Volcanic vent self-similar clustering and crustal thickness in the northern Main Ethiopian Rift.

The spatial distribution of volcanic vents in the northern Ethiopian Rift has been analysed in terms of their self-similar clustering. The fractal distribution of vents has been computed for the monogenetic vents (cones, domes and maar) occurring along the rift valley and in the rift margin. The self-similar clustering of vents has been computed through the analysis of vent centres coordinates by means of the two point correlation method. The vents of the northern Main Ethiopian Rift display a self-similar clustering characterised by a correlation coefficient of 1.41 ± 0.02, with a size range defined by a lower cut-off of 1.1 km and an upper cut-off of 26.5 km. This analysis indicates a probable crustal thickness of 27 km, as indicated by the value of the computed upper cut-off. This value compares well with other estimates for the crustal and lithosphere thickness in the Ethiopian Rift.