Háskóli Íslands

Ph.D. student: Siqi Li

Dissertation title: Ground deformation caused by viscoelastic relaxation and its role in the 2015-2021 post-eruptive period at the Bárðarbunga volcanic system, Iceland

Opponents:
Dr. Fred F. Pollitz, Research Geophysicist in U.S. Geological Survey, USA
Dr. Yang Liao, Assistant Scientist in Woods Hole Oceanographic Institution, USA

Advisor: Dr. Freysteinn Sigmundsson, Research Scientist at the Institute of Earth Sciences, University of Iceland

Doctoral committee: 
Dr. Halldór Geirsson, Associate Professor at the Faculty of Earth Sciences, University of Iceland
Dr. Andrew Hooper, Professor at the University of Leeds, UK

Chair of Ceremony:  Dr. Andri Stefánsson, Professor and Head of the Faculty of Earth Sciences, University of Iceland

When and where: 6. December at 14:00 in the Aula

Abstract:
Post-eruptive deformation following volcanic eruptions may originate from continued magma movements or reflect delayed and continued Earth adjustment due to co-eruptive events, often referred to as viscoelastic relaxation. Post-eruptive deformation can continue for years, and it is challenging to reveal the details of the underlying processes. In this PhD project, the ground deformation in a post-eruptive period at the Bárðarbunga volcanic system is mapped using Global Navigation Satellite System (GNSS) geodesy and Interferometric analysis of Synthetic Aperture Radar satellite images (InSAR).

The Bárðarbunga volcanic system is a laboratory area for this study because of the large-scale magma transfer during an eruption in 2014-2015, lasting six months. In our study area, the corrected average velocity field observed by GNSS and InSAR suggests horizontal movements away from the caldera and the dike in the post-eruptive period.

Viscoelastic relaxation and/or renewed magma inflow can explain the observed deformation around the Bárðarbunga caldera. It is hard to tell the difference between the processes by only comparing the average velocity field. The post-eruptive deformation around the Bárðarbunga-Holuhraun dike can be explained with a two-layer viscoelastic model. To better understand the difference between viscoelastic relaxation and magma inflow, it is explored if the stress field and displacement time series differ. With a better spatial and temporal geodetic monitoring network, displacement time series may be able to help distinguish the differences between the viscoelastic relaxation and renewed magma inflow processes following a major magma drainage event.

About the doctoral candidate

Siqi Li was born in 1992 in Renqiu, China. She obtained her bachelor’s degree from Chengdu University of Technology in Exploration Techniques & Engineering in 2015. In 2016, she got her master’s degree in Earth Physics from the University of Edinburgh. She came to Iceland in 2017 and began her PhD study of ground deformation at the Bárðarbunga volcano. She is fascinated by Icelandic nature and volcanoes. She enjoys hiking and exploring Iceland when the weather is good.

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