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Titre du document / Document title

An analysis of magnetotelluric (MT) data over geothermal region of Bakreshwar, West Bengal

Auteur(s) / Author(s)

SINHARAY Rajib K. (1) ; SHALIVAHAN (1) ; BHATTACHARYA Bimalendu B. (1) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Department of Applied Geophysics, Indian School of Mines, Dhanbad - 826004, INDE

Résumé / Abstract

Magnetotelluric (MT) reconnaissance survey has been carried out over the geothermal region of Bakreshwar, West Bengal to study the resistivity, strike direction and dimensionality of the subsurface conductivity structure. This paper is an effort to get most from the already acquired data before planning for more data. The results of sequential analysis of polar diagrams, Swift's strike, rotation angle, tipper magnitude and skew have been presented for three MT soundings: (1) 500 m NE, (2) 1.2 km SW and (3) 9 km away in NE direction from the hot spring respectively. 1-D models have been prepared by very fast simulated annealing (VFSA), a nonlinear inversion technique, for both transverse electric (TE) and transverse magnetic (TM) modes and their resolutions at different depths have been compared. The nearest sounding to the hot spring shows two low resistive zones of about 100 ohm-m and 15 ohm-m at a depth of about 8 km and 12 km respectively in TM mode. The thicknesses of these two low resistive zones are 2.3 km and 3.4 km respectively. These zones, however, are local in nature as they are not seen even in the sounding 1.2 km away on the other side of the hot spring. It is seen that the TM mode gives better resolution at shallower depths than TE mode. Tipper and skew parameters indicate that near surface structure is 1-D or 2-D in nature but for larger depths it is 3-D in nature.

Revue / Journal Title

Journal of geophysics    ISSN  2230-9497 

Source / Source

2001, vol. 22, no1, pp. 31-39 (10 ref.)

Langue / Language

Anglais

Editeur / Publisher

Association of Exploration Geophysicists, Hyderabad, INDE  (1997) (Revue)

Mots-clés anglais / English Keywords

Bengal

;

magnetotelluric sounding

;

geothermal systems

;

direction

;

conductivity

;

rotation

;

magnitude

;

hot springs

;

depth

;

electrical resistivity

;

electrical conductivity

;

one-dimensional models

;

inverse problem

;

impedance

;

apparent resistivity

;

Indian Peninsula

;

Asia

;

Mots-clés français / French Keywords

Bengale

;

Sondage magnétotellurique

;

Système géothermique

;

Direction

;

Conductivité

;

Rotation

;

Magnitude

;

Source thermale

;

Profondeur

;

Résistivité électrique

;

Conductivité électrique

;

Modèle 1 dimension

;

Problème inverse

;

Impédance

;

Résistivité apparente

;

Péninsule Indienne

;

Asie

;

Mots-clés espagnols / Spanish Keywords

Sistema geotérmico

;

Dirección

;

Rotación

;

Magnitud

;

Fuente termal

;

Profundidad

;

Resistividad eléctrica

;

Conductividad eléctrica

;

Modelo 1 dimensión

;

Problema inverso

;

Península India

;

Asia

;

Localisation / Location

INIST-CNRS, Cote INIST : 20057, 35400009928871.0050

Nº notice refdoc (ud4) : 1145977



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