  The long-term erosion of steep landscapes is punctuated by dramatic erosional
events that can remove significant amount of sediments within a time-scale
shorter than a seismic cycle. However, the role of such large erosional events
on seismicity is poorly understood. We use QDYN, a quasi-dynamic numerical
model of earthquake cycles to investigate the effect of a large erosional event
on seismicity. The progressive evacuation of landslide sediments is modelled by
a transient normal stress decrease. We show that erosional events with a
shorter duration compared with the duration of a seismic cycle can
significantly increase the seismicity rate, even for small stress changes.
Moreover, large erosional events with a shorter period compared with the
earthquake nucleation time-scale can change earthquake size distribution by
triggering more small events. Those results suggest that large erosional events
can significantly affect seismicity, illustrating in turn the short-term impact
of surface processes on tectonics.
