4D MORPHOMETRY OF TRANSIENT TUMULI IN BASALTIC LAVA FLOW EXPERIMENTS

Lava flow tumuli are protuberant structures that form in response to high magmatic pressure caused by lateral changes in flow pathways or by flow into topographic depressions. Thus, the distribution of tumuli across a flow field can provide insight into subcrustal flow channels and pre-existing topography. In this study, we attempt to generate tumuli with large-scale (decimeter-to-meter) experimental lava flows over small cylindrical depressions. Using active-flow 4D morphometry, we find that topographic depressions do provide an environment for pressure-driven topographic uplift. However, in volume-limited flow experiments, this effect is transient, and the pressure features are not preserved in the finite topography. This may have implications for interpreting the morphology of active lava channels, which have a dynamic morphometric pattern that is not preserved after solidification. Identifying and mapping transient pressure features in active channels could provide insight into subsurface topography and furthermore, illuminate the effects of thermal erosion.