eötvös

(geophysics) A unit of horizontal gradient of gravitational acceleration, equal to a change in gravitational acceleration of 10^-9 galileo over a horizontal distance of 1 centimeter.

[Etymology: R., Baron von Eötvös; Hungary 1848-1919] geology. Symbol E. Used for expressing horizontal gravitational field gradient, i.e. the change in gravitational acceleration, being defined originally as 10^-9 gal per cm of horizontal traverse, = 10^-9 m·s^-2·m^-1. With gravitational acceleration at sea level ranging from 9.78~ m·s^-2 at the Equator to 9.83~ m·s^-2 at the Poles, over a distance of 10 000 km, the average is about 5 E along a meridian. The variation averages zero along a parallel. Local geological conditions can vary these figures by ±5 E.