Shell lab sandbox experiment (~1980) with simultaneous conjugate crossing faults (left, going down) and result unfaulted by ezValidator (right, going up). Data from Nieuwland, D.A. & M. Nijman (2001): The atlas of structural geometry: a digital collection of 25 years of analogue modelling. Netherlands Journal of Geosciences 80 (2): 59-60 (CD).
The experiment shows that both faults are active at the same time. The unfaulting shows an overlap at the point where the two faults intersect. In the experiment, sand seems to ‘disappear’ from this intersection.