@article{fdi:010073149,
  title = {3{D} electrical conductivity tomography of volcanoes},
  author = {{A}hmed, {A}. {S}. and {R}evil, {A}. and {B}yrdina, {S}vetlana and {C}operey, {A}. and {G}ailler, {L}. and {G}robbe, {N}. and {V}iveiros, {F}. and {S}ilva, {C}. and {J}ougnot, {D}. and {G}horbani, {A}. and {H}ogg, {C}. and {K}iyan, {D}. and {R}ath, {V}. and {H}eap, {M}. {J}. and {G}randis, {H}. and {H}umaida, {H}.},
  editor = {},
  language = {{ENG}},
  abstract = {{E}lectrical conductivity tomography is a well-established galvanometric method for imaging the subsurface electrical conductivity distribution. {W}e characterize the conductivity distribution of a set of volcanic structures that are different in terms of activity and morphology. {F}or that purpose, we developed a large-scale inversion code named {ECT}-3{D} aimed at handling complex topographical effects like those encountered in volcanic areas. {I}n addition, {ECT}-3{D} offers the possibility of using as input data the two components of the electrical field recorded at independent stations. {W}ithout prior information, a {G}auss-{N}ewton method with roughness constraints is used to solve the inverse problem. {T}he roughening operator used to impose constraints is computed on unstructured tetrahedral elements to map complex geometries. {W}e first benchmark {ECT}-3{D} on two synthetic tests. {A} first test using the topography of {M}t. {S}t {H}elens volcano ({W}ashington, {USA}) demonstrates that we can successfully reconstruct the electrical conductivity field of an edifice marked by a strong topography and strong variations in the resistivity distribution. {A} second case study is used to demonstrate the versatility of the code in using the two components of the electrical field recorded on independent stations along the ground surface. {T}hen, we apply our code to real data sets recorded at (i) a thermally active area of {Y}ellowstone caldera ({W}yoming, {USA}), (ii) a monogenetic dome on {F}umas volcano (the {A}zores, {P}ortugal), and (iii) the upper portion of the caldera of {K}ilauea ({H}awaii, {USA}). {T}he tomographies reveal some of the major structures of these volcanoes as well as identifying alteration associated with high surface conductivities. {W}e also review the petrophysics underlying the interpretation of the electrical conductivity of fresh and altered volcanic rocks and molten rocks to show that electrical conductivity tomography cannot be used as a stand-alone technique due to the non-uniqueness in interpreting electrical conductivity tomograms. {T}hat said, new experimental data provide evidence regarding the strong role of alteration in the vicinity of preferential fluid flow paths including magmatic conduits and hydrothermal vents.},
  keywords = {},
  booktitle = {},
  journal = {{J}ournal of {V}olcanology and {G}eothermal {R}esearch},
  volume = {356},
  numero = {},
  pages = {243--263},
  ISSN = {0377-0273},
  year = {2018},
  DOI = {10.1016/j.jvolgeores.2018.03.017},
  URL = {https://www.documentation.ird.fr/hor/fdi:010073149},
}