Landslide monitoring using seismic refraction tomography – The importance of incorporating topographic variations

J. S. Whiteley*, J. E. Chambers, S. Uhlemann, J. Boyd, M. O. Cimpoiasu, J. L. Holmes, C. M. Inauen, A. Watlet, L. R. Hawley-Sibbett, C. Sujitapan, R. T. Swift, J. M. Kendall

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Seismic refraction tomography provides images of the elastic properties of subsurface materials in landslide settings. Seismic velocities are sensitive to changes in moisture content, which is a triggering factor in the initiation of many landslides. However, the application of the method to long-term monitoring of landslides is rarely used, given the challenges in undertaking repeat surveys and in handling and minimizing the errors arising from processing time-lapse surveys. This work presents a simple method and workflow for producing a reliable time-series of inverted seismic velocity models. This method is tested using data acquired during a recent, novel, long-term seismic refraction monitoring campaign at an active landslide in the UK. Potential sources of error include those arising from inaccurate and inconsistent determination of first-arrival times, inaccurate receiver positioning, and selection of inappropriate inversion starting models. At our site, a comparative analysis of variations in seismic velocity to real-world variations in topography over time shows that topographic error alone can account for changes in seismic velocity of greater than ±10% in a significant proportion (23%) of the data acquired. The seismic velocity variations arising from real material property changes at the near-surface of the landslide, linked to other sources of environmental data, are demonstrated to be of a similar magnitude. Over the monitoring period we observe subtle variations in the bulk seismic velocity of the sliding layer that are demonstrably related to variations in moisture content. This highlights the need to incorporate accurate topographic information for each time-step in the monitoring time-series. The goal of the proposed workflow is to minimize the sources of potential errors, and to preserve the changes observed by real variations in the subsurface. Following the workflow produces spatially comparable, time-lapse velocity cross-sections formulated from disparate, discretely-acquired datasets. These practical steps aim to aid the use of the seismic refraction tomography method for the long-term monitoring of landslides prone to hydrological destabilization.

Original languageEnglish
Article number105525
JournalEngineering Geology
Volume268
Early online date14 Feb 2020
DOIs
Publication statusPublished - Apr 2020

Bibliographical note

Funding Information:
The authors would like to acknowledge Florian Wagner for advice on the pyGIMLi API. We would also like to acknowledge members, students and visiting scholars of the BGS' Geophysical Tomography team for their input and support. We would like to thank Josie Gibson, Frances Standen and James Standen for their continued support of our monitoring activities at Hollin Hill. This work was funded by a NERC GW4+ UK Doctoral Training Partnership Studentship (Grant NE/L002434/1) and in part by the BGS University Funding Initiative (S337), which are gratefully acknowledged. Jim Whiteley, Jonathan Chambers, Jimmy Boyd, Mihai Cimpoiasu, Jessica Holmes, Cornelia Inauen, Arnaud Watlet, Luke Hawley-Sibbett and Russell Swift publish with the permission of the Executive Director, British Geological Survey (UKRI-NERC). All content generated as part of this work is copyright of British Geological Survey ? UKRI 2020/The University of Bristol 2020.

Funding Information:
The authors would like to acknowledge Florian Wagner for advice on the pyGIMLi API. We would also like to acknowledge members, students and visiting scholars of the BGS' Geophysical Tomography team for their input and support. We would like to thank Josie Gibson, Frances Standen and James Standen for their continued support of our monitoring activities at Hollin Hill. This work was funded by a NERC GW4+ UK Doctoral Training Partnership Studentship (Grant NE/L002434/1 ) and in part by the BGS University Funding Initiative ( S337 ), which are gratefully acknowledged. Jim Whiteley, Jonathan Chambers, Jimmy Boyd, Mihai Cimpoiasu, Jessica Holmes, Cornelia Inauen, Arnaud Watlet, Luke Hawley-Sibbett and Russell Swift publish with the permission of the Executive Director, British Geological Survey (UKRI-NERC). All content generated as part of this work is copyright of British Geological Survey © UKRI 2020/The University of Bristol 2020.

Publisher Copyright:
© 2020

Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

Keywords

  • Active landslides
  • Geophysical monitoring
  • Hydrogeophysics
  • Seismic refraction
  • Topographic change

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Geology

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