Graduation Year

2025

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Geology

Major Professor

Charles Connor, Ph.D.

Co-Major Professor

Mel Rodgers, Ph.D.

Committee Member

Elisabeth Gallant, Ph.D.

Keywords

deflation, inflation, lava rise, lumps, pāhoehoe, ‘a‘ā

Abstract

Basaltic lava flow eruptions can impact vast areas, profoundly altering the landscape. Although many past eruptions have gone unobserved by scientists, they often leave behind substantial deposits that preserve key elements of the eruption’s history. By studying lava textures and the overall structure of lava flows, we can reconstruct the specific conditions that occurred during the eruption and contributed to the final morphology of the lava flows. Hell’s Half Acre is a large, well-preserved basaltic lava flow in the Eastern Snake River Plain, containing a variety of significant geological features resulting from its distinctive eruption history. This thesis examines a unique small-scale lava texture I have coined “lava lumps,” as well as large-scale structures that shape the present-day morphology of a part of the Hell’s Half Acre lava flow. Colleagues and I employed texture analyses, drone-borne lidar, feature mapping, and integrated Structure from Motion (SfM) techniques to gain a comprehensive understanding of the processes responsible for lava emplacement. Quantitative and qualitative descriptions, combined with mapping, enabled a detailed characterization of the lumps. The lidar data facilitated the creation of high-resolution point clouds, digital elevation models, and orthophotos, along with a geological structure interpretation map highlighting key structures within this section of the flow. It is hypothesized that the formation of the lumps and a large collapse depression are a result of the deflation of a lava rise near the flow’s northern edge. This large-scale process triggered small- and large-scale responses within the flow, leading to the formation of distinctive textural and structural features unique to this phenomenon. Our study of Hell’s Half Acre provides valuable insights into the dynamic nature of basaltic lava flows, contributing to our understanding of how intricate processes shape volcanic landscapes. These findings have broader implications for refining lava flow hazard models and deepening our understanding of volcanic processes, both on Earth and across other planetary bodies.

Included in

Geology Commons

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