Tides are created by the rotation of the Earth and Moon around the common centre of mass. The difference forces between gravitational and centrifugal forces are decisive. These forces ensure that a flood mountain is formed on the Earth both on the side facing the Moon and on the side facing away from the Moon. Therefore, there are ebb and flow twice a day. In addition, the sun also exerts an influence on the tides, which results in spring tides by addition at new and full moon and nipp tides by subtraction at half moon.
The tidal forces can be measured with a gravimeter at any place on earth, independent of the tidal range of the oceans. They are in the range of 0.5 mGal to 1.1 mGal.