Page 100 - Caldera Volcanism Analysis, Modelling and Response
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Pyroclastic Density Currents 75
Figure 8 (a) Sketch of the changes in driving and resisting forces for a PDC that moves over
a change in slope (concave upward curvature); (b) conceptual sketch of an under£ow that
brakes over a change in slope.The elutriated and lofted ¢ne material is su⁄cient to generate
a PDC denser than the atmosphere that propagates further; (c) conceptual sketch of an
under£ow that brakes over a change in slope.The elutriated and lofted ¢ne material is lighter
than the atmosphere and the PDC does not propagate further.
