Which of the following is a property typically measured by gravity surveying?

Which of the following is a property typically measured by gravity surveying?

• A. Density
• B. Porosity
• C. Permeability
• D. Magnetic susceptibility

Answer: (A)

Gravity surveying detects variations in the Earth’s gravitational field caused by differences in rock density below the surface. Denser bodies pull a gravity instrument a bit more, producing a positive anomaly, while less dense materials create a negative one. By applying corrections (like free-air and Bouguer corrections) and modeling these anomalies, you map how density changes with depth. Porosity, permeability, and magnetic susceptibility are not directly measured by gravity methods: porosity relates to pore space and can influence density but isn’t the primary gravity signal; permeability concerns fluid flow; and magnetic susceptibility is a magnetic property assessed by magnetic methods. The gravity method’s primary measurable property is density, making density the best answer.

Gravity surveying detects variations in the Earth’s gravitational field caused by differences in rock density below the surface. Denser bodies pull a gravity instrument a bit more, producing a positive anomaly, while less dense materials create a negative one. By applying corrections (like free-air and Bouguer corrections) and modeling these anomalies, you map how density changes with depth. Porosity, permeability, and magnetic susceptibility are not directly measured by gravity methods: porosity relates to pore space and can influence density but isn’t the primary gravity signal; permeability concerns fluid flow; and magnetic susceptibility is a magnetic property assessed by magnetic methods. The gravity method’s primary measurable property is density, making density the best answer.