Coffee Hour with Peter La Femina: Up, Up, and Away: Interactions between Magmatism, Tectonics, and Climate in Iceland

Friday, December 1, 2017 - 3:30pm
Refreshments are offered in 319 Walker Building at 3:30 p.m. The lecture begins in 112 Walker Building at 4:00 p.m

uplift across Iceland from mass loss from ice caps

About the talk

Iceland provides a unique and dynamic environment to investigate the geodynamics of a mid-ocean ridge, including ridge-transform and magma-tectonic interactions and the role of central volcano – fissure swarm systems in accommodating divergent plate motion. We have been studying the deformation of the Hekla central volcano to investigate magmatic processes and the interaction between central volcanoes and the mid-ocean ridge system. In addition to magmatic and tectonic systems, Iceland is home to Europe’s largest icecap, Vatnajökull, as well as several smaller ice caps. Significant historical mass loss from these ice caps has resulted in extensive uplift across Iceland.  We present a new horizontal and vertical velocity field based on GPS data from 1994 to the present.  This velocity field indicates, 1) North America – Eurasia plate motion dominates the horizontal signal; 2) broad uplift across all of Iceland, except in the northwest fjords where there is subsidence; 3) up to 3 cm/yr, but on average 2 cm/yr, uplift west and southwest of Vatnajökull; and 4) a decrease in uplift with distance away from Vatnajökull.  The position time series also suggest an increase in vertical velocities starting around 2004, suggesting an increase in mass loss.  This extensive uplift signal impacts our estimation of secular plate motions and long-term volcanic deformation.  We investigate the effects of the uplift signal on estimating plate motion models and volcano deformation at Hekla volcano using a finite element model for glacial mass loss and analytical models of volcano deformation.  Residual vertical velocities indicate, 1) subsidence at less than 5 mm/yr along the two main ridge segments in south Iceland; 2) constant subsidence of the Torfajökull caldera at up to 8 mm/yr over the last two decades; and 3) continuous uplift of Hekla volcano of 5 mm/yr since its last eruption in 2000. Modeling of the deformation signal at Hekla volcano indicates a deep-seated magma chamber at ~20 km depth.

About the speaker

Peter LaFeminaPeter La Femina is an associate professor of geosciences at Penn State. He holds a Ph.D. in Marine Geology and Geophysics from the University of Miami – Rosenstiel School of Marine and Atmospheric Sciences (RSMAS), an M.Sc. in Geology from Florida International University, and a B.A. in Geology from Hartwick College. Prior to joining the Department of Geosciences at Penn State, he was a post-doctoral researcher at RSMAS, and held the post of scientist with the Southwest Research Institute's Center for Nuclear Waste Regulatory Analyses. In addition, La Femina has served in various executive positions, including chairperson of the Board of Directors, UNAVCO, Inc. (a non-profit university-governed consortium that facilitates geoscience research and education using Geodesy). In his geodynamics research, he integrates geophysical measurements with numerical modeling to study active tectonic, magmatic and volcanic processes, with the goals of improving our knowledge of fault systems during the earthquake cycle, the geodynamics of plate boundary zone deformation, the short and long-term interaction of magmatic and fault systems, precursors to volcanic activity, and eruption dynamics. His research on plate tectonics and volcanism in Iceland was featured in the 2009 documentary "How the Earth was Made: Iceland" on the History Channel, and the 2010 BBC documentary "History of Science". La Femina's awards have included the National Science Foundation's Faculty Early Career Development Award and the Walton Smith Award bestowed for the single outstanding Ph.D. dissertation at the RSMAS, University of Miami. He has authored over 39 peer-reviewed publications.

Suggested reading

Volcano deformation at active plate boundaries: Deep magma accumulation at Hekla volcano and plate boundary deformation in south Iceland (PDF)

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