Fig. 1: Block-and-ash flow deposits at Merapi volcano.
From: The fragmentation-induced fluidisation of pyroclastic density currents
a Outcrop of the block-and-ash flow deposit from the June 14, 2006, event at Merapi volcano at 2.8 km from source. Each yellow bar is 1 m long. b Proximal, medial and distal grain-size distributions of samples collected at Merapi for all three BAFs of June 14, 2006 (blue), October 26, 2010 (grey) and November 5, 2010 (red) (Φ = −log2(d[mm]). Note that samples in the “proximal” region were collected close to the proximal/media transition. c Sorting and mean grain-size parameters for all samples plotted with distance. The runout of each event is indicated on the top with vertical arrows. d Number of particles with diameter >d as a function of particle size for all samples of the three BAF events at Merapi. The two black reference dashed lines illustrate the difference in slope between power-law distributions with fractal dimension of 2.9 and 3.446, which are typical bounds of the slope measured in other PDC deposit samples around the world. The power-law exponent D is plotted against distance for all samples. The greyed box represents the range of D exponents measured in other PDC deposits.
