Analysis of stress distribution along imbricate surfaces within a sand-box
model of an accretionary wedge is used to calculate the condition for slip
along an active frontal fault and the basal decollement. The same theory is
applied for finding the stress limit that allows formation of a new fault
in front of the sand wedge. When this stress limit is reached, the sole thr
ust propagates rapidly forward along the basal decollement and a new fault
is created. Comparison between theory and experiment shows that stresses wo
uld be underestimated, if compaction of the shortened layer is not accounte
d for in the calculations.