gravimetria

Gravimetria, or gravimetry, is the measurement of the Earth's gravity field through local measurements of the acceleration due to gravity (g). Variations in g reflect changes in mass distribution and topography, making gravity data useful for geodesy and geophysics. Observations can be static, giving a single value, or time-varying, tracking processes such as groundwater movement or tectonic deformation.

Principles: absolute gravimetry determines g directly by observing a free-falling test mass or using laser interferometry. Relative gravimetry compares g at a site with a reference instrument, using sensors such as spring gravimeters, corner-cube devices, or superconducting gravimeters. Relative methods are common for surveys, while absolute methods provide high accuracy for calibration and gravity base networks.

Corrections and processing: measured gravity values require corrections for tides, atmospheric pressure, ocean loading, land movement, and instrument drift. Data are converted to gravity anomalies or Bouguer/Free-Air values to infer subsurface density, crustal structure, or water storage.

Applications: gravimetry supports geodesy, tectonics, mineral and groundwater exploration, volcanology, oceanography, and calibration of satellite gravity field models. It provides high-resolution, localized gravity information and complements seismic and magnetic data.

History: gravimetry has roots in pendulum and free-fall experiments, culminating in modern absolute and superconducting instruments. The development of gravimetric networks and reference frames contributed to precise maps of the geoid and Earth's mass distribution.