Morphometry and evolution of arc volcanoes

GROSSE, PABLO; VAN WYK DE VRIES, BENJAMIN; PETRINOVIK, IVAN; EUILLADES, PABLO; ALVARADO, GUILLERMO

GEOLOGY

Geological Society of America

Año: 2009 vol. 37 p. 651 - 654

0091-7613

Volcanoes change shape as they grow through eruption, intrusion, erosion, and deformation.To study volcano shape evolution we apply a comprehensive morphometric analysis totwo contrasting arcs, Central America and the southern Central Andes. Using Shuttle RadarTopography Mission (SRTM) digital elevation models, we compute and defi ne parameters forplan (ellipticity, irregularity) and profi le (height/width, summit/basal width, slope) shape, aswell as size (height, width, volume). We classify volcanoes as cones, sub-cones, and massifs,and recognize several evolutionary trends. Many cones grow to a critical height (~1200 m)and volume (~10 km3), after which most widen into sub-cones or massifs, but some grow intolarge cones. Large cones undergo sector collapse and/or gravitational spreading, without significant morphometry change. Other smaller cones evolve by vent migration to elliptical subconesand massifs before reaching the critical height. The evolutionary trends can be related tomagma fl ux, edifi ce strength, structure, and tectonics. In particular, trends may be controlledby two balancing factors: magma pressure versus lithostatic pressure, and conduit resistanceversus edifi ce resistance. Morphometric analysis allows for the long-term state of individualor volcano groups to be assessed. Morphological trends can be integrated with geological,geophysical, and geochemical data to better defi ne volcano evolution models.