Local Correlations Between Lava Flow Width Behavior and Underlying Slope
M. N. Peitersen, D. A. Crown, A. Snyder Hale (University of Pittsburgh)
A lava flow's width behavior is indicative of its response to topography, emplacement regime, and physical properties. Previous studies have shown unexpectedly poor correlations between flow widths and underlying slopes. Flow behavior has been characterized by analysis of individual features (local maxima and minima) on plots of slope and width as functions of distance. Initial analysis was done by visual inspection. For ten Episode 1-5 Puu Oo flows (Kilauea Volcano), the following correlations are evident: 1) width peaks align with slope troughs, and 2) width troughs align with slope peaks. Such inverse (negative) correlations between width and underlying slope imply topographic control on flow emplacement. However, features cannot always be clearly correlated. Major changes in width also occur where slope is relatively constant, suggesting that some factor besides topography is involved. Where correlations exist, some are positive (reversed) or slightly offset. Magnitudes of correlated features can differ significantly; minor changes in slope occur with major changes in width, and major slope changes sometimes have little or no effect on width behavior.
An automated feature recognition procedure has been developed and applied to Puu Oo flows. Results for flows 2.1 and 4.1 are shown in Table 1. The automatic method is more precise and hence shows fewer positional correlations.
Table 1: Results of Automatic Detection/Correlation of Lava Flow Features.