Ludger Mintrop Award
Best Paper Award
The Ludger Mintrop Award is presented to the author(s) of the best paper published in Near Surface Geophysics in the calendar year preceding the award. The paper should be of high scientific standard and should represent a significant contribution to one or more of the disciplines in our Association.
The Mintrop Award consists of a certificate as well as a specially bound copy of the issue in which the pertinent paper appears
Between 1997 and 2002, the Mintrop Award referred to the Best Oral Presentation Award of the Geophysical Division.
The Ludger Mintrop Award 2018 is presented to:
Matthias Bucker and co-authors
Adrian Flores Orozco, Andreas Hordt and Andreas Kemna
For their paper ‘An analytical membrane-polarization model to predict the complex conductivity signature of immiscible liquid hydrocarbon contaminants,’ published in Near Surface Geophysics, Volume 15, issue 6, December 2017, pp 547 - 562.
Induced polarization measurements are often made to detect contaminating hydrocarbons in soils. This excellent paper presents a method for modelling the effect of liquid hydrocarbon in sediment pore space on membrane polarization, and the consequent effect on frequency-dependent induced polarization measurements. An analytical model of the pore fluids as a sequence of electrically polarized cylinders of different lengths and radii is extended by adding an additional cylinder to
represent the contaminating hydrocarbons. The results predict that conductivity magnitude and conductivity phase generally decrease with hydrocarbon saturation. The model suggests that the explanation for an observed slight increase in complex conductivity at intermediate hydrocarbon concentrations may be that the potential at the surface of non-wetting hydrocarbon droplets is larger than that at the pore wall.
Copenhagen, 11 June 2018
Previous Winners of the Ludger Mintrop Award
and his co-authors E. Diamantopoulos, A. Hordt and W. Durner
For their paper ´Relationships between soil hydraulic parameters and induced polarization spectra´, published in Near Surface Geophysics, volume 14, issue 1, February 2016, pp. 23-37.
Few geophysical methods have a clear relationship with near-surface hydraulic properties but spectral induced polarization (SIP) is increasingly used to characterize fluid flow and transport with applications in groundwater and environmental studies. This paper reports excellent SIP laboratory work to develop theoretically founded empirical relations between hydraulic properties and frequency-dependent complex impedance. These relationships are vital to interpret SIP data in hydrogeological studies and a key aspect of the present work is a sample-holder that retains the structure of unconsolidated samples in both SIP and hydraulic measurements. Thirteen samples of eight sediments with varying salinities were analysed over a frequency range from 10 mHz to 100 Hz and the results, with corresponding uncertainties, were clearly discussed. While future studies at higher frequencies often used in field measurements would be welcomed, this paper has significant impact in this important area of SIP research.
For his paper ´Is accuracy more important than precision in near-surface refraction seismology?´, published in Near Surface Geophysics, volume 13, issue 1, February 2015, pp. 1–18.
Derecke Palmer identifies the very real issue in near-surface refraction seismology of confusing model validity (accuracy) with traveltime misfit (precision), which is critically important in tomographic methods with their attendant risk of focusing purely on traveltime misfit. Furthermore, the ubiquity of non-uniqueness in refraction seismology underscores the importance of validating the starting model and not relying on a 1D velocity gradient coupled with the computing power of automated tomographic updates. As the creator of the generalised reciprocal method, Palmer provides an authoritative and insightful analysis, in which he presents a strategy to estimate model validity and the end-members of the family of data-consistent velocity models, and offers detailed examples with clear demonstrations.
Meng Heng Loke and his co-authors Torleif Dahlin and Dale F. Rucker
For their paper 'Smoothness-constrained time-lapse inversion of data from 3D resistivity surveys', published in Near Surface Geophysics, volume 12, issue 1, February 2014, pp. 5–24.
Rainwater infiltration through landfill sites presents a situation in which the distribution of groundwater fluids and pollutants are changing in both space and time. Time-lapse 3D (4D) geoelectric surveys are increasingly being used to monitor such sites and this paper describes both theory and an inversion workflow that simultaneously inverts the 4D data using a least squares (L2) approach. Roughness filters, using both L1 and L2 norms, are incorporated to smooth the modelled resistivity distributions in both spatial and temporal domains. The filters and the workflow are tested first on synthetic data to analyse the trade-off between noise robustness and resolution, and then on two real data sets with outstanding results. The authors provide solid guidance to practising geophysicists on 4D geoelectrical inversion processing in the presence of noise, which is likely to have a significant impact on near-surface monitoring in heterogeneous environments.
Carlotta Ferrara and her co-authors
V. Di Tullio, Pier Matteo Barone, Elisabetta Mattei, Sebastian Emanuel Lauro, N. Proietti, D. Capitani and Elena Pettinelli
For their paper 'Comparison of GPR and unilateral NMR for water content measurements in a laboratory scale experiment', published in Near Surface Geophysics, volume 11, issue 2, April 2013, pp. 143-153.
The coupling of ground probing radar (GPR) is affected strongly by water saturation in the near surface; a property that itself is of interest in geotechnical investigations. In this experimental account, the authors use the early-time GPR signal, which carries information from both air wave and direct body wave, to map the spatial variation of water saturation in a concrete slab through its effect on dielectric properties in the top few centimetres of the slab. The controlled variation of saturation was monitored by using a portable unilateral nuclear magnetic resonance (NMR) sensor with a similar depth of investigation. The results show a very high degree of linear correlation between the GPR and NMR signals, which is proportional to proton density, i.e., to the water content. This elegant experiment supports the novel concept of a fast, high-resolution tool for mapping relative changes in water content in a porous material at shallow depth, and suggests an independent calibration procedure to obtain absolute saturations.
Stewart Greenhalgh and his co-authors
Xu Liu and Bing Zhou
For their paper entitled ‘Velocity and attenuation dispersion relations for the effective Biot model: total-field formulation’, published in Near Surface Geophysics, volume 10, issue 3, June 2012, pp. 197–206.
In this paper, two approaches – the host phase fields and the total fields – were applied to formulate effective Biot governing equations from an original double-porosity dual-permeability model. The previously published host-phase formulation assumes that the macroscopic fluid flux of the included phase is zero, so that this term can be ignored in the equation governing conservation of momentum. The total-field formulation developed here has no such limiting assumption and gives rise to new and more general governing equations that cover the host-field approach as a special case. By computing the phase velocity and attenuation-dispersion curves of sample rocks, the authors show that the two sets of governing equations are consistent at very low frequency but for larger volume fractions of the included phase, there is a significantly increasing discrepancy in the slow P-wave as frequency increases. The slow P-wave, whilst difficult to observe, does exist and must be considered when computing the frequency-dependent reflection coefficients at an interface with a porous medium.
La Hamimu and his co-authors Jamhir Safani and Mohd Nawawi
For their paper entitled ‘Improving the accurate assessment of a shear-wave velocity reversal profile using joint inversion of the effective Rayleigh wave and multimode Love wave dispersion curves’, published in Near Surface Geophysics, volume 9, no. 1, February 2011, pp. 1–14.
This paper presents newly developed joint inversion codes of the effective Rayleigh wave and multimode Love wave dispersion curves based on modified genetic algorithms. To assess the accuracy of each inversion approach, differences between the true and the inverted shear-wave velocity profile are quantified in terms of shear-wave velocity errors. The field example shown underlines the usefulness of the approach with an added benefit for exploration in terms of improved certainty.
Franz Königer and his co-authors G. Schmitt, R. Schuhmann and C. Kottmeier
For their paper entitled “Free Line Sensing, a new method for soil moisture measurements using high-voltage power lines”, published in Near Surface Geophysics, Vol. 8, pp. 151-161.
The new ‘Free Line Sensing’ technology uses existing high-voltage power lines to detect variations in soil moisture. Measurement data demonstrate the capability of the method to monitor the integrated soil moisture of the subsurface. The resulting signal of the ‘Free Line Sensor’ strongly responds to precipitation events and the following drying of the soil. The method is of outstanding originality and shows new ways in using widespread electromagnetic fields, which are noise for other conventional methods. They are used for mapping soil moisture and are likely to be used widely.
Alexandre Bolève and his co-authors Andre Revil, J. Janod, Jean Luc Mattiuzzo and J.-J. Fry
Preferential fluid flow pathways in embankment dams imaged by self-potential tomography. Near Surface Geophysics 7, pp. 447-462.
The new method presented can handle the non-unique solutions inherent to SP-tomography and can incorporate additional constraints. It overcomes the limitations of qualitative interpretation usual encountered. Sophisticated quantitative modelling jointly with other geo-electrical methods opens up the high potential of a simple tool, neglected for a long time in the geophysical community.
For his paper: "Frequency-dependent attenuation and velocity characteristics of nano-to-micro scale, lossy, magnetite-rich materials", published in Near Surface Geophysics Vol. 6.
The paper reports the investigation of apparent complex permittivity, attenuation and propagation characteristics of a range of nano-to-micro scale quartz/magnetite mixtures, with the aim of determining how lossy magnetic minerals affect the propagation of ground-penetrating radar waves in the near-surface environment. This paper improves our understanding and use of georadar in exploration by recognising the distributions and using them to derive additional information.
Rita Deiana and her co-authors Giorgio Cassiani, Andreas Kemna, Alberto Villa, Vittorio Bruno, and Andrea Bagliani
For their paper “An experiment of non-invasive characterization of the vadose zone via water injection and cross-hole timelapse geophysical monitoring”, published in Near Surface Geophysics, Vol. 5, No 3.
An important objective of near surface geophysics is the quantitative description of (substantial) processes taking place in the subsurface. The combination of recurring high-resolution geophysical measurements and numeric modelling realized in this paper is a large step towards this goal. The presented results allow better understanding of the migration of fluids in the vadose zone.
For his paper “Imaging subsurface by seismic P-wave tomography: numerical and experimental validations”, published in Near Surface Geophysics, Vol. 4, No 5. The paper presents a method of P-wave seismic imaging based on traveltime tomography and Kirchoff migration. The method uses Fresnel wave-paths, appropriate migration and filtering to improve the imaging quality in high-contrast media. The paper shows these techniques in action on synthetic data and with a specifically designed experiment. The new approach significantly improves seismic imaging, particularly in the near surface.
Roger Wisén and his co-authors Esben Auken and Torleif Dahlin
For their paper "Combination of 1D laterally constrained inversion and 2D smooth inversion of resistivity data with a priori data from boreholes", published in Near Surface Geophysics, Vol. 3, No. 2. The authors show that the combination of 1D laterally constrained inversion and 2D smooth inversion with the use of a priori information from borehole data adds significant value to the interpretation of continuous vertical electrical sounding data. The approach to the inversion of merged data represents an especially significant achievement that should also prove valuable for the inversion of geophysical data in general.
Odile Abraham and co-authors Rabih Chammas, Philippe Cote, Helle Pedersen and Jean-François Semblat
For their paper “Mechanical characterisation of heterogeneous soils with surface waves: experimental validation on reduced scale physical models”, published in Near Surface GeophysicsVol. 2, No. 4, 249-258. The paper demonstrates very convincingly that seismic surface waves can be used to investigate strongly heterogeneous media in geo-engineering applications. It shows that the mechanical characteristics obtained from numerical propagation of surface waves in a heterogeneous medium coincide well with those predicted by a multiple scattering homogenisation technique, a conclusion validated experimentally on models. For that, the paper represents an important contribution to our further understanding of seismic surface waves and to improved application of the corresponding techniques.
Colette Gregoire and her co-authors Lucien Halleux and Volker Lukas
For their paper entitled "GPR abilities for the detection and characterisation of open fractures in a salt mine" which appeared in Near Surface Geophysics Vol. 1, No. 3. The paper provides the first reliable quantification of fracture assessment with Ground Penetrating Radar. Studies with in situ measurements, including borehole verification, are combined with synthetic data to allow the determination of fracture geometry, an inversion scheme yielding direct estimates of the openings. The work provides valuable insight into the capabilities and limitations of georadar for fracture detection and is highly relevant to the study of rock stability and tightness.