Rockfall propagation areas can be determined using a simple geometric
rule known as shadow angle or energy line method based on a simple
Coulomb frictional model implemented in the CONEFALL computer program.
Runout zones are estimated from a digital terrain model (DTM) and
a grid file containing the cells representing rockfall potential
source areas. The cells of the DTM that are lowest in altitude and
located within a cone centered on a rockfall source cell belong to
the potential propagation area associated with that grid cell. In
addition, the CONEFALL method allows estimation of mean and maximum
velocities and energies of blocks in the rockfall propagation areas.
Previous studies indicate that the slope angle cone ranges from 27°
to 37° depending on the assumptions made, i.e. slope morphology,
probability of reaching a point, maximum run-out, field observations.
Different solutions based on previous work and an example of an actual
rockfall event are presented here.