Geophysical methods are techniques used to study the physical properties of the Earth and its surroundings. There are several types of geophysical methods that are commonly used in geophysics, including:
Seismic methods: Seismic methods involve the use of sound waves to image the subsurface of the Earth. Seismic waves can be generated artificially by detonating explosives or by using a vibrating source, such as a seismic truck or a hammer. The waves are then detected by sensors called geophones, which are placed on the ground. Seismic methods are used to study the structure and properties of the Earth’s interior, including the location and characteristics of oil and gas reservoirs, the depth and structure of faults and other geological structures, and the properties of the Earth’s mantle and core.
Electrical and electromagnetic methods: Electrical and electromagnetic methods involve the measurement of the electrical properties of rocks and soils. Electrical conductivity can be used to map the distribution of minerals and fluids in the subsurface, while electromagnetic methods can be used to detect conductive bodies, such as mineral deposits or underground water reservoirs. These methods are commonly used in mineral exploration and environmental studies.
Gravity and magnetic methods: Gravity and magnetic methods involve the measurement of the Earth’s gravitational and magnetic fields. These methods can be used to study the distribution of mass and magnetic minerals in the Earth’s crust and to detect buried structures, such as faults, dikes, and mineral deposits.
Remote sensing: Remote sensing involves the use of satellite imagery and other types of remote sensing data to study the Earth’s surface and atmosphere. Remote sensing can be used to study changes in the Earth’s land cover, vegetation, and climate, as well as to monitor natural hazards, such as earthquakes, volcanoes, and landslides.
Ground Penetrating Radar: (GPR) is a geophysical method that uses high-frequency electromagnetic waves to image the subsurface of the Earth. It is a non-invasive technique that can provide information on the internal structure of the ground without the need for excavation.
Time-domain electromagnetic: (TDEM) is a geophysical method that uses electromagnetic fields to image the subsurface of the Earth. TDEM is based on the principles of electromagnetic induction, which involves the generation of a primary magnetic field that induces a secondary electric field in the subsurface. The secondary electric field is then measured and analyzed to provide information on the electrical properties of the subsurface.
Borehole geophysics: Borehole geophysics refers to the use of geophysical methods to study the subsurface properties and structures of boreholes or wells. Borehole geophysics is a valuable technique in geological, hydrological, and geotechnical studies.
These geophysical methods are often used in combination with each other to obtain a more complete picture of the Earth’s subsurface and surroundings.