Iceland is a laboratory for studying the solid Earth response to changes in surface loading because of the underlying hot mantle and thin uppermost elastic layer (relating to mantle plume – oceanic ridge interaction), and rapid major ice mass and magma load changes. Glacial isostatic adjustment (GIA) following the end of the last glaciation in Iceland is inferred to have been complete in coastal areas about 9000 years ago. Nevertheless, GPS-measurements show the area around Vatnajökull, in SE Iceland, is uplifting at present at a rate of over 30 mm/yr, interpreted as the GIA response to present retreat of ice caps since 1890. These deformation trends have also been mapped by interferometric analysis of synthetic aperture radar images (InSAR). Influence from annual load changes are superimposed on the general trends, and can be used to constrain the annual mass balance variations of Icelandic ice caps. The elastic structure has furthermore been constrained from response to redistribution of ice mass during a glacial surge. We demonstrate that InSAR studies using data from the Sentinel-1 satellites, provide constraints on load induced deformation of high spatial resolution and can be integrated into future modeling efforts. Additional constraints on the visco-elastic structure under Iceland are provided by: i) Post-seismic response, observed following the 2000 and 2008 South Iceland earthquakes, ii) Post-rifting adjustment in central Iceland following major dyking event and caldera collapse in Bárðarbunga in 2014-2015, which at present is responsible for ongoing transient deformation near Bárðarbunga, iii) Measurements of sea-level changes, that have, however, been limited in Iceland. Predictions of sea level change in Iceland using global GIA models, which do not take into account the specific Earth structure and low viscosity under Iceland, provide unrealistic predictions and limit the usefulness of such models for Iceland. Well constrained models of Earth structure and load changes help to understand the various effects of the present unloading on magmatism in Iceland, including increased mantle melting in response to unloading, variation in magma transfer and storage in the crust, and instability of magma bodies at shallow depths beneath Iceland.
Interplay of surface loading and glacial isostatic adjustment in Iceland
Carolina Pagli;
2017-01-01
Abstract
Iceland is a laboratory for studying the solid Earth response to changes in surface loading because of the underlying hot mantle and thin uppermost elastic layer (relating to mantle plume – oceanic ridge interaction), and rapid major ice mass and magma load changes. Glacial isostatic adjustment (GIA) following the end of the last glaciation in Iceland is inferred to have been complete in coastal areas about 9000 years ago. Nevertheless, GPS-measurements show the area around Vatnajökull, in SE Iceland, is uplifting at present at a rate of over 30 mm/yr, interpreted as the GIA response to present retreat of ice caps since 1890. These deformation trends have also been mapped by interferometric analysis of synthetic aperture radar images (InSAR). Influence from annual load changes are superimposed on the general trends, and can be used to constrain the annual mass balance variations of Icelandic ice caps. The elastic structure has furthermore been constrained from response to redistribution of ice mass during a glacial surge. We demonstrate that InSAR studies using data from the Sentinel-1 satellites, provide constraints on load induced deformation of high spatial resolution and can be integrated into future modeling efforts. Additional constraints on the visco-elastic structure under Iceland are provided by: i) Post-seismic response, observed following the 2000 and 2008 South Iceland earthquakes, ii) Post-rifting adjustment in central Iceland following major dyking event and caldera collapse in Bárðarbunga in 2014-2015, which at present is responsible for ongoing transient deformation near Bárðarbunga, iii) Measurements of sea-level changes, that have, however, been limited in Iceland. Predictions of sea level change in Iceland using global GIA models, which do not take into account the specific Earth structure and low viscosity under Iceland, provide unrealistic predictions and limit the usefulness of such models for Iceland. Well constrained models of Earth structure and load changes help to understand the various effects of the present unloading on magmatism in Iceland, including increased mantle melting in response to unloading, variation in magma transfer and storage in the crust, and instability of magma bodies at shallow depths beneath Iceland.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
