Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

V. Cermak ¹, J. Kubik ¹, M. M. Saikia ², M. V. D. Sitaram ²

Affiliations
1 Geophys. Inst., Czechosl. Acad. Sci, 141-31 Praha, Czechoslovakia, GB
2 Geoscience Div., Regional Research Laboratory, Jorhat, IN

Abstract

The empirical relationship between observed P_n (Sub-Moho) seismic velocities and the surface heat flow (including also the assessed crust-upper mantle temperatures) was used to improve the understanding of the regional geothermal activity of the North-Eastern Region of India. Vertical seismic velocity profile was further converted into radiogenic heat production and the knowledge of the crustal heat sources helped in both, to estimate deep temperature distribution within the crust and to evaluate the Moho heat flow. The most probable existing temperature at the crust-upper mantle boundary is between 800 and 900°C and the flow of heat from below the crust attains about 50% of observed surface heat flow, i.e, about 30mW. m^-2.

Keywords

North-East Region Heat Flow, Geothermal Model Seismology, Meghalaya, Assam, Nagaland, Arunachal Pradesh.

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V. Cermak ¹, L. Bodri ², M. M. Saikia ³

Affiliations
1 Geophys. lnst., Czechosl. Acad. Sci., Praha, 141-31 Czechoslovakia, SK
2 Geophys. Res. Group, L. Eotvos Univ., Budapest, 1083, HU
3 Geoscience Division, Regional Research Laboratory, Jorhat, 785 006, IN

Abstract

The study area, which represents a boundary collision zone between the Indian and Euroasian plates, has been the focus of intense seismic studies for decades. Except for events that have been clearly associated with the underthrusting of the Indian plate. the data reported by the regional network in the Northeastern Regions of India indicate a layer of concentrated seismicity in the lower crust at a depth range of 30 to 40 km. The lithosphere rheology was assessed on the basis of the frictional failure in the brittle regime, and power-law steady-state creep in the ductile regime. Rheological profiles were constructed fora 1-0 crustal structural and thermal model. The rheological stratification of the lithosphere was compared with the earthquake depth distribution which indicated a reasonable confinement of seismicity to brittle horizons.

Keywords

Earthquake, Arakan-Yoma Fold Belt, Northeastern India.

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