Vent distribution and sub-volcanic systems: Myths, fallacies, and some plausible facts

Abstract

Characterization of spatially distributed volcanism includes analysis of vent alignments, zones of high probability density and cluster membership assignment. Attempts to identify patterns from the spatial distribution of vents have resorted to various methods with the underlying assumption that results from any of those methods should provide quantitative evidence concerning the structure of the array. In contrast, the physical conditions leading to the creation of specific patterns of distribution have received less attention. In this work, the basis for some of the common expectations of studies of vent distribution, and how those expectations match the individual method-inherent assumptions, are reviewed. Throughout this work it is shown that the spatial distribution of volcanic vents allows us to extract much information concerning the physical structure of the sub-volcanic system. Nevertheless, attention must be given to the fact that not all systems are equal, and therefore, that it is a myth that any quantitative method can provide reliable information. Furthermore, it is shown that some methods even might yield false clues leading to the statistical validation of structures that have no physical support. Thus, in this paper it is highlighted that the selection of methods that fulfill the physical constraints likely to exist on the case of interest is extremely important to promote identification of the most plausible configurations in a robust form. Failure to acknowledge the importance of method selection can be detrimental for the correct understanding of the physical mechanisms underlying volcanic activity, and therefore such practices need to be avoided.