Geophysical instruments are specialized tools used to measure various physical properties of the Earth, such as its magnetic field, gravitational field, electrical conductivity, and seismic activity. These instruments are crucial in the fields of geophysics, geology, and environmental science for understanding the Earth's structure, composition, and dynamics. Here is a brief description of some common geophysical measurement instruments:

1. Magnetometers: These instruments measure the strength and direction of the Earth's magnetic field. They are used in various applications, including mineral exploration, archaeological surveys, and monitoring changes in the Earth's magnetic field.

2. Gravimeters: Gravimeters measure the acceleration due to gravity at a specific location, which can be used to infer subsurface density variations, helping in the exploration for oil, gas, and mineral deposits.

3. Seismometers: These instruments detect and record seismic waves caused by earthquakes, volcanic activity, or人为 explosions. They are essential for studying Earth's crustal movements and understanding seismic hazards.

4. Electromagnetic (EM) instruments: EM instruments measure the electrical conductivity and magnetic properties of the subsurface. They are used in mineral and groundwater exploration, as well as in environmental studies to detect contaminant plumes.

5. Ground Penetrating Radar (GPR): GPR systems use radar pulses to image the subsurface. They are particularly useful for detecting buried objects, such as pipes, cables, and archaeological features.

6. Borehole Instruments: These are instruments that are lowered into a borehole to measure properties at depth, such as temperature, pressure, and rock properties. They are used in oil and gas exploration, as well as in geothermal and environmental studies.

7. Tiltmeters: Tiltmeters measure the tilt or strain of the Earth's surface, which can be indicative of volcanic activity or the movement of the Earth's crust.

8. Inclinometers: These instruments measure the angle of slope or tilt of a borehole, which is important for directional drilling and ensuring that a borehole is drilled along a specific trajectory.

9. Acoustic Well Log Instruments: These are used to measure the acoustic properties of the rock formations surrounding a borehole, providing information about the rock's porosity and permeability.

10. Magnetic Susceptibility Meters: These instruments measure the magnetic susceptibility of rocks and soils, which can provide information about the presence of magnetic minerals and the history of the magnetic field.

These instruments are often used in combination to provide a more comprehensive understanding of the Earth's physical properties and to solve complex geological and environmental problems.