Regional relative sea level (RSL) differs from the global mean due largely to Glacial Isostatic Adjustment (GIA), the ongoing deformation of the solid Earth to past land-ice changes. Modelling future GIA contributions to RSL requires knowledge of the evolution of ice extent since the Last Glacial Maximum (LGM, ~20,000 years before present) and rheology of the solid Earth. However, the contribution from solid-Earth deformation is poorly constrained. Understanding of mantle dynamics and its impact on solid Earth deformation can be improved through modelling of observations of the seismic cycle using a novel approach. Earthquakes induce significant stress change into the asthenosphere and provoke transient accelerated deformation. Studies of post-seismic deformation provide inference on the rheological structure of the mantle, which can improve GIA models. Recently, we formulated a new methodology to image the effective viscosity in Earth’s interior using surface deformation data as a linear inverse problem, which has yet to be tested at a global scale.
Here, we will reconstruct global-scale Earth deformation since the LGM using a global RSL compilation. Unlike instrumental constraints contaminated by other processes, RSL data predominantly record land-ice melting and the associated GIA response. Despite the importance, a global RSL compilation following a standardized approach does not exist. We propose bringing together sea-level researchers producing regional RSL compilations to create the first global synthesis. Through this project, we will be able to achieve:
- A global synthesis of sea-level data since the LGM.
- Inferring constraints on the rheological parameters of the lower crust and the asthenosphere.
- Inversion of GPS velocity field for strain and strain rate in the asthenosphere.
- Evaluation of the impact of lateral heterogeneity in the Earth model on GIA predictions.
- A global forward model of GIA since the LGM with lateral variations of mantle viscosity and lithospheric thickness.
- Earth Observatory of Singapore
- Ministry of Education, Singapore
2019 to 2022