Using 2D inversion of magnetic resonance soundings to locate a water-filled karst conduit

Boucher, Marie; Girard, Jean-François; Legchenko, Anatoly; Baltassat, Jean-Michel; Dörfliger, Nathalie; Chalikakis, Konstantinos

doi:10.1016/j.jhydrol.2006.03.034

Cited by 46 publications

(29 citation statements)

References 10 publications

(10 reference statements)

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“…MRS is an efficient tool not only for characterizing aquifers but also for locating water-filled voids in the subsurface (Vouillamoz et al, 2003;Boucher et al, 2006). Legchenko et al (2006a), have shown using both numerical modeling and field measurements, that the MRS can be applied to investigate the weathered part of hard-rock aquifers, when the product of the free water content multiplied by aquifer thickness is >0.2.…”

Section: The Magnetic Resonance Sounding Methods (Mrs)mentioning

confidence: 99%

Overview of the geophysical studies in the Dead Sea coastal area related to evaporite karst and recent sinkhole development

Ezersky¹,

Legchenko²,

Eppelbaum³

et al. 2017

IJS

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Abstract:Since the early 80s, a progressively increasing number of sinkholes appeared along the Dead Sea coastal line. It has been found that their appearance is strongly correlating with the lowering of the Dead Sea level taking place with the rate of approximately 1 m/yr. Location of areas affected by sinkhole development corresponds to location of the salt formation deposited during the latest Pleistocene, when the Lake Lisan receded to later become the Dead Sea. Water flowing to the Dead Sea from adjacent and underlying aquifers dissolves salt and creates caverns that cause ground subsidence and consequent formation of sinkholes. Before subsidence, these caverns are not visible on the surface but can be investigated with surface geophysical methods. For that, we applied Surface Nuclear Magnetic Resonance (SNMR), Transient Electromagnetic (TEM) Seismic refraction and reflection, Multichannel Analysis of Surface waves (MASW), microgravity and magnetic surveys and their combinations. Our geophysical results allowed us to locate the salt formation and to detect caverns in salt thus contributing to better understanding sinkhole development mechanisms. Comparison of sinkhole appearance along the western DS shore derived from the recent database (2017) shows that predictions made on the base of geophysical data (2005)(2006)(2007)(2008) are now confirmed thus demonstrating efficiency of our study. In this paper, we briefly present a summary of up to date knowledge of the geology and hydrogeology of Dead Sea basin, of the physical properties of the salt rock and the most popular models explaining mechanisms of sinkhole development. We also share our experience gained during geophysical studies carried out in the framework of national and international research projects in this area for the last 20 years.Dead Sea, evaporate karst, geophysics, sinkholes Ezersky M.G., Legchenko A., Eppelbaum L. and Al-Zoubi A., 2017. Overview of the geophysical studies in the Dead Sea coastal area related to evaporite karst and recent sinkhole development.

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Section: The Magnetic Resonance Sounding Methods (Mrs)mentioning

confidence: 99%

Overview of the geophysical studies in the Dead Sea coastal area related to evaporite karst and recent sinkhole development

Ezersky¹,

Legchenko²,

Eppelbaum³

et al. 2017

IJS

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“…In the Larzac area, where the subsurface is composed of limestone and dolomite that have low magnetic susceptibility, T Ã 2 relaxation time can be safely used. In carbonate rocks, typical values of the relaxation time T Ã 2 range from 80 to 130 ms in the absence of large or multiple karst voids ( Miehé et al, 2003;Boucher et al, 2006b). Otherwise, it is generally higher than 400 ms Vouillamoz et al, 2003).…”

Section: Hydrogeological Interpretation Of Mrs Resultsmentioning

confidence: 99%

“…The MRS method was initially developed for characterizing the saturated zone. Most MRS applications on karst systems (e.g., Vouillamoz et al, 2003;Boucher et al, 2006b;Girard et al, 2007;Legchenko et al, 2008a;Pérez-Bielsa et al, 2012) have thus been devoted to the investigation of saturated zone properties. However, water can be detected in the unsaturated zone in weakly magnetic environments, e.g., in carbonate rocks or in sandy formations Miehé et al, 2003;Lubczynski and Roy, 2005;Boucher et al, 2006a;Vouillamoz et al, 2012;Costabel and Gunther, 2014;Walsh et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Contribution of magnetic resonance soundings for characterizing water storage in the unsaturated zone of karst aquifers

et al. 2016

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Understanding the role of the unsaturated zone in aquifer recharge and contaminant attenuation processes is a major challenge for the protection and management of karstic water resources. We present the potential of the magnetic resonance soundings (MRS) geophysical method for characterizing the vadose zone of karst aquifers composed of epikarst and infiltration layers. To investigate the hydraulic functioning of the Durzon karst system located on the Larzac plateau (southern France), we used the MRS method at 16 sites. The MRS results have been compared with available geologic information and to core water content measurements. The remarkable spatial variability of the MRS response observed in the study area makes it possible to determine ranges of water storage properties in relation to the lithology of the investigated carbonate formations (dolomite, marly, and siliceous limestone). All soundings found either constant or increasing MRS water content with depth, which demonstrates that the infiltration zone might be the major water storage entity for permanent water storage, with important consequences for recharge quality and quantity. These results show the feasibility and potential of the MRS method for the characterization of the karst unsaturated zone and for understanding the vertical distribution of water content, which impacts the overall functioning of karst systems.

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“…Cette méthode géophysique est utilisée habituellement dans le domaine de la recherche d'eau souterraine (Legchenko et Valla, 2002 ;Boucher et al, 2006 ;Girard et al 2007). Elle permet la détection directe de l'eau liquide par des sondages non destructifs réalisés depuis la surface.…”

Section: Detection D'un Volume De 65 000 M 3 D'eau En 2009 Et 20unclassified

Détection d’une poche d’eau au glacier de Tête Rousse en 2010 et mesures préventives pour éviter une catastrophe

et al. 2012

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RÉSUMÉ. -Entre 2009 et 2010, une poche d'eau d'un volume d'environ 65000 m3 a été détectée dans le glacier de Tête Rousse grâce à une combinaison de méthodes géophysiques mises en oeuvre conjointement par trois laboratoires grenoblois (LGGE, ISTerre-ex LGIT et LTHE). C'est la première fois qu'une poche d'eau intra-glaciaire de cette importance est ainsi détectée dans un glacier alpin avant une rupture. Cette poche représentait une menace pour St Gervais, avec un volume à peu près équivalent à celui qui avait provoqué la catastrophe de 1892 (175 morts). Trois mille personnes étaient potentiellement menacées en 2010. Nous avons alors alerté les autorités publiques le 13 juillet 2010 et préconisé la vidange artificielle de cette poche d'eau. Des décisions immédiates ont conduit à des opérations de pompage entre août et octobre 2010. Nous présentons ici les méthodes géophysiques qui ont permis de détecter cette poche ainsi que l'analyse de l'aléa d'une vidange brutale. Enfin, nous analysons le régime thermique du glacier qui constitue la cause de la rétention de l'eau sous glaciaire. Mots clefs : poche d'eau, tête rousse, vidange, glacier Intraglacial water reservoir detected from a geophysical survey in 2010and preventive measures to avoid a disaster ABSTRACT. -In 2009 and2010, an intraglacial water reservoir of about 65000 m3 has been detected from a geophysical survey using ground penetrating radar measurements, surface nuclear magnetic resonance imaging and boreholes, carried out by 3 labs of Grenoble. It was the first time that an intraglacial water reservoir was detected in an alpine glacier before an outburst flood. The 1892 outburst flood, from an intraglacial water reservoir in the same glacier, killed 175 people in the town of Saint Gervais. 3000 inhabitants were threatened in 2010. We warned the authorities in charge of public safety (Prefecture de haute Savoie) on 13 July 2010. Immediate action was therefore taken and the subglacial lake was drained artificially using down-hole pumps between August and October 2010. Our ice temperature measurements show clearly the cause of the water accumulation inside the glacier.

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Using 2D inversion of magnetic resonance soundings to locate a water-filled karst conduit

Cited by 46 publications

References 10 publications

Overview of the geophysical studies in the Dead Sea coastal area related to evaporite karst and recent sinkhole development

Overview of the geophysical studies in the Dead Sea coastal area related to evaporite karst and recent sinkhole development

Contribution of magnetic resonance soundings for characterizing water storage in the unsaturated zone of karst aquifers

Détection d’une poche d’eau au glacier de Tête Rousse en 2010 et mesures préventives pour éviter une catastrophe

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