Volcanic investigations of the Puna Ridge, Hawai′i: relations of lava flow morphologies and underlying slopes

Previous investigators have demonstrated that submarine lava flow morphologies are the result of a complex interplay between lava rheology, effusion rate, and underlying slope. Here, we specifically investigate the relation between underlying slope and submarine lava flow morphology along three study sites of the Puna Ridge, Kilauea Volcano, Hawai′i. Using Electronic Still Camera (ESC) images and detailed bathymetry collected by ARGO-II, we can compare the lava morphology and the associated underlying slope. Our results indicate that rubble is most common on the steepest slopes (≥25°) and that pillowed and lobate flows dominate on slopes ≤20°. Sheet flows were only seen on relatively shallow slopes (≤15°). These observations disagree with the results obtained from previous laboratory analog experiments, suggesting that the laboratory results are directly applicable for lavas emplaced on relatively low (<15°) underlying slopes. We conclude from our results that the tensile strength of the basaltic lava crust plays a much greater role in determining submarine lava flow morphology than previously thought.