True Polar Wander Theory (as posted on The Extinction Protocol today) suggests that if the shape/weight of the Earth’s crust is increased (for example by a super sized volcano) formed far from the Earth’s equator then that would create an imbalance, which if great enough would cause the planet to tilt to regain balance resulting in true polar wander.
Scientists' consider that in many ways this theory overlaps with current plate tectonic understandings.
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Earth Undergoing True Polar Wander
http://earthsky.org/earth/earth-is-undergoing-true-polar-wander-sci...