Tides, earthquakes, and volcanic eruptions

Earth tides result from gravitational pull forces caused by celestial bodies and their motion, of which the Moon and the Sun are the most relevant to our planet. The most striking expression of tides is the sustained ebb-and-flow of the ocean. Tidal forces strongly affect the free masses that compose the fluid envelopes of the Earth and generate ocean and atmospheric tides (see Chapters 4 and 16), but they also affect the solid Earth by generating solid Earth tides. This lunisolar gravitational force is also known for influencing the Earth’s rotation (see Chapter 17), resulting in a mass redistribution that induces a relative reorganization of stresses at the surface of the solid Earth (Lambeck, 2005; Le Moue¨l et al., 2019; Lopes et al., 2021).