Mid-Holocene ice history inferred from GIA-induced crustal motion around Lützow-Holm Bay, East Antarctica

The history of ice melting and the viscoelastic properties of the mantle heavily influence Antarctic crustal deformation caused by Glacial Isostatic Adjustment (GIA). The interaction between ice history and mantle viscosity further complicates the complex Antarctic GIA. Nonetheless, geodetic observations, such as GNSS, are crucial for constraints on the GIA model parameters.

For over two decades, the Japanese Antarctic Research Expedition (JARE) has been using GNSS and absolute gravity measurements to obtain data along the coast of Lützow-Holm Bay, primarily at Syowa Station. This study examines the geodetic signals associated with GIA from observations along the Lützow-Holm Bay coastline in East Antarctica, and we also conduct GIA simulations based on the recent report of rapid ice thinning in the target region during the mid-Holocene.

Based on geomorphological surveys and surface exposure ages, Kawamata et al. (2020: QSR) showed that the region experienced rapid ice thinning of over 400 m from about 9 to 6 ka. Representative deglaciation models, such as ICE-6G, do not account for this rapid thinning process. Therefore, we investigate the variability of the geodetic signals using the ice history, including this rapid thinning. Our predictions demonstrate that incorporating the modified ice history results in consistent outcomes with the observations. This finding supports the notion that rapid ice melting occurred in the Holocene and suggests that geodetic observations can help constrain this region's ice sheet melting process. Additionally, we will present a possibility of the readvance following the rapid retreat based on the precise GIA modelling.