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Freysteinn Sigmundsson - Research Scientist

Freysteinn Sigmundsson

–

School of Engineering and Natural Sciences

Freysteinn Sigmundsson

Research Scientist

- Geophysics

Location
Askja / N-322
Phone
525 - 4491
Email
fs [at] hi.is

Unit
Institute of Earth Sciences
Website
http://uni.hi.is/fs

Published works

2024

Co-eruptive crustal deformation changes associated with the 2021 Fagradalsfjall eruption (SW-Iceland)
Deformation patterns of the Reykjanes Peninsula unrest 2020-2024, Iceland: evidence for interconnected neighboring volcanic systems
Fracturing and tectonic stress drive ultrarapid magma flow into dikesScience
2021–2023 Unrest and Geodetic Observations at Askja Volcano, IcelandGeophysical Research Letters
Changes in seismicity and observed deformation related to inflation at the Theistareykir high-temperature geothermal field, NE Iceland, in 2023-2024
Continuous Subsidence of Dallol Volcano (Danakil Depression) as a result of magmatic and hydrothermal interaction: Insights from InSAR Observation
The November 2023 Grindavik dike injection in Iceland: Implications for continental rifting, dike formation in extensional tectonic settings, and giant dike swarms
Why not drill into magma to understand the “dynamics and timescales in magmatic reservoirs”?
Geodetic observations of simultaneous rift-scale magma inflow in multiple sills in the Central Afar rift

2023

Recommendations for microgravity campaigns and insight into volcanic subsidence and uplift gained from microgravity data at Askja, Iceland between 1988 - 2022
Joint Bayesian Modeling of Velocity Break Points, Noise Characteristics, and Their Uncertainties in GNSS Time Series: Far‐Field Velocity Anomalies Concurrent With Magmatic Activity in IcelandGeophysical Research Letters
Numerical modeling of Miocene dyke opening in the Cserhát Hills, Hungary
Ongoing unrest at Icelandic volcanoes: What deformation and seismicity patterns to expect leading up to future eruptions
Implementing the Krafla Magma Testbed (KMT): linking volcanology and geothermal research for future hazard and energy solutions
Bayesian modeling of velocity break points in GNSS time series and the effect of noise on their estimation: Did velocity anomalies in the Krafla volcanic system, north Iceland, precede the Bárðarbunga-Holuhraun 2014-2015 rifting episode?
Strain Localization at Volcanoes Undergoing Extension: Investigating Long-term Subsidence at Krafla and Askja in North Iceland
Sudden shallow dyke intrusion at São Jorge Island (Azores) after 60 years of repose
Non-Newtonian magma flow in a growing laccolith and stress induced by dyke formation in a tectonically active region: two examples of advanced multiphysics models.

2022

Quantification of Volcano Deformation caused by Volatile Accumulation and Release
Conduits feeding new eruptive vents at Fagradajsfjall, Iceland, mapped by high-resolution ICEYE SAR satellite in a daily repeat orbit
Variable inflation rate of a magmatic deformation source beneath Aira caldera after the 1914 eruption of Sakurajima volcano: Inferences from a linear Maxwell viscoelastic model constrained by geodetic dataJournal of Volcanology and Geothermal Research
Quantification of Volcano Deformation Caused by Volatile Accumulation and ReleaseGeophysical Research Letters
Quantification of Volcano Deformation caused by Volatile Accumulation and Release
Deformation and seismicity decline before the 2021 Fagradalsfjall eruptionNature
Deformation observations and geodetic modelling during the recent unrest at Askja volcano
Post‐Rifting Relaxation During 2015–2020 Following the Bárðarbunga‐Holuhraun Dike Intrusion and Eruption in IcelandGeophysical Research Letters
Co-eruptive subsidence during the 2021 Fagradalsfjall eruption: geodetic constraints on magma source depths and stress changes
Hybrid Microgravity Monitoring of the Theistareykir Geothermal Reservoir (North Iceland)Pure and Applied Geophysics
Plate Boundary Deformation and Volcano Unrest at the Azores Triple Junction Determined From Continuous GPS Measurements, 2002–2017Journal of Geophysical Research: Solid Earth
Quantification of Volcano Deformation caused by Volatile Accumulation and Release
Evolution of deformation and seismicity on the Reykjanes Peninsula, preceding the 2021 Fagradalsfjall eruption, Iceland
Inflation at Askja, Iceland. New and revisited relative microgravity data.

2021

Ground Deformation After a Caldera Collapse: Contributions of Magma Inflow and Viscoelastic Response to the 2015–2018 Deformation Field Around Bárðarbunga, IcelandJournal of Geophysical Research: Solid Earth
The application of geodetic observations for near-real time monitoring of Icelandic volcanoes
The 2020 volcano-tectonic unrest at Reykjanes Peninsula, Iceland: stress triggering and reactivation of several volcanic systems
3-D Heterogeneous Elastic Crustal Structure for Deformation Models in the Hengill Area, SW Iceland
Plate boundary deformation at the Azores triple junction determined from continuous GPS geodetic measurements, 2002-2017
Beyond elasticity: Are Coulomb properties of the Earth’s crust important for volcano geodesy?
Inflation-Deflation Episodes in the Hengill and Hromundartindur Volcanic Complexes, SW Iceland
Beyond elasticity: Are Coulomb properties of the Earth's crust important for volcano geodesy?Journal of Volcanology and Geothermal Research
Eruption risks from covert silicic magma bodiesGeology
Special issue on Nordic Remote Sensing: Data acquisition, algorithms and applicationsInternational Journal of Applied Earth Observation and Geoinformation

2020

EUROVOLC: Building the European volcanological community and opening access to Research Infrastructures of Volcano Observatories and Volcano Research Institutions
Viscoelastic crustal deformation in the Aira caldera before and after the 1914 eruption of the Sakurajima volcano
Pressure conditions in coupled magma bodies and their evolution during eruptions and caldera collapse: Piton de la Fournaise 2007
Viscoelastic crustal response to magma supply and discharge in the upper crust: Implications for the uplift of the Aira caldera before and after the 1914 eruption of the Sakurajima volcanoEarth and Planetary Science Letters
Operational response and hazards assessment during the 2014-2015 volcanic crisis at Baroarbunga volcano and associated eruption at Holuhraun, IcelandJournal of Volcanology and Geothermal Research
The dynamics of a long-lasting effusive eruption modulated by Earth tidesEarth and Planetary Science Letters
Deformation due to geothermal exploitation at Reykjanes, IcelandJournal of Volcanology and Geothermal Research
Seismic and geodetic response to crustal deformation in Krísuvík volcanic system, southwest Iceland
Geodynamics of Iceland and the signatures of plate spreadingJournal of Volcanology and Geothermal Research
Rapid resurgence of the subglacial Bárdarbunga caldera following collapse in 2014-2015, quantified with repeated Bouguer gravity surveys
Post-eruptive volcano inflation following major magma drainage: Interplay between models of viscoelastic response influence and models of magma inflow at Bárðarbunga caldera, Iceland, 2015-2018
Renewed Inflation of Krafla Caldera, Iceland, since 2018: Sensitivity of Ground Deformation to lateral variation in Earth structure and architecture of the magmatic system explored with the Finite Element Method
Volcanology and Geothermal Resources: Participation of Landsvirkjun in the EUROVOLC project
Unexpected large eruptions from buoyant magma bodies within viscoelastic crustNature Communications
Deformation due to geothermal exploitation at Reykjanes, IcelandJournal of Volcanology and Geothermal Research
Unexpected large eruptions from buoyant magma bodies within viscoelastic crustNature Communications
A half-century of geologic and geothermic investigations in Iceland: The legacy of Kristjan SaemundssonJournal of Volcanology and Geothermal Research

2019

Ground deformation due to steam cap processes at Reykjanes, SW-Iceland: effects of geothermal exploitation inferred from interferometric analysis of Sentinel-1 images 2015-2017Geophysical Journal International
Tracking Magmatic Hydrogen Sulfur Circulations Using Electrical Impedance: Complex Electrical Properties of Core Samples at the Krafla Volcano, IcelandJournal of Geophysical Research: Solid Earth
Icecap and Subglacial Crustal Deformation Inferred From SAR Pixel Tracking: The 2014 Dike Intrusion Episode in the Bárðarbunga Volcanic System, IcelandJournal of Geophysical Research: Solid Earth
Countrywide Observations of Plate Spreading and Glacial Isostatic Adjustment in Iceland Inferred by Sentinel‐1 Radar Interferometry, 2015–2018Geophysical Research Letters
Calderas collapse as magma flows into riftsScience
Electrical resistivity tomography and time-domain induced polarization field investigations of geothermal areas at Krafla, Iceland: comparison to borehole and laboratory frequency-domain electrical observationsGeophysical Journal International
Magma Flow Rates and Temporal Evolution of the 2012–2014 Post‐Eruptive Intrusions at El Hierro, Canary IslandsJournal of Geophysical Research: Solid Earth

2018

The role of smectites in the electrical conductivity of active hydrothermal systems: electrical properties of core samples from Krafla volcano, IcelandGeophysical Journal International
Magma Movements in Volcanic Plumbing Systems and their Associated Ground Deformation and Seismic PatternsVolcanic and Igneous Plumbing Systems: Understanding Magma Transport, Storage, and Evolution in the earth's Crust
Integration of SAR Data Into Monitoring of the 2014-2015 Holuhraun Eruption, Iceland: Contribution of the Icelandic Volcanoes Supersite and the FutureVolc ProjectsFrontiers in Earth Science

2017

Lava field evolution and emplacement dynamics of the 2014-2015 basaltic fissure eruption at Holuhraun, IcelandJournal of Volcanology and Geothermal Research
Deformation at Krafla and Bjarnarflag geothermal areas, Northern Volcanic Zone of Iceland, 1993-2015Journal of Volcanology and Geothermal Research
Three-dimensional glacier surface motion maps at the Gjálp eruption site, Iceland, inferred from combining InSAR and other ice-displacement dataAnnals of Glaciology
Deformation in the Northern Volcanic Zone of Iceland 2008–2014: An interplay of tectonic, magmatic, and glacial isostatic deformationJournal of Geophysical Research: Solid Earth
Evolution of deformation and stress changes during the caldera collapse and dyking at Bardarbunga, 2014-2015: Implication for triggering of seismicity at nearby Tungnafellsjokull volcanoEarth and Planetary Science Letters
From magma ascent to ash generation: investigating volcanic conduit processes by integrating experiments, numerical modeling, and observationsAnnals of Geophysics
Post‐emplacement cooling and contraction of lava flows: InSAR observations and a thermal model for lava fields at Hekla volcano, IcelandJournal of Geophysical Research: Solid Earth
Repeated magmatic intrusions at El Hierro Island following the 2011-2012 submarine eruptionJournal of Volcanology and Geothermal Research
Volcano Geodesy: Recent developments and future challengesJournal of Volcanology and Geothermal Research

2016

Constraints on seasonal load variations and regional rigidity from continuous GPS measurements in Iceland, 1997-2014Geophysical Journal International
New insights into magma plumbing along rift systems from detailed observations of eruptive behavior at Axial volcanoGeophysical Research Letters
Continuous subsidence in the Thingvellir rift graben, Iceland: Geodetic observations since 1967 compared to rheological models of plate spreadingJournal of Geophysical Research: Solid Earth
Gradual caldera collapse at Bardarbunga volcano, Iceland, regulated by lateral magma outflowScience

2015

Kilometer-scale Kaiser effect identified in Krafla volcano, IcelandGeophysical Research Letters
Tectonic and volcanic deformation at Sao Miguel Island, Azores, observed by continuous GPS analysis 2008-13Geological Society, London, Memoirs
Forecasting the path of a laterally propagating dikeJournal of Geophysical Research: Solid Earth
Segmented lateral dyke growth in a rifting event at Bardarbunga volcanic system, IcelandNature

2014

Stress transfer between magma bodies: Influence of intrusions prior to 2010 eruptions at Eyjafjallajokull volcano, IcelandJournal of Geophysical Research: Solid Earth
Geodetic measurements and numerical models of rifting in Northern Iceland for 1993-2008Geophysical Journal International
Volcanic plume height correlated with magma-pressure change at Grimsvotn Volcano, IcelandNature Geoscience
InSAR observations and models of crustal deformation due to a glacial surge in IcelandGeophysical Journal International

2013

FUTUREVOLC: A EUROPEAN VOLCANOLOGICAL SUPERSITE OBSERVATORY IN ICELAND, A MONITORING SYSTEM AND NETWORK FOR THE FUTUREIEEE International Geoscience and Remote Sensing Symposium - IGARSS
Iceland rising: Solid Earth response to ice retreat inferred from satellite radar interferometry and visocelastic modelingJournal of Geophysical Research: Solid Earth
Geodetic data shed light on ongoing caldera subsidence at Askja, IcelandBulletin of Volcanology
New insights into volcanic activity from strain and other deformation data for the Hekla 2000 eruptionJournal of Volcanology and Geothermal Research

2012

Remote Sensing of Volcanic Hazards and Their PrecursorsProceedings of the IEEE
Post-glacial rebound and asthenosphere viscosity in IcelandGeophysical Research Letters
Subsidence of Askja caldera 2000–2009: Modelling of deformation processes at an extensional plate boundary, constrained by time series InSAR analysisJournal of Volcanology and Geothermal Research
Volcano deformation at active plate boundaries: Deep magma accumulation at Hekla volcano and plate boundary deformation in south IcelandJournal of Geophysical Research: Solid Earth
Geophysical constraints on the dynamics of spreading centres from rifting episodes on landNature Geoscience

2011

Increased capture of magma in the crust promoted by ice-cap retreat in IcelandNature Geoscience
Magma flow directions inferred from field evidence and magnetic fabric studies of the Streitishvarf composite dike in east IcelandJournal of Volcanology and Geothermal Research
Deep magma storage at Hekla volcano, Iceland, revealed by InSAR time series analysisJournal of Geophysical Research: Solid Earth

2010

Climate effects on volcanism: influence on magmatic systems of loading and unloading from ice mass variations, with examples from IcelandPhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Influence of surface load variations on eruption likelihood: application to two Icelandic subglacial volcanoes, Grímsvötn and KatlaGeophysical Journal International
The 2008 May 29 earthquake doublet in SW IcelandGeophysical Journal International
Intrusion triggering of the 2010 Eyjafjallajokull explosive eruptionNature
Katla and Eyjafjallajokull VolcanoesDevelopments in Quaternary Science
Develop instruments to monitor volcanic ash falloutNature
Pressure sources versus surface loads: Analyzing volcano deformation signal composition with an application to Hekla volcano, IcelandGeophysical Research Letters
Overview of results from continuous GPS observations in Iceland from 1995 to 2010Jokull

2009

Rheologic controls on inter-rifting deformation of the Northern Volcanic Zone, IcelandEarth and Planetary Science Letters

2008

Will present day glacier retreat increase volcanic activity? Stress induced by recent glacier retreat and its effect on magmatism at the Vatnajokull ice cap, IcelandGeophysical Research Letters
The dynamic geology of IcelandJokull
Three-dimensional mechanical models for the June 2000 earthquake sequence in the South Iceland seismic zoneTectonophysics
Multiple volcano deformation sources in a post-rifting period: 1989–2005 behaviour of Krafla, Iceland constrained by levelling, tilt and GPS observationsJournal of Volcanology and Geothermal Research
Iceland: a window on North-Atlantic divergent plate tectonics and geologic processesEpisodes
Nordic geoscience and the 3rd international geological congress: IntroductionEpisodes
Natural hazards in Nordic countriesEpisodes
Seismic and geodetic insights into magma accumulation at Katla subglacial volcano, Iceland: 1999 to 2005Journal of Geophysical Research: Solid Earth

2007

Crustal deformation associated with the 1996 Gjalp subglacial eruption, Iceland: InSAR studies in affected areas adjacent to the Vatnajokull ice capEarth and Planetary Science Letters
Discriminating volcano deformation due to magma movements and variable surface loads:: application to Katla subglacial volcano, IcelandGeophysical Journal International
Glacio-isostatic deformation around the Vatnajokull ice cap, Iceland, induced by recent climate warming: GPS observations and finite element modelingJournal of Geophysical Research: Solid Earth
Controlling factors on earthquake swarms associated with magmatic intrusions; Constraints from IcelandJournal of Volcanology and Geothermal Research

2006

Magma does the splitsNature
Deformation studies at Furnas and Sete Cidades Volcanoes (Sao Miguel Island, Azores). Velocities and further investigationsGeophysical Journal International
Icelandic rhythmics: Annual modulation of land elevation and plate spreading by snow loadGeophysical Research Letters
Integration of micro-gravity and geodetic data to constrain shallow system mass changes at Krafla Volcano, N IcelandBulletin of Volcanology
1983–2003 decaying rate of deflation at Askja caldera: Pressure decrease in an extensive magma plumbing system at a spreading plate boundaryBulletin of Volcanology
Deflation of the Askja volcanic system: Constraints on the deformation source from combined inversion of satellite radar interferograms and GPS measurementsJournal of Volcanology and Geothermal Research
Current plate movements across the Mid-Atlantic Ridge determined from 5 years of continuous GPS measurements in IcelandJournal of Geophysical Research: Atmospheres
Temporal development of the 1999 intrusive episode in the Eyjafjallajokull volcano, Iceland, derived from InSAR imagesBulletin of Volcanology
Probabilistic model for eruptions and associated flood events in the Katla caldera, IcelandComputational Geosciences
Volcano geodesy and magma dynamics in IcelandJournal of Volcanology and Geothermal Research

2005

Geodetic GPS measurements in south Iceland: Strain accumulation and partitioning in a propagating ridge systemJournal of Geophysical Research: Solid Earth
Net gravity decrease at Askja volcano, Iceland: constraints on processes responsible for continuous caldera deflation, 1988–2003Journal of Volcanology and Geothermal Research

2004

The 1996 eruption at Gj�lp, Vatnaj�kull ice cap, Iceland: efficiency of heat transfer, ice deformation and subglacial water pressureBulletin of Volcanology
Satellite radar interferometry 1993-1999 suggests deep accumulation of magma near the crust-mantle boundary at the Krafla volcanic system, IcelandGeophysical Research Letters
InSAR based sill model links spatially offset areas of deformation and seismicity for the 1994 unrest episode at Eyjafjallajökull volcano, IcelandGeophysical Research Letters

2003

Fault slip distribution of two June 2000 M(w)6.5 earthquakes in South Iceland estimated from joint inversion of InSAR and GPS measurementsEarth and Planetary Science Letters
Triggered fault slip on June 17, 2000 on the Reykjanes Peninsula, SW-Iceland captured by radar interferometryGeophysical Research Letters
Recent unrest and magma movements at Eyjafjallajokull and Katla volcanoes, IcelandJournal of Geophysical Research: Solid Earth
Deformation of Grímsvötn volcano, Iceland: 1998 eruption and subsequent inflationGeophysical Research Letters

2002

Three-dimensional surface motion maps estimated from combined interferometric synthetic aperture radar and GPS dataJournal of Geophysical Research: Solid Earth
Surface effects of faulting and deformation resulting from magma accumulation at the Hengill triple junction, SW Iceland, 1994-1998Journal of Volcanology and Geothermal Research
Unwrapping ground displacement signals in satellite radar interferograms with aid of GPS data and MRF regularizationIEEE Transactions on Geoscience and Remote Sensing

2001

Coseismic interferograms of two M-S=6.6 earthquakes in the South Iceland Seismic Zone, June 2000Geophysical Research Letters
Crustal deformation at the oblique spreading Reykjanes Peninsula, SW Iceland: GPS measurements from 1993 to 1998Journal of Geophysical Research: Solid Earth

2000

Continuous deflation of the Askja caldera, Iceland, during the 1983-1998 noneruptive periodJournal of Geophysical Research: Solid Earth
Comment on " Volume of magma accumulation or withdrawal estimated from surface uplift or subsidence, with application to the 1960 collapse of Kīlauea volcano" by P. T. Delaney and D. F. McTigueBulletin of Volcanology
Crustal deformation near Hengill volcano, Iceland 1993-1998: Coupling between magmatic activity and faulting inferred from elastic modeling of satellite radar interferogramsJournal of Geophysical Research: Solid Earth

1999

Opening of an eruptive fissure and seaward displacement at Piton De La Fournaise Volcano measured by RADARSAT satellite radar interferometryGeophysical Research Letters
Low rates of deformation of the Furnas and Fogo Volcanoes, São Miguel, Azores, observed with the Global Positioning System, 1993–1997Journal of Volcanology and Geothermal Research

1998

Sources of crustal deformation associated with the Krafla, Iceland, eruption of September 1984Geophysical Research Letters
Post-eruptive gravity changes from 1990 to 1996 at Krafla volcano, IcelandJournal of Volcanology and Geothermal Research

1997

Readjustment of the Krafla Spreading Segment to crustal rifting measured by satellite radar interferometryGeophysical Research Letters
The 1994-1995 seismicity and deformation at the Hengill triple junction, Iceland: Triggering of earthquakes by minor magma injection in a zone of horizontal shear stressJournal of Geophysical Research: Solid Earth
Extension across a divergent plate boundary, the eastern Volcanic Rift Zone, south Iceland, 1967-1994, observed with GPS and electronic distance measurementsJournal of Geophysical Research: Solid Earth
Ice–volcano interaction of the 1996 Gjálp subglacial eruption, Vatnajökull, IcelandNature
Crustal Deformation from 1992 to 1995 at the Mid-Atlantic Ridge, Southwest Iceland, Mapped by Satellite Radar InterferometryScience

1995

PLATE BOUNDARY DEFORMATION AND CONTINUING DEFLATION OF THE ASKJA VOLCANO, NORTH ICELAND, DETERMINED WITH GPS, 1987-1993Bulletin of Volcanology
SLOW INFLATION OF THE FURNAS VOLCANO, SAO-MIGUEL, AZORES, SUGGESTED FROM INITIAL LEVELING AND GLOBAL POSITIONING SYSTEM MEASUREMENTSGeophysical Research Letters
Rift-transform kinematics in south Iceland: Deformation from Global Positioning System measurements, 1986 to 1992Journal of Geophysical Research: Solid Earth

1994

Strain accumulation 1986-1992 across the Reykjanes Peninsula Plate Boundary, Iceland, determined from GPS measurementsGeophysical Research Letters

1992

Glacio-isostatic crustal movements caused by historical volume change of the Vatnajökull Ice Cap, IcelandGeophysical Research Letters
Magma chamber deflation recorded by the global positioning system: The Hekla 1991 EruptionGeophysical Research Letters
Tectonic implications of the 1989 Afar Earthquake sequenceGeophysical Research Letters

Keywords for Specialisation:

Crustal Deformation