Eotvos (unit)
The Eotvos (symbol: E, sometimes EU) is a unit of measure of the gravity gradient. It is named after the Hungarian physicist Baron Loránd Eötvös.
One Eotvos is defined as 10-9 s-2. In SI base units, this is equivalent to 10-9 /s2. This is often expressed as 10-9 Gal/cm, where Gal is the unit of gravitational acceleration.
The Eotvos unit is primarily used in the fields of gravity surveying, geophysics, and geodesy to quantify small variations in the gravitational field. These variations are often caused by subsurface density differences, making the Eotvos a useful tool for mineral exploration, oil and gas exploration, and mapping subsurface geological structures.
The gravity gradient measured in Eotvos represents the change in the gravitational acceleration vector per unit distance. Modern gravity gradiometers, often airborne, can measure gravity gradients with a precision of fractions of an Eotvos.
The Eotvos number (Eo), a dimensionless number used in fluid mechanics, is sometimes confused with the Eotvos unit. They are distinct concepts.