geotechinical engineering & Geographic Information Sysytem

Magnetic and Gravity Methods

Magnetic geophysical surveys measure small, localized variations in Earth’s magnetic field. The magnetic properties of naturally occurring materials such as basic igneous rocks allow and magnetic ore bodies them to be identified and mapped by magnetic surveys. Anomalies or Strong local magnetic fields are also produced by buried steel objects. Magnetometer surveys find underground storage drums, tanks, piles and reinforced concrete foundations by detecting magnetic anomalies they produce. The goal of studying detailed gravity data is to provide a better understanding of subsurface geology. The gravity method is a relatively on-invasive, cheap, on-destructive remote sensing method. It's also passive that is, no energy need be put into ground in order to acquire data, and thus, method is well suited to a populated setting. The small portable instrument used also permits walking traverses. Measurements of the gravity provide information about densities of rocks underground. There is a wide range in density among rock types, so geologists can make inferences about distribution of strata. The gravity method involves measuring gravitational attraction exerted by earth at a measurement station on the surface