Fault Distance

The fault distance (R_F) is one of the measures of the source-site distance currently used in the engineering and seismology applications. It is defined as the minimum distance between the observation point and the earthquake fault.

Different source-to-site distances are commonly used, such as:

Hypocentral distance (M1): distance from the earthquake hypocenter;

Epicentral distance (M2) = distance from the earthquake epicenter;

Distance from the most energetic zone (M3) = distance from the zone of maximum energy release;

Distance from the seismic source or distance from the fault (M4) = minimum distance between the site and the earthquake fault;

Distance from the surface projection of the fault (Joyner-Boore distance) = minimum distance between the site and the fault projection on the ground surface (M5).