Keeping an ear to the ground

Updated on: Monday, November 07, 2011

How well do we know Mother Earth that gives us “boarding and lodging” and all other facilities for life? “Very little,” will be a fair answer, in spite of its closest proximity and constant contact.

Man has been trying to learn more and more about the Earth, its surface, inside, and surroundings during the past several centuries. The search continues incessantly. Perhaps it will never end. The study is often referred to as geophysics.

The word geophysics challenges precise definition. We may say that it is the physics of the Earth and its environment. It embraces several branches of knowledge, such as atmospheric science, earthquake, geology, geomagnetism, meteorology, oceanography, seismology, tides, volcanology, weather, and winds.

In other words, geophysics is the convergence of geology, physical geography, astronomy, meteorology, and physics in general. Geophysics studies a variety of areas, including the shape of the Earth, its gravitational and magnetic fields, dynamics, internal structure, and composition. It touches the properties of magma, which is a hot liquid inside the earth, volcanoes, rocks, mineral deposits, groundwater, hydrology, and of course, the atmosphere and beyond.

Elements

There are numerous technical terms in geophysics without which we will not be able to make any meaningful discussion on the subject.

Let us have a quick look at some of them. Atmospheric science covers the study of the atmosphere, its processes, and the effects other systems have on the atmosphere. It includes atmospheric electricity that entails electrical discharges. Studies have to be made on ionosphere, terrestrial magnetism, and Van Allen belts — radiation belts comprising highly energetic ionised particles trapped in the Earth's geomagnetic fields.

Seismology includes the study of earthquakes and seismic waves that move through and around the earth. Geodesy is concerned with the determination of the size and shape of the earth, the precise positions of points on its surface, and the description of variations of its gravity field. Meteorology and climatology involve studies of the weather.

Geothermometry is the branch of geology that measures temperatures deep below the surface of the Earth. It deals with the heating of the Earth, heat flow, volcanology, and hot springs.

Hydrology is the area that deals with ground and surface water, its properties, distribution, and effects of water on the Earth's surface and in the soil. It may touch glaciology as well.

Aeronomy is the study of the physical structure and chemistry of the atmosphere. It covers all planetary atmospheres in which physical and chemical processes result from the dissociation and ionisation phenomena.

Geomagnetism is the study of the Earth's magnetic field. Then there is tectonophysics, which is the branch of geophysics dealing with the physical processes involved in forming geological structures.

Geodynamics is the study related to measuring, modelling, and interpreting the configuration and motion of the crust, mantle, and core of the Earth.

Glaciology is the study of glaciers and their effects on the landscape. It deals with the nature, distribution, and action of glaciers and their effects on the Earth's topography. Petrophysics studies the occurrence and behaviour of rocks, soils, and fluids.

NGRI

The premier institution in India that is engaged in serious studies and research in this fascinating discipline is the National Geophysical Research Institute (NGRI), Uppal Road, Hyderabad – 500 606; Web: www.ngri.org.in

The NGRI, a constituent laboratory of the Council of Scientific and Industrial Research, was established in 1961 with the prime objective of research in multidisciplinary areas of earth sciences. The institute plays a pivotal role in extensive research in the diverse branches of geophysics, using the services of highly competent scientists.

The core research areas are:

Exploration

Satellite and land gravity and magnetic (G-M) data for understanding the geodynamics of the lithosphere and the exploration of natural resources.

Mesozoic sediments for hydrocarbon exploration.

Application of magneto-tellurics to natural resources exploration.

Deep resistivity sounding (DRS) and controlled source audio magneto-telluric (CSAMT) studies for upper crustal structure.

Exploration of gas-hydrates along Indian continental margins.

Exploration of hydrocarbons using geochemical tracers.

Structure, tectonics, and subsidence studies of the Bay of Bengal basin with implications of hydrocarbon prospects.

Minerals, engineering

Electrical and electromagnetic field and physical modelling for shallow sub-surface studies.

Petrology and geochemistry of different rocks in central India.

High-resolution multi-parameter airborne geophysical surveys.

2D and 3D seismic studies in various coal basins of India.

Studies on rock properties and rock fracture and in-situ stress measurements in deep boreholes.

Groundwater

Groundwater management in hard rock aquifers. Isotopic and geochemical investigations in the coastal aquifers.

High-resolution geophysical investigations to delineate cavities and vesicular basaltic zones for minerals and groundwater resources.

Sustainable development and management of water resources in different problematic terrain.

Quaternary geo-chronological studies (paleo-seismology, -tsunami, and -climatology and exhumation).

Earthquakes

Application of interferometric synthetic aperture radar (InSAR) to measure ground deformation for seismic hazard studies.

Seismogenic earthquake sources for seismic hazard assessment.

Rigidity and kinematics of the Indian plate and its margins by Space geodesy techniques.

Study of the Indian plate geo-dynamics through intense seismic and GPS campaign mode monitoring.

Lithospheric structure, deformation and tectonics of the eastern Himalayas and the Andaman arc regions.

Study of source processes and crust-mantle structure of seismic zones.

Lithosphere

Thermal and geodynamic evolution of Indian lithosphere and seismogenesis of earthquakes.

Isotopic studies of alkaline intrusions.

Migration of the Indian subcontinent during the Cretaceous (the period after the Jurassic).

Heat flow, heat production, and crustal thermal structure of the Indian shield.

Structural and remote sensing studies in high-grade terrains of southern India.

Study of hydrous minerals at high pressures.

Evolution of the lithospheric mantle and the crust.

Late quaternary paleo-climatic and paleo-oceanographic studies.

Deep structure and evolution of the Indian subcontinent with special reference to cratons.

Modelling

Innovative techniques for modelling of geophysical data.

.Numerical simulations of convection in the Earth's deep interior.

Geo-environmental studies

Ecology and environmental studies in and around greater Hyderabad.

Environmental impact assessment and remediation of inorganic and organic pollutants derived from mining and industrial activities.

Environmental geophysics: conservation of soil and groundwater in dry land agricultural environment.

Keeping an ear to the ground

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