scholarly journals Influence of 3D Earth structure on Glacial Isostatic Adjustment in the Russian Arctic

2020 ◽  
Author(s):  
Tanghua Li ◽  
Nicole Khan ◽  
Alisa Baranskaya ◽  
Timothy Shaw ◽  
W Richard Peltier ◽  
...  
Keyword(s):  
Earth Structure ◽  
Glacial Isostatic Adjustment ◽  
Russian Arctic ◽  
Isostatic Adjustment ◽  
3D Earth Structure

scholarly journals Joint inversion estimate of regional glacial isostatic adjustment in Antarctica considering a lateral varying Earth structure (ESA STSE Project REGINA)

2017 ◽  
Vol 211 (3) ◽  
pp. 1534-1553 ◽  
Author(s):  
Ingo Sasgen ◽  
Alba Martín-Español ◽  
Alexander Horvath ◽  
Volker Klemann ◽  
Elizabeth J Petrie ◽  
...  
Keyword(s):  
Joint Inversion ◽  
Earth Structure ◽  
Glacial Isostatic Adjustment ◽  
Isostatic Adjustment

Glacial Isostatic Adjustment with 3D Earth models: A comparison of case studies of deglacial relative sea level records of North America and Russian Arctic

2020 ◽  
Author(s):  
Tanghua Li ◽  
Nicole Khan ◽  
Simon Engelhart ◽  
Alisa Baranskaya ◽  
Peltier William ◽  
...  
Keyword(s):  
North America ◽  
Sea Level ◽  
3D Models ◽  
Viscosity Model ◽  
Glacial Isostatic Adjustment ◽  
Russian Arctic ◽  
Scaling Factors ◽  
Relative Sea Level ◽  
Isostatic Adjustment ◽  
Best Fit

<p>The Canadian landmass of North America and the Russian Arctic were covered by large ice sheets during the Last Glacial Maximum, and have been key areas for Glacial Isostatic Adjustment (GIA) studies. Previous GIA studies have applied 1D models of Earth’s interior viscoelastic structure; however, seismic tomography, field geology and recent studies reveal the potential importance of 3D models of this structure. Here, using the latest quality-controlled deglacial sea-level databases from North America and the Russian Arctic, we investigate the effects of 3D structure on GIA predictions. We explore scaling factors in the upper mantle (<em>β<sub>UM</sub></em>) and lower mantle (<em>β<sub>LM</sub></em>) and the 1D background viscosity model (<em>η<sub>o</sub></em>) with predictions of of the ICE-6G_C (VM5a) glaciation/deglaciation model of Peltier et al (2015, JGR) in these two regions, and compare with the best fit 3D viscosity structures.</p><p>We compute gravitationally self-consistent relative sea-level histories with time dependent coastlines and rotational feedback using both the Normal Mode Method and Coupled Laplace-Finite Element Method. A subset of 3D GIA models is found that can fit the deglacial sea-level databases for both regions. These databases cover both the near and intermediate field regions. However, North America and Russian Arctic prefer different 3D structures (i.e., combinations of (<em>η<sub>o</sub>, β<sub>UM</sub>, β<sub>LM</sub></em>)) to provide the best fits. The Russian Arctic database prefers a softer background viscosity model (<em>η<sub>o</sub></em>), but larger scaling factors (<em>β<sub>UM</sub>, β<sub>LM</sub></em>) than those preferred by the North America database.</p><p>Outstanding issues include the uncertainty of the history of local glaciation history. For example, preliminary modifications of the ice model in Russian Arctic reveal that the misfits of 1D models can be significantly reduced, but still fit less well than the best fit 3D GIA model.An additional issue concerns the extent to which the 3D models are able to improve both fits in North America and Russian Arctic when compared with 1D internal structure (ICE-6G_C VM5a & ICE-7G VM7), will be assessed in a preliminary fashion.</p>

scholarly journals Impact of 3-D Earth structure on Fennoscandian glacial isostatic adjustment: Implications for space-geodetic estimates of present-day crustal deformations

2006 ◽  
Vol 33 (13) ◽  
Author(s):  
Pippa Whitehouse ◽  
Konstantin Latychev ◽  
Glenn A. Milne ◽  
Jerry X. Mitrovica ◽  
Roblyn Kendall
Keyword(s):  
Earth Structure ◽  
Glacial Isostatic Adjustment ◽  
Isostatic Adjustment

scholarly journals Decontaminating tide gauge records for the influence of glacial isostatic adjustment: The potential impact of 3-D Earth structure

2006 ◽  
Vol 33 (24) ◽  
Author(s):  
Roblyn A. Kendall ◽  
Konstantin Latychev ◽  
Jerry X. Mitrovica ◽  
Jonathan E. Davis ◽  
Mark E. Tamisiea
Keyword(s):  
Tide Gauge ◽  
Earth Structure ◽  
Glacial Isostatic Adjustment ◽  
Tide Gauge Records ◽  
Isostatic Adjustment ◽  
Potential Impact

Glacial isostatic adjustment of the pacific coast of North America: The Influence of lateral earth structure

2021 ◽  
Author(s):  
Maryam Yousefi ◽  
Glenn A Milne ◽  
Konstantin Latychev
Keyword(s):  
North America ◽  
Data Model ◽  
Pacific Coast ◽  
3D Structure ◽  
Earth Structure ◽  
Glacial Isostatic Adjustment ◽  
Isostatic Adjustment ◽  
The Pacific ◽  
Seismic Models ◽  
Lateral Structure

Summary The Pacific Coast of Central North America is a geodynamically complex region which has been subject to various geophysical processes operating on different time scales. Glacial isostatic adjustment (GIA), the ongoing deformational response of the solid Earth to past deglaciation, is an important geodynamic process in this region. In this study we apply Earth models with 3D structure to determine if the inclusion of lateral structure can explain the poor performance of 1D models in this region. Three different approaches are used to construct 3D models of the Earth structure. For the first approach, we adopt an optimal 1D viscosity structure from previous work and add lateral variations based on four global seismic shear wave velocity anomalies and two global lithosphere thickness models. The results based on these models indicate that the addition of lateral structure significantly impacts modelled RSL changes, but the data-model fits are not improved. The global seismic models are limited in spatial resolution and so two other approaches were considered to produce higher resolution models of 3D structure: inserting a regional seismic model into two of the global seismic models and, explicitly incorporating regional structure of the Cascadia subduction zone and vicinity, i.e. the subducting slab, the overlying mantle wedge, and the plate boundary interface. The results associated with these higher resolution models do not reveal any clear improvement in satisfying the RSL observations, suggesting that our estimates of lateral structure are inaccurate and/or the data-model misfits are primarily due to limitations in the adopted ice-loading histories. The different realisations of 3D Earth structure gives useful insight to uncertainty associated with this aspect of the GIA model. Our results indicate that improving constraints on the deglacial history of the southwest sector of the Cordilleran ice sheet is an important step towards developing more accurate of GIA models for this region.

Comparison of 1D vs 3D viscosity models for glacial isostatic adjustment

2020 ◽  
Author(s):  
Paoline Prevost ◽  
Jeffrey Freymueller
Keyword(s):  
Finite Element ◽  
3D Structure ◽  
Earth Model ◽  
Earth Structure ◽  
Glacial Isostatic Adjustment ◽  
Element Analysis ◽  
Isostatic Adjustment ◽  
Viscosity Models ◽  
Test Region ◽  
Wide Range

<p><span>Accurate calculation of displacements due to glacial isostatic adjustment (GIA) are essential for studies of tectonics, sea level projection, and the estimation of recent ice melting or other mass transport. However, most GIA studies to date have used a 1D viscosity model, with earth parameters varying only in the radial direction, while surface geology and seismic tomography show that the thickness of the lithosphere and the structure of the mantle also varies laterally. Therefore, models with 3D earth structure are needed. Using a 3D earth model requires finite element models, which are computationally expensive and hence make it difficult to compute a wide range of potential parameter values. Consequently, the question is for which application is a 3D model necessary, and for which parameters (and where) do 1D models give sufficiently accurate predictions?</span></p><p> </p><p><span>In this study, we investigate the sensitivity of the GIA modeling to the earth structure, using the Abaqus finite element analysis software, an ice model assumed to be known, and various viscosity models. We start with Patagonia as a test region, because the 3D structure of the mantle is complex due to the proximity of the subduction of the Antarctic plate below South American and the Chile triple junction. In this region, the GIA contributes significantly to the regional recent rapid uplift.</span></p>

The impact of a 3-D Earth structure on glacial isostatic adjustment following the Little Ice Age in Southeast Alaska

2021 ◽  
Author(s):  
Celine Marsman ◽  
Wouter van der Wal ◽  
Riccardo Riva ◽  
Jeffrey Freymueller
Keyword(s):  
Upper Mantle ◽  
Little Ice Age ◽  
Seismic Velocity ◽  
Scaling Factor ◽  
Ice Age ◽  
Earth Structure ◽  
Glacial Isostatic Adjustment ◽  
Southeast Alaska ◽  
Isostatic Adjustment ◽  
Mantle Viscosity

<p>In Southeast Alaska, extreme uplift rates are primarily caused by glacial isostatic adjustment (GIA), as a result of ice load changes from the Little Ice Age to the present combined with a low viscosity asthenosphere. Current GIA models adopt a one-dimensional (1-D) stratified Earth structure. However, the actual (3-D) structure is more complex due to the presence of a subduction zone and the transition from a continental to an oceanic plate. A simplified 1-D Earth structure may not be an accurate representation in this region and therefore affect the GIA predictions. In this study we will investigate the effect of 3-D variations in the shallow upper mantle viscosity on GIA in Southeast Alaska. In addition, investigation of 3-D variations also gives new insight into the most suitable 1-D viscosity profile.</p><p>We test a number of models using the finite element software ABAQUS. We use shear wave tomography and mineral physics to constrain the shallow upper mantle viscosity structure. We investigate the contribution of thermal effects on seismic velocity anomalies in the upper mantle using an adjustable scaling factor, which determines what fraction of the seismic velocity variations are due to temperature changes, as opposed to non-thermal causes. We search for the combination of the scaling factor and background viscosity that best fits the GPS data. Results show that relatively small lateral variations improve the fit with a best fit background viscosity of 5.0×10<sup>19</sup> Pa s, resulting in viscosities at ~80 km depth that range from 1.8×10<sup>19</sup> to 4.5×10<sup>19</sup> Pa s.</p>

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