Simple Fault

The geometry of a Simple Fault, the most common fault type used in OpenSHA, is described by the fault's Trace, Average Dip and Upper and Lower Seismogenic Depths. This is the minimum information required to define surfaces on which slip associated with earthquakes occurs.

Simple Faults may be gridded according to different algorithms (e.g. see the Frankel and Stirling Fault Surface definitions).

Fault Trace

A line marking the intersection of a fault (rupture) surface with the surface of the earth. In OpenSHA a Fault Trace is represented with a list of locations (latitude, longitude, depth).

Average Dip

The average dip (angle between the earth's surface and fault plane) along the length of the fault.

Lower Seismogenic Depth

The depth (in km) of the lower limit of seismogenic rupture. This depth is generally based on the maximum depths of microsesmicity in a given region.

Upper Seismogenic Depth

The depth (in km) of the upper limit of seismogenic rupture. This depth is generally applied regionally to reduce near surface seismic energy (moment) release in hazard models (to match observations).