@article{fdi:010023108,
  title = {{I}mprovement in {TDEM} sounding interpretation in presence of induced polarization : a case study in resistive rocks of the {F}ogo volcano, {C}ape {V}erde islands},
  author = {{D}escloitres, {M}arc and {G}u{\'e}rin, {R}. and {A}lbouy, {Y}ves and {T}abbagh, {A}. and {R}itz, {M}ichel},
  editor = {},
  language = {{ENG}},
  abstract = {{A} {T}ime {D}omain {E}lectromagnetic ({TDEM}) survey was carried out in and around the caldera of the {F}ogo volcano, {C}ape {V}erde {I}slands, to detect the low resistive structures that could be related to groundwater. {A} sign reversal in the sounding curves was encountered in central-loop measurements for the soundings located in the centre of the caldera along three main radial profiles ; the negative transients are recorded in the early channels between 6.8 and 37 microseconds. {N}egative values in an early time transient is an unusual field observation, and consequently the first step was to check the data to ascertain their accuracy and quality. {I}n the second step, three dimensional (3{D}) effects are evaluated and ruled out in this zone, while an {I}nduced {P}olarization ({IP}) phenomenom is observed using {D}irect {C}urrent ({DC}) sounding measurements. {I}n the third step, the {IP} effect is called upon to explain the {TDEM} distorsions ; a {C}ole-{C}ole dispersive conductivity is necessary to explain the field data. {T}he {ID} electrical structure exhibits four layers, with decreasing resistivity with depth. {O}nly the first layer is polarizable and its {C}ole-{C}ole parameters are m=0.85, c=0.8 and {T}au=0.02 ms for chargeability, frequency dependence and time constant, respectively. {H}owever, the {C}ole-{C}ole parameters deduced from {TDEM} forward modelling remain different from those deduced from {DC}/{IP} sounding. {I}n this volcanic setting, this {IP} effet may be caused by the presence of small grains of magnetite and/or by the granularity of effusive products (lapillis). {A}s a conclusion, it is shown that a modelling using different {TDEM} data sets is essential to recover the electrical structure of this area. ({R}{\'e}sum{\'e} d'auteur)},
  keywords = {{ELECTROMAGNETISME} ; {RESISTIVITE} ; {AQUIFERE} ; {PROSPECTION} {MAGNETIQUE} ; {PROSPECTION} {ELECTRIQUE} ; {MODELISATION} ; {CAP} {VERT} ; {FOGO} {VOLCAN}},
  booktitle = {},
  journal = {{J}ournal of {A}pplied {G}eophysics},
  volume = {45},
  numero = {},
  pages = {1--18},
  ISSN = {0926-9851},
  year = {2000},
  DOI = {10.1016/{S}0926-9851(00)00015-{X}},
  URL = {https://www.documentation.ird.fr/hor/fdi:010023108},
}