Geoid Height Calculator
The Geoid Height Calculator returns the geoid height at the latitude and longitude specified by the user. The geoid is one approximation of Earth's shape due to gravity, roughly coinciding with mean sea level. Because the inside of our planet is non-uniform, gravity is not constant at the surface. If Earth were completely covered in an ocean, the water would swell over gravity highs (where there is more mass below the surface) and depress in areas of gravity lows (where there is less mass below the surface). The geoid approximates this hypothetical ocean surface, representing a geopotential surface. To think of it another way, if we were able to walk on the geoid, we would experience a constant value of gravity.

Plate Motion Calculator
The Plate Motion Calculator calculates tectonic plate motion at any location on Earth using one or more plate motion models.