Volcanoes in rift situations often show distinctive “hour-glass” fault patterns, with increased
fault throw as the volcano is approached. We present analogue models that show that this is
caused by an interaction of the regional stress field with that set up by the volcano mass. For
faults to be reorientated there must be a ductile layer below the volcano. This can be hot
crust at mid-ocean ridges, continental rifts, or weak sedimentary strata. Increased volcano
size or mass and lower brittle/ductile ratios lead to increased fault curvature, whereas an …

The effect of volcanic constructs on rift fault patterns … Volcanoes in rift situations often
show distinctive hour-glass fault patterns, with increased fault throw as the volcano is
approached. Analogue models are presented that show that this is caused by an interaction
of the regional stress field with that set up by the volcano mass. …