• K B Chary

      Articles written in Journal of Earth System Science

    • In situ stress measurements using hydraulic fracturing method

      T N Gowd S V Srirama Rao K B Chary F Rummel

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      The firstin situ stress measurements in India were carried out in 176 m deep borehole by employing deep-hole wireline hydraulic fracturing equipment. The results reveal that the direction of maximum compression is oriented at N 35° E, and the existence of high-near-surface horizontal stresses compared with the overburden pressure. This can be attributed to the continuing convergence of Indian and Eurasian plates. Earthquakes experienced near Hyderabad could be due to refracturing of some NNE or NE trending mineralized fractures which persistently occur in the area, as these fractures are critically oriented with respect to the present-day stress field.

    • Tectonic stress field in the epicentral zone of the Latur earthquake of 1993

      S V Srirama Rao K B Chary T N Gowd F Rummel

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      In situ stress measurements by hydraulic fracturing were carried out in the 617 m deep borehole specially drilled in the epicentral zone of the 1993 Latur earthquake for the purpose of research. The stress measurements carried out at 592 m depth in this borehole are the deepest of all such measurements made so far in the Indian shield. The maximum and minimum principal horizontal stresses (SH max andSh min) have been derived from the hydrofracture data using the classical method. TheSH max andSh min are found to be 16.5 and 9.6 MPa at 373 m depth, and 25.0 and 14.1 MPa at 592 m depth, indicating that the vertical gradients ofShmax andShmin in the epicentral zone are 39 MPa/km and 21 MPa/km respectively. The principal horizontal stresses in the epicentral zone are comparable with those at Hyderabad and 30% higher than in most other comparable intra-continental regions. Analysis of the results indicate that the stresses in the focal region of the 1993 Latur earthquake have not undergone any significant change following its occurrence and this is in agreement with a similar inference drawn from the seismic data analysis. It appears that the Latur earthquake was caused due to rupturing of the overpressured fault segment at the base of the seismogenic zone.

    • Elastic properties of granulite facies rocks of Mahabalipuram, Tamil Nadu, India

      M V M S Rao K J Prasanna Lakshmi L P Sarma K B Chary

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      Compressional and shear wave velocities and attenuation measurements have been carried out in some of the borehole samples of acidic, basic and intermediate granulites of Mahabalipuram, Tamil Nadu, India. The results have been obtained at ambient conditions using ‘time-of-flight’ pulse transmission technique at 1.0 MHz frequency. The results show linear relationships between velocity and density, and velocity and attenuation properties of the rocks. The acidic granulites show lower velocities and higher attenuation than the intermediate and basic granulites. The average values of the Poisson’s ratio of acidic, intermediate and basic granulites have been found to be 0.210, 0.241 and 0.279 respectively. The variations in velocities and attenuation in these low porosity crystalline rocks are found to be strongly influenced by their mineral composition. The laboratory velocity data (extrapolated to high pressure) of the present study and the published field velocity data from deep seismic sounding studies indicate that these granulite facies rocks may belong to mid-crustal depths only.

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