Predicting the movements of permanently installed electrodes on an active landslide using time‐lapse geoelectrical resistivity data only

If electrodes move during geoelectrical resistivity monitoring and their new positions are not incorporated in the inversion, then the resulting tomographic images exhibit artefacts that can obscure genuine time-lapse resistivity changes in the subsurface. The effects of electrode movements on time-lapse resistivity tomography are investigated using a simple analytical model and real data. The correspondence between the model and the data is sufficiently good to be able to predict the effects of electrode movements with reasonable accuracy. For the linear electrode arrays and 2D inversions under consideration, the data are much more sensitive to longitudinal than transverse or vertical movements. Consequently the model can be used to invert the longitudinal offsets of the electrodes from their known baseline positions using only the time-lapse ratios of the apparent resistivity data. The example datasets are taken from a permanently installed electrode array on an active lobe of a landslide. Using two sets with different levels of noise and subsurface resistivity changes, it is found that the electrode positions can be recovered to an accuracy of 4 % of the baseline electrode spacing. This is sufficient to correct the artefacts in the resistivity images, and provides for the possibility of monitoring the movement of the landslide and its internal hydraulic processes simultaneously using electrical resistivity tomography only.

[1]  V. Lapenna,et al.  High-resolution electrical imaging of the Varco d'Izzo earthflow (southern Italy) , 2004 .

[2]  R. Barker.  Depth of investigation of collinear symmetrical four-electrode arrays , 1989 .

[3]  Abelardo Ramirez,et al.  Electrical imaging at the large block test—Yucca Mountain, Nevada , 2001 .

[4]  A. Adler,et al.  Reconstruction of conductivity changes and electrode movements based on EIT temporal sequences , 2008, Physiological measurement.

[5]  William H. Press,et al.  Numerical recipes in C. The art of scientific computing , 1987 .

[6]  J. Gisbert,et al.  Automated monitoring of coastal aquifers with electrical resistivity tomography , 2009 .

[7]  J. E. Szymanski,et al.  The effect of terrain topography on commonly used resistivity arrays , 1999 .

[8]  T. Dahlin,et al.  Properties and Effects of Measurement Errors on 2D Resistivity Imaging Surveying , 2003 .

[9]  R. Pallas-Areny,et al.  Noniterative algorithms for electrical resistivity imaging applied to subsurface local anomalies , 2005, IEEE Sensors Journal.

[10]  Birgit Jochum,et al.  A complex geo-scientific strategy for landslide hazard mitigation – from airborne mapping to ground monitoring , 2008 .

[11]  E. Tric,et al.  Geophysical survey to estimate the 3D sliding surface and the 4D evolution of the water pressure on part of a deep seated landslide , 2005 .

[12]  B H Blott,et al.  Electrical impedance tomography with compensation for electrode positioning variations. , 1998, Physics in medicine and biology.

[13]  D. Varnes,et al.  Landslide types and processes , 2004 .

[14]  S. Friedel,et al.  Investigation of a slope endangered by rainfall-induced landslides using 3D resistivity tomography and geotechnical testing , 2006 .

[15]  Andy Adler,et al.  Direct EIT Jacobian calculations for conductivity change and electrode movement , 2008, Physiological measurement.

[16]  V. Lapenna,et al.  Integrated geophysical and geomorphological approach to investigate the snowmelt-triggered landslide of Bosco Piccolo village (Basilicata, southern Italy) , 2008 .

[17]  D. Jongmans,et al.  Geophysical investigation of landslides : a review , 2007 .

[18]  T. Glade,et al.  Comparison of GPR, 2D-resistivity and traditional techniques for the subsurface exploration of the Öschingen landslide, Swabian Alb (Germany) , 2008 .

[19]  J. Chatelain,et al.  Application of geophysical methods for the investigation of the large gravitational mass movement of Sechilienne, France , 2005 .

[20]  Koichi Suzuki,et al.  Groundwater flow after heavy rain in landslide-slope area from 2-D inversion of resistivity monitoring data , 2001 .

[21]  Ping Wang,et al.  Using genetic algorithm for electrode movement problem in Electrical Impedance Tomography , 2008, 2008 World Automation Congress.

[22]  Philip I. Meldrum,et al.  Hydrogeophysical monitoring of landslide processes using automated time-lapse electrical resistivity tomography (ALERT) [extended abstract] , 2009 .

[23]  D. Parasnis,et al.  Reciprocity theorems in geoelectric and geoelectromagnetic work , 1988 .

[24]  L. Milano,et al.  Electrical resistivity tomography and statistical analysis in landslide modelling: A conceptual approach , 2009 .

[25]  William H. Press,et al.  Numerical recipes in C (2nd ed.): the art of scientific computing , 1992 .

[26]  T. Dahlin,et al.  A comparison of smooth and blocky inversion methods in 2D electrical imaging surveys , 2001 .

[27]  E. Tric,et al.  Characterization of an internal slope movement structure by hydrogeophysical surveying , 2007 .

[28]  L. Bentley,et al.  Low temperature dependence of electrical resistivity: Implications for near surface geophysical monitoring , 2007 .

[29]  Partha S. Routh,et al.  Sensitivity of electrical resistivity tomography data to electrode position errors , 2005 .

[30]  William H. Press,et al.  Book-Review - Numerical Recipes in Pascal - the Art of Scientific Computing , 1989 .

[31]  A. Binley,et al.  DC Resistivity and Induced Polarization Methods , 2005 .

[32]  Jie Zhang,et al.  EIT images of ventilation: what contributes to the resistivity changes? , 2005, Physiological measurement.

[33]  D. Patella.  Introduction to ground surface self‐potential tomography , 1997 .

[34]  M. Soleimani,et al.  Imaging of conductivity changes and electrode movement in EIT , 2006, Physiological measurement.

[35]  J. Pritchard,et al.  Monitoring hydraulic processes with automated time-lapse electrical resistivity tomography (ALERT) , 2009 .

[36]  M. Lelliott,et al.  Extreme sensitivity of crosshole electrical resistivity tomography measurements to geometric errors , 2008 .

[37]  G. E. Archie.  The electrical resistivity log as an aid in determining some reservoir characteristics , 1942 .

[38]  V. Lapenna,et al.  2D electrical resistivity imaging of some complex landslides in the Lucanian Apennine chain, southern Italy , 2005 .