Slip rate

The rate of motion obtained when the amount of offset is divided by a time interval. The common units of measure are millimeters per year or meters per thousand years (mm/yr or m/k.y.; equivalent units). The average slip rate at a point along a fault is commonly determined from geodetic measurements, displacement of manmade features, or from offset geologic features whose age can be estimated or measured. Offset is measured parallel to the predominant slip direction or estimated from the vertical or horizontal separation of geologic features. In special cases, interval slip rates may be calculated if the times and amounts of slip of prehistoric earthquake events have been determined. This type of high-quality data is rather sparse.