Tides, earthquakes, and volcanic eruptions

Abstract

The Earth is a dynamic planet, where earthquakes and volcanoes are among some of its most outstanding expressions. Just like our planet as a whole is subject to lunisolar gravitational tides, seismic and volcanic activity are also influenced by the relative motion of the Sun and Moon. This tidal influence takes different forms, spanning different spatial and temporal scales, from quasiperiodic patterns with semidiurnal to multiannual periods to the triggering of earthquakes and volcanic eruptions. Tidal stresses have been primarily evoked as driving forces, although they are 3–5 orders of magnitude smaller than tectonic stresses, which makes cause-effect relationships elusive. This chapter reviews the different observations of tidal influence in geophysical and geochemical data acquired in tectonic and volcanic settings, as well as the methods that have been developed to detect it. Using case studies, we provide some insights on the sensitivity of geological systems to tidal stresses.