The Relation of Axial and Orbital Precessions to Volcanic Activity

Precession on a gyroscope.

The Earth undergoes large climate cycles that correspond with cycles in its axial and orbital precessions that affect the Earth's tilt toward the Sun, which in turn effects the possible severities of the planet's seasons. The combined effect of these precessions creates climactic cycles that manifest as growing or shrinking ice sheets. Growing ice sheets, especially as seen in ice ages, push down on the Earth's crust, trapping pressure that is released when the ice lets up and the crust is allowed to swell again. This swelling has been found to correlate strongly with volcanic activity in volcanically-prone areas of the Earth's crust.

As Scott K. Johnson writes for Ars Technica on 11 December 2012, "If the pressure pushing down on a magma chamber decreases as the crust rebounds upwards, it becomes easier for the magma to work its way to the surface, leading to an eruption. In this way, large climate changes could act to loosen the corks keeping eruptions bottled in, so to speak."

Evidence for this geological phenomenon has been found in a study published by Steffen Kutterolf, Marion Jegen, Jerry X. Mitrovica, Tom Kwasnitschka, Armin Freundt and Peter J. Huybers of the Geological Society of America on 4 September 2012.