“Talks on GIA” seminar – Constraining GIA where the mantle is heterogeneous AND Community Priorities for GNSS Measurements

We will have two presentations.

• Erica Lucas (University of California, Santa Cruz, USA) will present “Constraining Glacial Isostatic Adjustment where the mantle is heterogeneous”.
• Terry Wilson (Ohio State University, Columbus, USA) will present “Community Priorities for GNSS Measurements to Constrain GIA – Results of a Survey”

“Constraining Glacial Isostatic Adjustment where the mantle is heterogeneous”
To date, investigations of the impact of 3-D Earth structure on GIA have adopted solid Earth viscoelastic models based on global- and continental-scale seismic imaging, with variability at spatial length scales >150 km. However, regional body-wave tomography shows mantle structure variability at smaller length scales (∼50–100 km) in central West Antarctica. We investigate the effects of incorporating smaller-scale lateral variability in upper-mantle viscosity into 3-D GIA simulations, finding that upper-mantle structure at the glacial drainage basin scale is found to impact GIA model predictions for modern and projected ice mass changes. Differences between simulations adopting upper-mantle viscosity structure inferred from regional- versus coarser continental-scale seismic imaging are large enough to impact the interpretation of crustal motion observations from GNSS and reach up to ∼15 % of the total predicted sea level change during the instrumental record.

“Community Priorities for GNSS Measurements to Constrain GIA – Results of a Survey”
A survey in 2025 revealed community views on the most pressing science questions in Antarctica that can be addressed using GNSS measurements and on the regions in Antarctica where in situ GNSS observations will be most helpful in answering these science questions. A summary of survey results will be presented for discussion.