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Formation of the donut-shaped lava dome at Nevado del Ruiz volcano studied using TerraSAR-X, thermal imagery, and analogue modelling

Thomas R. Walter1, Ai Lun1, Erica De Paolo2, Francesco Massimetti4, 3, Diego Coppola3, Marco Laiolo3

  • Affiliations: 1GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany; 2Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, Catania Italy; 3Department of Earth Sciences, University of Torino, Italy; 4Instituto de Geofísica, Vulcanología, Universidad Nacional Autónoma de México

  • Presentation type: Poster

  • Presentation time: Friday 16:30 - 18:00, Room Poster Hall

  • Poster Board Number: 29

  • Programme No: 2.3.15

  • Theme 2 > Session 3

Abstract

Lava domes often develop flat-topped or even ring-shaped morphologies that are only poorly understood. The Nevado del Ruiz volcano in Colombia, notorious for its catastrophic 1986 eruption, has been experiencing a new episode of dome extrusion in 2016-2017. Here we exploit high-resolution spotlight synthetic aperture radar data acquired by the TerraSAR-X satellite, allowing us to monitor the dome at regular intervals. We compare the data to thermal anomaly data, and trace the ~400 m diameter dome growth. Specifically we can distinguish (i) an initial radial growth and thermal peaks both at the dome's apex and its periphery, and (ii) a cooling, flattening and subsidence of the dome's apex, forming a donut-shaped dome feature.  To better understand the transition from growth and expansion to subsidence and contraction, we conducted analog experiments simulating conduit extrusion leading to dome formation followed by conduit withdrawal. Experimental results show during dome extrusion a vertical growth and mainly radial expansion, accompanied by oversteepening of the outer rim and localized peripheral collapses. In contrast, conduit withdrawal causes the apex of the dome to contract and subside, forming localized concentric fault traces. We conjecture that areas of expansion and collapse amphitheaters corresponded to zones of intense thermal anomalies and dome growth, whereas areas of contraction correlated with cooler regions, signifying a transition from dome growth to cooling and subsidence. This study underscores the importance of exploring the evolution of lava domes and the formation of donut-shaped morphology that may be similarly found at dome building volcanoes elsewhere.