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M. Kousalya ¹, T. Seshunarayana ¹, P. Prabhakara Prasad ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad - 500 007, IN

Abstract

Measurement of vibrations caused by vehicular traffic around Charminar, a monument at Hyderabad, was carried out using three component velocity sensors and high-resolution digital seismograph. These measurements were done at different levels viz., ground, middle, top level and at other accessible levels of the structure. Acceleration and displacement were computed from the velocity-time series. Peak particle velocity was found maximum at the top level in the north-south direction.

Keywords

Environmental Geophysics, Archaeo-Geophysics, Vibration, Velocity, Acceleration, Displacement, Charminar, Andhra Pradesh.

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T. Seshunarayana ¹, P. Senthil Kumar ¹, V. Sampath Rao ¹, D. Mysaih ¹, K. Satish Kumar ¹, P. Pavan Kishore ¹

Affiliations
1 National Geophysical Research Institute, Uppal Road, Hyderabad-500007, IN

Abstract

Delineation of shear zones and fracture systems in hard rock areas is essential in locating potential groundwater zones. The Mu1tichannel Analysis of Surface Waves (MASW) is a new developing seismic geophysical technique, which has now been widely used in imaging shallow subsurface, in terms of shear wave velocity. We test its potentiality in Hyderabad granite terrain, at Wailapally watershed, for delineating shear zones and fractures in a shallow granite basement covered with thin weathering and alluvium cover. Surface wave data were obtained at three sites using 24 channel seismograph, and were used to model the shear wave velocity of the subsurface. The study clearly demarcates the bedrock depths, shear zones or faults, fractures, weathering and soi1 covers in the shallow subsurface up to a depth of -30 m, the results are also in good agreement with the surface geological observations. Therefore, the MASW is an excellent geophysical tool that can clearly demarcate the shallow structures favorable for groundwater in hard rock areas.

Keywords

Surface Waves, Shear Zones, Fractures, Granite, Groundwater, Wallapally, Hyderabad, Andhra Pradesh.

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T. Seshunarayana ¹, P. Prabhakara Prasad ¹, S. V. V. Prasada Rao ¹, K. Subrahmanyam ¹, G. Varadarajan ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad, IN

Abstract

Crosshole seismic survey was conducted to decipher the nature of the exposed rock mass in Hussain Sagar Lake at Hyderabad to erect a monolithic Buddha statue weighing about 470 tonnes. The purspose of the survey was to determine the continuity of subsurface conditions between borehole locations. The technique consists of in situ measurements of travel time of the seismic waves generated by an impulse in one borehole, its reception in the other and computation of seismic velocity. Analysis of the velocity data provided necessary information regarding the soundness of the rock mass.

Keywords

Tomography, Crosshole Seismics, Detectors, P and S waves, Shear wave, Andhra Pradesh.

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T. Seshunarayana ¹, B. Rajendra Prasad ¹, A. S. S. S. R. S. Prasad ¹, D. Mysaiah ¹

Affiliations
1 National Geophysical Research Institute (CSIR), Uppal Road, Hyderabad - 500 007, IN

Abstract

A detailed, integrated gravity and magnetic study across the Main Central Thrust (MCT) along the Pala-Maneri traverse in Uttaranchal, NW Himalaya was carried out. The gravity data was acquired using a CG-3 gravity meter with an accuracy of 0.005 mGal, while magnetic data was acquired using a proton precession magnetometer with a station interval of 20 m. Data was collected along a 11.7 km, NE-SW traverse from Pala to Maneri along the proposed route of a hydroelectric headrace tunnel. The measured variation in the gravity field was approximately 70 mGal, with two prominent highs recorded at distances of 0.5 km, 7.5 km and lows at 3.0 km, 10.5 km from Maneri. The gravity highs can be attributed to presence of high-density rocks along the thrust planes. The sharp gravity low recorded at 10.5 km distance possibly indicates a sympathetic fault of the MCT that is highly saturated with fluids (water). The broad gravity low between 2.5 km and 4.0 km distance is likely to represent the gravity signature of the MCT itself. The measured variation in the magnetic field was approximately 285 nT. The associated gravity and magnetic signatures located several faults along the traverse including presence of the MCT at Kumaltigad.

Keywords

Gravity and Magnetic, Thrust Planes, MCT, Modeling, High-Density Rocks.

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R. Pradeep Kumar ¹, D. Srinagesh ², T. Seshunarayana ², R. K. Chadha ², Narender Bodige ³, G. Suresh ², D. Hima Chandan ¹, C. V. R. Murty ⁴

Affiliations
1 Earthquake Engineering Research Centre, International Institute of Information Technology, Hyderabad 500 032, IN
2 CSIR-National Geophysical Research Institute, Hyderabad 500 007, IN
3 Department of Civil Engineering, Anurag Group of Institutions, Hyderabad 501 301, IN
4 Department of Civil Engineering, Indian Institute of Technology Madras, Chennai 600 036, IN

Abstract

A ground-structure vibration response study was carried out at the Ramappa Temple near Warangal, Telangana, India, shaken by underground blasting undertaken at the neighbouring Devadula Lift Irrigation Project to build water tunnels. The intensities of vibrations were examined – subsurface and ground vibrations were measured using velocity meters, and shaking at the temple using accelerometers. The study concluded that high-frequency vibrations of the ground were filtered by the soft natural clay bed underneath, and vibrations at the temple structure were small and well below the levels that can cause damage to it. Here we present the scientific findings of the vibrations recorded during the blasts and their implications.

Keywords

Heritage Structure, Structural Response, Tunnel Blasting, Vibrations, Vulnerability Assessment.

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