Fig. 11

The influence of grain size on the correlation between vesicularity and grain shape. Vesicularity values here represent vesicularities per pyroclast measured by pycnometry as in Fig. 4A-D. The color scale shows the general degree of shape regularity, calculated by adding up normalized values of elongation, sphericity, Krumbein roundness and compactness and normalizing the results between 0 and 1. A Vesicularity plotted against most dominant modal grain size of individually crushed pyroclasts. Each data point represents one crushed pyroclast sample, as in Fig. 4A-D. The most dominant modal grain size in each of these pyroclasts is calculated from dynamic image analysis data using Blott and Pye (2001). B Vesicularity plotted against grain size bin. Each data point (stripe) represents a subset of grains of one crushed pyroclast sample that fall in a certain grain size bin. Hence, every data point in (A) corresponds to multiple data in (B), representing one specific pyroclast