@article{fdi:010055964,
  title = {{E}stimation of the near-surface velocity structure of the {Y}asur-{Y}enkahe volcanic complex, {V}anuatu},
  author = {{P}errier, {L}. and {M}{\'e}taxian, {J}ean-{P}hilippe and {B}attaglia, {J}. and {G}araebiti, {E}.},
  editor = {},
  language = {{ENG}},
  abstract = {{S}mall-aperture array measurements of seismic noise at seven sites around {Y}asur volcano ({V}anuatu) are performed to estimate the {V}-{P} and {V}-{S} velocities of the shallow structure. {T}he spatial autocorrelation ({SPAC}) and the frequency-wavenumber (f-k) methods are used to determine {R}ayleigh phase velocity dispersion curves. {P}hase velocities computed with the {SPAC} method vary between 580 m/s and 960 m/s at 1 {H}z and between 270 m/s and 420 m/s at 15 {H}z. {F}-k dispersion curves show velocities of 300-340 m/s and 800-940 m/s at 1 {H}z and 200-230 m/s at 15 {H}z. {A}n inversion technique based on the use of the neighbourhood algorithm has been used to calculate the one-dimensional velocity model at each site. {V}elocity models reach 200 m deep and mainly contain two layers and a half-space. {F}or sites close to the {S}iwi caldera rims, comparisons with geology and hydrothermal system studies suggest that the two layers highlighted in models may correspond to two large pyroclastic sequences related to caldera collapses based on the flank of an old volcano. {R}esults obtained for the other three sites, located inside the caldera, show the influence of the hydrothermal system on {P}- and {S}-wave velocities. {F}or these sites, fluid circulation inside the volcanic deposits causes lower velocities at depth. {T}o obtain a near-surface velocity model of the volcanic structure, each 1{D} velocity model is spatially extrapolated according to the surface geology. {R}esults highlight four distinct areas, the {S}iwi caldera edges with high velocities and the resurgent block, the ash plain and the {Y}asur edifice with lower velocities at depth.},
  keywords = {{V}olcano seismology ; {V}elocity structure ; {SPAC} method ; f-k method ; {Y}asur volcano},
  booktitle = {},
  journal = {{J}ournal of {V}olcanology and {G}eothermal {R}esearch},
  volume = {227},
  numero = {},
  pages = {50--60},
  ISSN = {0377-0273},
  year = {2012},
  DOI = {10.1016/j.jvolgeores.2011.12.006},
  URL = {https://www.documentation.ird.fr/hor/fdi:010055964},
}