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Combining multiple signals of an electromagnetic induction sensor to prospect land for metal objects

Timothy Saey UGent, Marc Van Meirvenne UGent, M Dewilde, F Wyffels, Philippe De Smedt UGent, Eef Meerschman UGent, Mohammad Monirul Islam UGent, Fun Meeuws UGent and Liesbet Cockx UGent (2011) NEAR SURFACE GEOPHYSICS. 9(4). p.309-317
abstract
Buried unexploded ammunition is a major problem on arable land in former battle areas. Many battlefields of the First World War (WWI) still contain a lot of unexploded shells just below the plough layer, posing serious threats to soil editors and trenchers. Electromagnetic induction (EMI) sensors have been used for a variety of agricultural and archaeological purposes to map the natural soil variability and to locate buried archaeological remains. Besides its sensitivity to variations in soil texture and anthropogenic disturbances, EMI proves to respond strongly to metal objects in the soil. Most EMI sensors rely on a single signal, with magnitude and sign of the metal anomalies differing according to the instruments coil distance and separation. The multi-coil EMI sensor, the DUALEM-21S, provides four simultaneous apparent electrical conductivity (ECa) signals enhancing significantly the possibilities for signal processing. To calibrate our instrument, we buried different masses of metal at different depths. The four ECa measurements showed a response to the metal objects down to 1.2 m. The measurements were subtracted by their gradual trend to obtain the local anomalies (Delta ECa). A combination of these four Delta ECa's was used to amplify the signal response to metal, influenced by both depth and mass of the buried objects. At an intensively shelled former WWI battle field near Ypres (Belgium), a detailed prospection was conducted with the DUALEM-21S. Based on our multi-signal procedure, we located 40 positions, 20 where we predicted buried metal and 20 where we expected that no metal was present within 1.2 m depth. There were no false negative predictions and at the 20 locations where we expected metal, shells up to 90 kg were excavated. As a final outcome we produced a map with predictions of the mass of metal objects in the soil assuming a fixed depth and alternatively a map with predictions of the depth of metal objects assuming a given mass. Apart from their potential for agricultural and archaeological investigations, multi-ECa signals were shown to be useful for locating metal objects, like unexploded WWI shells, in the top 1.2 m of soil.
Please use this url to cite or link to this publication:
author
organization
year
type
journalArticle (original)
publication status
published
subject
journal title
NEAR SURFACE GEOPHYSICS
Near Surf. Geophys.
volume
9
issue
4
pages
309 - 317
Web of Science type
Article
Web of Science id
000300855500001
JCR category
GEOCHEMISTRY & GEOPHYSICS
JCR impact factor
0.945 (2011)
JCR rank
49/76 (2011)
JCR quartile
3 (2011)
ISSN
1569-4445
DOI
10.3997/1873-0604.2010070
language
English
UGent publication?
yes
classification
A1
copyright statement
I have transferred the copyright for this publication to the publisher
id
1888105
handle
http://hdl.handle.net/1854/LU-1888105
date created
2011-08-12 09:28:16
date last changed
2012-09-28 14:15:09
@article{1888105,
  abstract     = {Buried unexploded ammunition is a major problem on arable land in former battle areas. Many battlefields of the First World War (WWI) still contain a lot of unexploded shells just below the plough layer, posing serious threats to soil editors and trenchers. Electromagnetic induction (EMI) sensors have been used for a variety of agricultural and archaeological purposes to map the natural soil variability and to locate buried archaeological remains. Besides its sensitivity to variations in soil texture and anthropogenic disturbances, EMI proves to respond strongly to metal objects in the soil. Most EMI sensors rely on a single signal, with magnitude and sign of the metal anomalies differing according to the instruments coil distance and separation. The multi-coil EMI sensor, the DUALEM-21S, provides four simultaneous apparent electrical conductivity (ECa) signals enhancing significantly the possibilities for signal processing. To calibrate our instrument, we buried different masses of metal at different depths. The four ECa measurements showed a response to the metal objects down to 1.2 m. The measurements were subtracted by their gradual trend to obtain the local anomalies (Delta ECa). A combination of these four Delta ECa's was used to amplify the signal response to metal, influenced by both depth and mass of the buried objects. At an intensively shelled former WWI battle field near Ypres (Belgium), a detailed prospection was conducted with the DUALEM-21S. Based on our multi-signal procedure, we located 40 positions, 20 where we predicted buried metal and 20 where we expected that no metal was present within 1.2 m depth. There were no false negative predictions and at the 20 locations where we expected metal, shells up to 90 kg were excavated. As a final outcome we produced a map with predictions of the mass of metal objects in the soil assuming a fixed depth and alternatively a map with predictions of the depth of metal objects assuming a given mass. 
Apart from their potential for agricultural and archaeological investigations, multi-ECa signals were shown to be useful for locating metal objects, like unexploded WWI shells, in the top 1.2 m of soil.},
  author       = {Saey, Timothy and Van Meirvenne, Marc and Dewilde, M and Wyffels, F and De Smedt, Philippe and Meerschman, Eef and Islam, Mohammad Monirul and Meeuws, Fun and Cockx, Liesbet},
  issn         = {1569-4445},
  journal      = {NEAR SURFACE GEOPHYSICS},
  language     = {eng},
  number       = {4},
  pages        = {309--317},
  title        = {Combining multiple signals of an electromagnetic induction sensor to prospect land for metal objects},
  url          = {http://dx.doi.org/10.3997/1873-0604.2010070},
  volume       = {9},
  year         = {2011},
}

Chicago
Saey, Timothy, Marc Van Meirvenne, M Dewilde, F Wyffels, Philippe De Smedt, Eef Meerschman, Mohammad Monirul Islam, Fun Meeuws, and Liesbet Cockx. 2011. “Combining Multiple Signals of an Electromagnetic Induction Sensor to Prospect Land for Metal Objects.” Near Surface Geophysics 9 (4): 309–317.
APA
Saey, T., Van Meirvenne, M., Dewilde, M., Wyffels, F., De Smedt, P., Meerschman, E., Islam, M. M., et al. (2011). Combining multiple signals of an electromagnetic induction sensor to prospect land for metal objects. NEAR SURFACE GEOPHYSICS, 9(4), 309–317.
Vancouver
1.
Saey T, Van Meirvenne M, Dewilde M, Wyffels F, De Smedt P, Meerschman E, et al. Combining multiple signals of an electromagnetic induction sensor to prospect land for metal objects. NEAR SURFACE GEOPHYSICS. 2011;9(4):309–17.
MLA
Saey, Timothy, Marc Van Meirvenne, M Dewilde, et al. “Combining Multiple Signals of an Electromagnetic Induction Sensor to Prospect Land for Metal Objects.” NEAR SURFACE GEOPHYSICS 9.4 (2011): 309–317. Print.