Gravity Surveys

Applications Include

Fault problems

Ground water inventories

Intrusion delineation

Basin studies

State–of–the–art gravity meters can sense differences in the acceleration (pull) of gravity to one part in one billion. Measurements taken at the Earth’s surface express the acceleration of gravity of the total mass of the Earth but because of their high sensitivity the instruments can detect mass variations in the crustal geology. For example a high angle, basin and range type fault will have older consolidated rocks on one side and relatively unconsolidated valley fill sediments on the other side of the fault. Mass is volume x density, and there is a density contrast in the order of 0.5 gm/cc across the basin and range fault, therefore the gravity field will express the position of the fault, in the high gradient zone, between the mountain and the valley. The amplitude of the variation from the high to the low of the gravity gradient zone is a function of the displacement on the fault. In addition to providing insights to fault problems, gravity methodology applies to any geologic problem involving mass variations.