creep
The slow, continuous movement of soil, rock, or a fault — imperceptible in the moment but measurable over months or years. Soil creep moves the surface of a hillside downslope under the influence of gravity and water, bending tree trunks, tilting fenceposts, and bulging retaining walls. Fault creep is the gradual, aseismic sliding of a fault — movement without earthquakes, the stress relieved in a slow grind rather than a sudden rupture. Creep is geology's patience, doing in centuries what earthquakes do in seconds.
Etymology
Old English crēopan, to move slowly on hands and knees. The geological sense captures the stealth — the movement is real but hidden in its slowness.
Notes
The Hayward Fault in the San Francisco Bay Area creeps visibly — curbs, sidewalks, and building foundations are slowly offset along the fault trace.
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