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Linking Small-Scale Textural Features to Large-Scale Volcanic Processes: A Study of Hell's Half Acre Lava Flow

Rachel Bakowski1, Charles Connor1, Mel Rodgers1, Rocco Malservisi1, Robert Van Alphen1, Lis Gallant2

  • Affiliations:  1School of Geosciences, University of South Florida, Tampa, United States of America; 2Department of Geology, University of Hawaiʻi at Hilo, Hilo, United States of America 

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 8

  • Programme No: 3.7.15

  • Theme 3 > Session 7

Abstract

Lava flow eruptions from new vents in distributed volcanic fields can impact vast areas during relatively brief eruptions. Since these eruptions are rarely observed, observations of lava texture, overall flow structure, and models of emplacement processes provide crucial information to assess hazards and risks of these eruptions. The Holocene Hell's Half Acre eruption on the Eastern Snake River Plain (ID, USA), covers approximately 430 km2. We conducted texture analysis, drone-borne LiDAR, mapping, and surface geophysical studies to better understand emplacement processes on one part of the lava flow. Quantitative measurements and qualitative descriptions were collected to characterize a unique surface texture we refer to as "lava lumps." These lumps, found in specific areas within the flow, were mapped utilizing the drone-borne LiDAR. A total of 309,152 m2 was surveyed, enabling the generation of an elevation map that revealed a bimodal distribution of elevation across the flow. Further analysis led to the creation of a geological map highlighting the various structures present in this area of the flow. Supplemental electromagnetic data were gathered using ground-penetrating radar to measure lava flow thickness and investigate the internal structure at varying elevations. Our analysis of such a small area of the flow provided insights into larger-scale processes correlated with the eruption's complexity. The formation of the lumps and associated small-scale textures corresponds to the timing of lava rise deflation near the flow's northern edge. This larger-scale process initiated smaller-scale responses within the flow, giving rise to distinctive textural features unique to this phenomenon.