Analogue benchmarks of shortening and extension experiments

We report a direct comparison of scaled analogue experiments to test the reproducibility of model results among ten different experimental modelling laboratories. We present results for two experiments: a brittle thrust wedge experiment and a brittle-Viscous extension experiment. The experimental set-up, the model construction technique, the viscous material and the base and wall properties were prescribed. However, each laboratory used its own frictional analogue material and experimental apparatus. Comparison of results for the shortening experiment highlights large differences in model evolution that may have resulted from (1) differences in boundary conditions (indenter or basal-pull models), (2) differences in model widths, (3) location of observation (for example, sidewall versus centre of model), (4) material properties. (5) base and sidewall frictional properties, and (6) differences in set-up technique of individual experimenters.