Seeing California move with global positioning satellites



Imperceptible to the human senses, California's tectonic plates deform every day at a rate comparable to the growth of fingernails.

Convection in the mantle under the Earth's solid crust forces continental-size “tectonic plates” to move slowly in different directions. Where plates meet, the motion between them is accommodated by slow deformation, but when the crust is no longer strong enough to withstand the stress buildup, it breaks as an earthquake at weak points we call “faults.”