Imaging mass‐wasting sliding surfaces within complex glacial deposits along coastal cliffs using geophysics

Blondel, Simon; Uhlemann, Sebastian; Inauen, Cornelia; Watlet, Arnaud; Maurer, Hansruedi; Jordan, Colm; Lee, Jonathan; Chambers, Jonathan. 2022 Imaging mass‐wasting sliding surfaces within complex glacial deposits along coastal cliffs using geophysics. Earth Surface Processes and Landforms, 47 (9). 2310-2324. https://doi.org/10.1002/esp.5379

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Official URL: http://dx.doi.org/10.1002/esp.5379

Abstract/Summary

This study presents a multidisciplinary survey combining geological fieldwork and geophysical data to better constrain the parameters influencing the morphology and behaviour of a retreating coastal cliff. Erosion rates are spatially highly variable and hard to predict because of the manifold parameters acting on them. Among these parameters, rock resistance exerts a paramount influence on cliff retreat. Characterizing the rock resistance distribution along a coastal region requires the mapping of several key subsurface properties including the bulk lithology, faulting, fracturing, or weathering. This is a difficult and expensive task because of the high spatial variability of these factors linked to the spatial complexity of the geology. Geophysical methods can be used to tackle this challenge by quickly providing the 3D visualization and distribution of these parameters within the subsurface. A fast-eroding portion of the Norfolk coast (UK) at West Runton is investigated using a multidisciplinary approach, combining ground-penetrating radar, electrical resistivity tomography (ERT), cone penetration tests, and outcrop studies. The results allowed us to build a 3D geological and geophysical model of a highly complex area of glacial geology. It forms part of a relict glaciotectonic thrust-tip moraine and sand basin sequence. The surfaces interpreted on radar data are associated with strong resistivity contrasts on the ERT data. These contrasts have been attributed to petrophysical variations between the lithological units. The base of the sand basin is marked by a low-permeability clay bed. Its low shear strength is likely to be more susceptible to failure, hereby accelerating the erosion rate of an already fast-eroding sand basin. The resulting model can be used as input for locally constraining the ground parameters in coastal recession and erosion models.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1002/esp.5379
ISSN:	0197-9337
Date made live:	06 May 2022 09:06 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/532591

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1002/esp.5379

ISSN:

0197-9337

Date made live:

06 May 2022 09:06 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/532591