(a) and (d) Exemplary starting and (c) and (f) final models of two (out of 200) arbitrary Markov chains with the evolutions of the model dimension (b) (number of Voronoi cells (Dim) and (e) RMS-misfit. The initial models in (a) and (d) consist of 12 and 11 cells, respectively. Cell centres are indicated by white dots. The final models after 10 000 iterations (c) and (f) consist of 46 and 50 cells, respectively. Black and red dots indicate receiver and source point positions in the models, respectively. (b) and (e) The evolutions of model dimensions and RMS-misfit are shown for all 200 single chains. Bright colours indicate high concentrations of dimension or RMS values at certain iteration steps.