Towards a comprehensive morphometric classification of composite volcanoes

GROSSE, P.; KERVYN, M.; VAN WYK DE VRIES, B.

Paris

Congreso; 8th IAG International Conference on Geomorphology; 2013

International Association of Geomorphologists

Shape and size are fundamental properties of a volcano. This is reflected in the fact that most volcano classifications are based entirely or partially on morphology. However, most existing classifications are qualitative and unsystematic, based on vague morphological characteristics and sometimes also using other data (e.g. composition). This has led to classification schemes that are ambiguous or inconsistent, containing different and in some cases overlapping terminology such as simple, composite, compound, complex, cluster, multiple, twin, shield, shield-like, somma, collapse-scarred, etc. In order to obtain a comprehensive classification, quantitative and comparable morphometric data for all volcanoes at a global scale should be analyzed. To this end, we have used the near-global SRTM DEM to compile a database of morphometric parameters of approximately 800 composite volcanoes that are listed in the Smithsonian Institution Global Volcanism Program database. The parameters were obtained using a specifically developed code (MORVOLC) which computes several parameters that thoroughly and quantitatively describe the morphology of volcano edifices. Analysis of the database indicates that edifice shape can be reasonably summarized by a number of independent parameters: height / basal width ratio, summit width / basal width ratio, ellipticity index (ei), irregularity index (ii), average slope, number of main vents and presence of large summit crater or caldera. More detailed characterization can be obtained considering the variation with height of ei, ii and slope. Edifice size can be summarized with height, basal width and volume. Statistical cluster analysis of these parameters via different algorithms results in a set of possible classification schemes. The usefulness and validity of the obtained categorizations are discussed in terms of their links with the dominant constructive and destructive processes controlling edifice morphologies.