DISTINGUISHING LAVA FLOW TEXTURES BASED ON QUANTITATIVE MEASURES OF ROUGHNESS

Mapping lava flow textures and interpreting their emplacement conditions is crucial to understanding the eruptive history of basaltic volcanoes. While textural classifications like a’a and pahoehoe are clear, there are many intermediate textures along the spectrum that are much more challenging to classify objectively. This creates potential confusion, as these names are based on qualitative descriptions of the surfaces that are challenging to standardize between observers. Objective classification of lava flows based on roughness measurements at various scales will allow rapid and consistent mapping of planetary bodies in addition to classification of intermediate terrestrial flows. The diversity of lava flow textures is the result of differing compositions and dynamics within the flow. This study investigates the horizontal scales at which surface roughness calculations can differentiate flow types, suggesting data resolution limits to be considered in planetary lava flow identification. Unmanned Aerial Vehicles (UAVs) were used to collect aerial imagery at the Craters of the Moon lava field in Idaho. This high-resolution imagery was used to create Digital Terrain Models (DTMs) that were down-sampled to simulate a range of lower resolution imagery for comparison. Results show that roughness can be used to distinguish lava flow textures. The data resolution necessary to differentiate lava flow textures is determined by how precise the textural classification must be, and is an important consideration when interpreting terrestrial and planetary data. The long term goal of this work is to create an objective tool for lava texture classification on Earth and other planetary bodies, as constrained by data resolution.