Microgals

Microgals are a unit of acceleration used in gravity measurements. A Gal equals 1 centimeter per second squared, so a microgal is 10^-6 Gal or 10^-8 meters per second squared. The microgal is used to express very small variations in Earth's gravitational field in geophysics, geodesy, and metrology.

In practice, gravity signals are often described in microgals because natural and anthropogenic processes induce changes at this scale. Microgal precision is important for monitoring tides, groundwater changes, crustal deformation, volcanic activity, and mineral exploration through gravimetric surveys.

Instrumentation and methods: Absolute gravimeters measure g by observing the free fall of a test mass, while relative gravimeters compare gravity against a stable reference; among the most sensitive instruments are superconducting gravimeters and quartz-flexure devices. Modern systems can approach microgal-level resolution in practice, with long-term stability improving through continuous monitoring. Data processing applies corrections for ocean loading, atmospheric pressure, tides, instrument drift, and environmental effects.

Notes: The Gal and its subunits are named after Galileo Galilei. The microgal is a standard unit in geophysics for expressing tiny gravity variations; typical gravity values are about 9.8 m/s^2, i.e., about 980,000,000 μGal.