mGal
milligal
Accelerationexact by definition
The milligal is 10⁻⁵ m/s², a thousandth of a gal, and roughly one part per million of Earth's gravity. It is the working unit of gravity surveying: a buried void, a salt dome or an ore body shows up as an anomaly of a fraction of a milligal to a few milligals in a corrected survey.
Watch out: Raw gravity readings have to be corrected before an anomaly means anything. Gravity falls about 0.3086 mGal per metre of elevation (the free-air gradient), varies with latitude by roughly 0.8 mGal per kilometre north-south at mid-latitudes, and shifts with tides by up to 0.3 mGal, so an uncorrected difference of a milligal is more likely to be geometry than geology.
| 1 mGal | 0.00001 m/s² |
Solvers that use acceleration