24 Undergraduate Research Posters
This poster session highlights geoscience research conducted and presented by undergraduate students. Abstracts must be written by students (but may include non-student co-authors). Research topics may include any area of the earth sciences.
Thursday, 23 April 2026
8:00 AM - 5:30 PM
LMH, 5th Floor Chapel
Analysis of Crystal and Vesicle Textures to Investigate Eruption Triggers at Volcán Cosigüina, Nicaragua
Paper number: 24-3
Program: Technical Sessions
Time: 8:15 AM – 8:15 AM
Authors
Abstract
Textural analysis of crystals and vesicles in volcanic tephra provides key insights into magma dynamics, including degassing, crystallization, and eruption triggers. Characterizing these processes is essential for forecasting volcanic activity and improving hazard mitigation strategies. This study aims to identify the pre-eruptive processes that triggered eruption Cos-H at Volcán Cosigüina, an intermediate composite volcano on Nicaragua’s northwestern peninsula that preserves well-zoned fall deposits from more than fifteen explosive eruptions.
The primary research goal is to determine how crystallization and volatile exsolution influenced pre- and syn-eruptive conditions across the compositional transition from dacite (66.6–68.21 wt% SiO₂) to andesite (60.43–61.83 wt% SiO₂). Lapilli from four horizons—10 and 20 cm above and below the compositional transition—were analyzed using backscattered electron (BSE) imaging and ImageJ software to generate crystal and vesicle size distributions, providing a record of pre-eruptive crystallization and degassing behavior.
Results reveal a rapid, nucleation-dominant crystallization stage across all mineral phases and variations in vesicle nucleation between dacitic and andesitic deposits. These observations support overpressurization driven by crystallization-induced volatile exsolution and filter-pressing as the eruption trigger. Overall, this work identifies crystallization-driven overpressure as a plausible mechanism for initiating explosive volcanism at Cosigüina and contributes to a broader understanding of eruption mechanisms in compositionally zoned magmatic systems.
Geological Society of America Abstracts with Programs. Vol. 58, No. 3
doi: 10.1130/abs/2026CD-410822
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