Strain Rates and Recurrence Intervals

Scientists can estimate earthquake recurrence intervals for a given fault if they know the rates of strain buildup and how much strain is released during a typical earthquake at that location.  For example, if plate motions are building strain along a given fault at a rate of 1 inch per year, the fault will accumulate 100 inches of strain in 100 years.  If each earthquake on that fault caused 200 inches of displacement (slippage), then one quake can be expected every 200 years.

Recurrence Interval  =  (Displacement During a Typical Earthquake) / (Rate of Strain Buildup)

200 years  =  (200 inches of displacement) / (1 inch strain buildup per year)