A modified basal outlining algorithm for identifying topographic highs in gridded elevation data, part 2: Application to Springerville Volcanic Field

Abstract

Delineating boundaries of volcanic edifices from surrounding topography is often difficult, time-consuming and subjective. For large volcanic fields, with hundreds of volcanoes, developing methods to efficiently and consistently identify and isolate volcanoes from surrounding topography is of utmost importance. Advances in technology for collecting and processing digital elevation datasets have significantly improved the spatial coverage and accuracy of digital elevation models. This study evaluates the efficacy of two automated methods, a simple closed-contouring algorithm and the newly developed extension of this method, known as the Modified Basal Outlining Algorithm (MBOA), to identify and isolate volcanic cones within the Springerville Volcanic Field in southeastern Arizona. Results from the automated methods are compared to geologically mapped cone boundaries isolated using petrographic and topographic characteristics (Condit, C., 2010. Geosphere 6, 430–443, doi:10.1130/GES00531.1). The MBOA reproduces the maximum height, area and volume for the Springerville Volcanic Field to within a few percent of the values obtained by field mapping; whereas the closed-contour algorithm systematically underestimates the size of the volcanic edifices. Cone steepness, which is often considered to reflect the integrated history of eruptive and erosional processes shaping an edifice, is found to be insensitive to method used to delineate the cone boundary. For all three methods, a negative exponential model can be used to describe the resulting height–frequency distribution of cones, with small differences in the estimated scaling parameters. Results from this study show the MBOA is an effective automated method for identifying and isolating volcanic edifices within a large volcanic field and an improvement over closed-contour algorithms.