed by ERT, SRT, and electro-magnetic soundings (Boaga et al 2020, Pavoni et al, 2023a. In both cases, the acquisition was performed with 48 channels and 3 m spacing between electrodes/geophones.…”

Section: Real Data Case Studies: Sites Methods and Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

“…Seismic methods are one of the most frequently and earliest applied methods to investigate the near subsurface of rock glaciers (e.g., Barsch 1973), besides electrical methods such as electrical resistivity tomography (ERT; e.g., Hilbich et al 2010), induced polarization (e.g., Duvillard et al 2018 or electro-magnetic methods (e.g., Boaga et al, 2020; Pavoni et al 2023b). Recently, refraction seismic tomography (SRT; e.g., Musil et al 2002) has regained popularity, as joint-inversion algorithms provide a more detailed insight into the ice, water, rock and air composition within a rock glacier (e.g., Hauck et al 2011;Pavoni et al 2023a).SRT is a very suitable method because the refracted seismic wave travels along the ice-bearing layer at higher seismic velocities compared to the upper sediments. Usually, higher velocities in depth imply higher impedance contrast, which is the acoustic impedance Z:the product of density (𝛔) and seismic velocity (v).…”

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confidence: 99%

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Brief communication: On the potential of seismic polarity reversal to detect a thin low-velocity layer above a high-velocity layer in ice-rich rock glaciers

Boaga,

Pavoni,

Bast

et al. 2023

Preprint

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Abstract. Seismic refraction tomography is a commonly used technique to characterize rock glaciers, as the boundary between unfrozen and ice-bearing layers represents a strong impedance contrast. In several rock glaciers, we observed a reversed polarity of the waves refracted by an extended ice-bearing layer compared to direct wave arrivals. This phase change is due to the presence of a thin low-velocity, i.e. fine- to coarse-grained sediments with ice, above a thicker high-velocity ice layer. Our results are confirmed by modelling and analysis of synthetic seismograms to demonstrate that the presence of a low-velocity layer produces a polarity reversal on the seismic gather.

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The Use of Textile Electrodes for Electrical Resistivity Tomography in Periglacial, Coarse Blocky Terrain: A Comparison With Conventional Steel Electrodes

Bast,

Pavoni,

Lichtenegger

et al. 2024

Permafrost & Periglacial

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Electrical resistivity tomography (ERT) is widely used to map, characterize, and monitor the ground in alpine and periglacial environments, where coarse blocky surfaces are often ubiquitous. ERT measurements typically use conventional steel electrodes in combination with a water‐soaked sponge. However, ensuring an optimum contact resistance between the electrodes and the ground to obtain high‐quality data is often challenging and requires considerable logistical, physical, and time commitment. To overcome this, we tested a promising sand‐filled, fist‐sized conductive textile electrode. We conducted ERT measurements using both steel and textile electrodes at a landslide and two rock glaciers in the European Alps with coarse blocky surfaces and performed statistical analyses to test the accuracy and precision of the proposed textile electrodes. Our results show that the textile electrodes can be used as an alternative to the conventional steel electrodes without limitations, as they ensure good galvanic contact with the ground and accurate resistivity measurements. The use of textile electrodes also resulted in lower contact resistances, less time invested, physical and logistical advantages, and reduced risk of injury. In the future, this will enable applications such as enhanced ERT monitoring and/or faster (quasi‐3D) imaging of the interior of entire landforms.

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Characterization of rock glaciers environments combining structurally-coupled and petrophysically-coupled joint inversions of electrical resistivity and seismic refraction datasets

Cited by 9 publications

References 73 publications

Active Seismic Refraction, Reflection, and Surface‐Wave Surveys in Thick Debris‐Covered Glacial Environments

Active Seismic Refraction, Reflection, and Surface‐Wave Surveys in Thick Debris‐Covered Glacial Environments

Brief communication: On the potential of seismic polarity reversal to detect a thin low-velocity layer above a high-velocity layer in ice-rich rock glaciers

The Use of Textile Electrodes for Electrical Resistivity Tomography in Periglacial, Coarse Blocky Terrain: A Comparison With Conventional Steel Electrodes

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