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Deep crustal electromagnetic structure of Bhuj earthquake region (India) and its implications

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dc.creator Naganjaneyulu, K.
dc.creator Ledo Fernández, Juanjo
dc.creator Queralt i Capdevila, Pilar
dc.date 2011-03-08T09:35:07Z
dc.date 2011-03-08T09:35:07Z
dc.date 2010
dc.date.accessioned 2024-12-16T10:26:15Z
dc.date.available 2024-12-16T10:26:15Z
dc.identifier 1695-6133
dc.identifier http://hdl.handle.net/2445/16884
dc.identifier 567178
dc.identifier.uri http://fima-docencia.ub.edu:8080/xmlui/handle/123456789/20783
dc.description The existence of fluids and partial melt in the lower crust of the seismically active Kutch rift basin (on the western continental margin of India) owing to underplating has been proposed in previous geological and geophysical studies. This hypothesis is examined using magnetotelluric (MT) data acquired at 23 stations along two profiles across Kutch Mainland Uplift and Wagad Uplift. A detailed upper crustal structure is also presented using twodimensional inversion of MT data in the Bhuj earthquake (2001) area. The prominent boundaries of reflection in the upper crust at 5, 10 and 20 km obtained in previous seismic reflection profiles correlate with conductive structures in our models. The MT study reveals 1-2 km thick Mesozoic sediments under the Deccan trap cover. The Deccan trap thickness in this region varies from a few meters to 1.5 km. The basement is shallow on the northern side compared to the south and is in good agreement with geological models as well as drilling information. The models for these profiles indicate that the thickness of sediments would further increase southwards into the Gulf of Kutch. Significant findings of the present study indicate 1) the hypocentre region of the earthquake is devoid of fluids, 2) absence of melt (that is emplaced during rifting as suggested from the passive seismological studies) in the lower crust and 3) a low resistive zone in the depth range of 5-20 km. The present MT study rules out fluids and melt (magma) as the causative factors that triggered the Bhuj earthquake. The estimated porosity value of 0.02% will explain 100-500 ohm·m resistivity values observed in the lower crust. Based on the seismic velocities and geochemical studies, presence of garnet is inferred. The lower crust consists of basalts - probably generated by partial melting of metasomatised garnet peridotite at deeper depths in the lithosphere - and their composition might be modified by reaction with the spinel peridotites.
dc.format 16 p.
dc.format application/pdf
dc.language eng
dc.publisher Universitat de Barcelona (UB). Institut de Ciències de la Terra Jaume Almera (ICTJA). Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDEA). Universitat Autonònoma de Barcelona (UAB). Consejo Superior de Investigaciones Científicas (CSIC)
dc.relation Reproducció del document publicat a http://doi.org/10.1344/105.000001517
dc.relation Geologica Acta, 2010, vol. 8, núm. 1, p. 83-97
dc.relation http://doi.org/10.1344/105.000001517
dc.rights cc by-sa (c) Naganjaneyulu et al., 2010
dc.rights http://creativecommons.org/licenses/by-sa/3.0/es/
dc.rights info:eu-repo/semantics/openAccess
dc.source Articles publicats en revistes (Dinàmica de la Terra i l'Oceà)
dc.subject Sismologia
dc.subject Geodinàmica
dc.subject Índia
dc.subject Seismology
dc.subject Geodynamics
dc.subject India
dc.title Deep crustal electromagnetic structure of Bhuj earthquake region (India) and its implications
dc.type info:eu-repo/semantics/article
dc.type info:eu-repo/semantics/publishedVersion


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