Textural insights into the evolving lava dome cycles at Santiaguito lava dome, Guatemala. 1 Emma Rhodes1*, Ben Kennedy1, Yan Lavallée2, Adrian Hornby2, Matt Edwards1, Gustavo 2 Chigna3 3 1Geological Sciences, University of Canterbury, Private Bag 4800, 8140 Christchurch, New Zealand 4 2 Department of Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool L69 3GP, 5 UK 6 3Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hydrologia (INSIVUMEH), 7a 7 Avenue 14‐57, Zone 13, Guatemala City, Guatemala 8 * Correspondence: 9 Emma Rhodes 10
[email protected] 11 Keywords: lava dome1, Santiaguito2, pore structure3, effusion rate4, degassing5. 12 Abstract 13 The structures and textures preserved in lava domes reflect underlying magmatic and eruptive 14 processes, and may provide evidence of how eruptions initiate and evolve. This study explores the 15 remarkable cycles in lava extrusion style produced between 1922 and 2012 at the Santiaguito lava 16 dome complex, Guatemala. By combining an examination of eruptive lava morphologies and textures 17 with a review of historical records, we aim to constrain the processes responsible for the range of 18 erupted lava type and morphologies. The Santiaguito lava dome complex is divided into four domes 19 (El Caliente, La Mitad, El Monje, El Brujo), containing a range of proximal structures (e.g. spines) 20 from which a series of structurally contrasting lava flows originate. Vesicular lava flows (with a’a 21 like, yet non-brecciated flow top) have the highest porosity with interconnected spheroidal pores and 22 may transition into blocky lava flows. Blocky lava flows are high volume and texturally variable with 23 dense zones of small tubular aligned pore networks and more porous zones of spheroidal shaped 24 pores.