Seismic anisotropy analysis at the Low-Noise Underground Laboratory (LSBB) of Rustrel (France)

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La vallée de l'Halil Roud (région de Jiroft, Iran) : étude géoarchéologique, méthodologie et résultats préliminaires

Abstract : The Jiroft area, located in a semi-arid zone along the Halil Rud in southeastern Iran, seems to have been an important cultural center during the 3rd millennium ВС. This paper presents the preliminary results of the first two years (2004 and 2005) of a geoarchae- ological program carried out at the invitation of Prof. Madjidzadeh. The Quaternary geomorphological dynamics in the valley are studied, and we present the preliminary results of a geophysical prospection (electro-magnetism, seismic refraction, radar) carried out in January 2005. Climatic aridity, seismicity and large, sudden floods are the most important risks for human societies in the Jiroft basin. Artesian wells and abundant phreatic water are of primary importance for human settlements even though the water is salty. The reconstruction ofpaleoalluvialfans and fossil riverbeds under several meters ofHolocene deposits, should come first in our attempt to understand the paleogeography of the valley.Résumé : La région de Jiroft, située le long de la vallée de l'Halil Roud au sud-est de l'Iran, en domaine semi-aride, semble avoir été un foyer culturel important au IIIe millénaire avant J.-C. Nous présentons les résultats des deux premières années (2004 et 2005) d'un programme géoarchéologique réalisé à l 'invitation du professeur Madjidzadeh. Nous étudions les dynamiques géomorphologiques à l'œuvre dans la vallée depuis le début du Quaternaire et présentons les résultats préliminaires d'une prospection géophysique (électromagnétisme, sismique réfraction, radar) réalisée en janvier 2005 sur le site archéologique de Konar Sandal Sud. L 'aridité climatique, l 'aléa sismique et les crues brutales sont les contraintes récurrentes qui pèsent sur toute implantation humaine dans cette région. En revanche, la présence de puits artésiens et d'une nappe phréatique abondante, proche de la surface, ont constitué un atout inestimable malgré une salinité élevée. La reconstitution des emboîtements de terrasses fluviatiles, la recherche des lits fluviaux fossilisés sous plusieurs mètres d 'alluvions holocènes sont une priorité pour reconstituer la paléo-topographie de la région.Fouache Eric, Garçon Damien, Rousset Dominique, Sénéchal Guy, Madjidzadeh Youssef. La vallée de l'Halil Roud (région de Jiroft, Iran) : étude géoarchéologique, méthodologie et résultats préliminaires . In: Paléorient, 2005, vol. 31, n°2. pp. 107-122

Full-waveform inversion of GPR data acquired between boreholes in Rustrel carbonates

Full waveform inversion (FWI) of seismic or Ground Penetrating Radar data provides high-resolution quantitative images of the constitutive parameters of the rock/soil which control seismic/GPR wave propagation. We developed a 2D inversion tool in the frequency domain adapted to the multi-parameter physics controlling GPR propagation in isotropic non dispersive media, i.e. dielectric permittivity and electrical conductivity. This inversion engine was previously tested using synthetic 2D data to mitigate the trade-off between the two parameter classes. In this paper, we present the required processing techniques and first inversion results obtained on a real GPR dataset acquired in carbonates with a cross-hole configuration. The presence of the 2 m diameter underground gallery at depth constitutes a nice target to test the robustness, efficiency and resolution of the inversion in such high-contrasts context. Starting from a time tomographic image for the dielectric permittivity and from a homogeneous conductivity, we show that FWI is efficient to retrieve high resolution images of dielectric permittivity but struggles with electrical conductivity. As a quality control, we compare real and synthetic radargrams computed from the tomography and final images, showing the efficiency of the process to reconstruct some events but also underlying some issues, particularly on large incidence angles amplitude traces

Carl Bouchard : Se voir en amour

Sénéchal and Blackburn examine the materials and devices in Bouchard’s work which, according to Sénéchal, “put(s) the concept of love on trial.” These texts are followed by the transcription of an email exchange between M. LaChance and J-E Joos (which includes a reply by Bouchard), commenting on the artist’s interdisciplinary works. Brief biographical notes on artist and authors. List of works. 6 bibl. ref