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

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 fluidsand 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.

Local perception and use of the multifunctionality of water tanks in two villages of Tamil Nadu, South India

Using data from free listings and a survey in two villages of Tamil Nadu, India, we discuss local perceptions and uses of water tanks, a traditional irrigation infrastructure. We hypothesize that both farmers and nonfarmers perceive and use water tanks for purposes other than irrigation. We found that informants recognized the importance of water tanks for irrigation, but also acknowledged other socioeconomic uses and ecological functions. Marginal sectors (i.e., Scheduled Castes) use tank resources in more diverse ways than other sectors of the population. Findings are relevant for development. International organizations working on the revival of water tanks aim to transfer water management to farmers for the purpose of irrigation. By recognizing that tanks benefit people other than farmers and in ways other than providing irrigation water, organizations working on tank rejuvenation could achieve a more equitable management of tank resources.

La formació d'una política exterior per a l'Índia. La visita de Nehru a l'Espanya republicana durant la Guerra Civil

L'objectiu ha estat posar en relació dues realitats que fins al moment havien estat considerades completament alienes, com són l’Índia i Espanya. La recerca de fonts per a les relacions bilaterals de tot tipus es va iniciar al segle XIX. A partir d’aquest moment apareixen tres camps fonamentals on aprofundir. D’una banda tenim les relacions diplomàtiques i la seva vessant política a partir del segle XX. El desenvolupament de representacions consulars té a veure amb el creixement de l’activitat econòmica amb l’Índia britànica, especialment en el camp del proveïment de primeres matèries (cotó i jute). En aquest sentit, la recuperació de les relacions econòmiques va ser clau per al posterior mutu reconeixement diplomàtic el 1957 quan l’Índia ja era un estat independent. Entre mig queden anys de malvolença degut a la vinculació de Nehru amb el govern republicà durant la Guerra Civil i la posició de l’Índia en el cas d’Espanya a l’ONU. Un altre camp d’interès per a les relacions bilaterals es centra en la missió de Bombay que a partir de 1920 fou administrada per jesuïtes catalans, valencians i aragonesos. Finalment, un seguiment de la premsa i la intel•lectualitat espanyola mostra com l’Índia es va convertir a partir de 1920 en un nou focus d’interès informatiu i pel món acadèmic, com no ho havia estat fins llavors. Aquest descobriment de l’Índia per part de viatgers, artistes i periodistes obra una nova via d’intercanvi que es veurà trucada per la Guerra Civil i el posterior establiment d’un règim que destruí el teixit intel•lectual del país.