Planetary EcologistDispersal index (Volcanology 🌋)
Dispersal index is a parameter in volcanology. The dispersal index D {\displaystyle D} was defined by George P. L. Walker in 1973 as the surface area covered by an ash or tephra fall, where the thickness is equal or more than 1/100 of the thickness of the fall at the vent. An eruption with a low dispersal index leaves most of its products close to the vent, forming a cone; an ...