Glacial isostatic adjustment (GIA) is an ongoing phenomenon that characterizes the landscape of the High Coast (63°04'N, 18°22'E, Sweden) / Kvarken archipelago (63°16'N, 21°10'E, Finland) UNESCO World Heritage site. GIA occurs as the Earth's crust that was depressed by the continental ice sheet during the last glacial period is slowly rebounding towards isostatic equilibrium. The maximum rate of land uplift in the area is more than eight millimetres per year, whichalong with the very different topographical reliefs of the opposite coastsmakes the region an excellent study area for land uplift as a phenomenon. As there is a marine area between the coasts, shore displacement is an essential part of the phenomenon in the study area.The cartographic representation of GIA and shore displacement has classically relied on static maps representing isobases of the uplift rates and of ancient shorelines. However, to dynamically visualize and communicate the continuity and the nature of the phenomena, an animated map is required. To create a visually balanced, seamless animation, we need to create high-resolution image frames that represent digital elevation models (DEMs) together with extracted shorelines of different moments of time. To create these frames, we developed a mathematical model to transform the DEM in a given time for the past ~9300 years. We used the most recent LiDAR-derived DEMs of Finland and Sweden, and a bathymetric model of the Gulf of Bothnia as our initial data, along with a land uplift rate surface derived from geophysical measurements. We compared the current uplift rates with the shoreline observations of the ancient Baltic Sea stages, Litorina Sea and Ancylus Lake, and created a linear model between the elevations of the shorelines and the present-day uplift rates, as there was a near-linear correlation in both cases. Based on the current uplift rates and the elevations and the dating of the ancient shorelines, we derived an exponential model to describe the non-linear correlation between the elapsed time and the occurred land uplift. Near the present time, we adapted the formula proposed by Ekman (2001) to make the model more robust closer to the present day.We assumed that although the uplift rate varies in time, the spatial relation of uplift rates remains the same. Furthermore, as the land uplift is an exponentially decelerating phenomenon occurring with a significantly lower annual rate than shortly after the de-glaciation (Eronen et al. 2001, Nordman et al. 2015, and with most of the total uplift already having occurred (Ekman 1991), we assumed a constant rate of uplift from the present day to the near geological future. We did not consider potential sea level changes caused by human-driven climate change in the predictions, as the geological time scale vastly exceeds the time range of the climate models. Neither did we take into account the historical transgression phases, as they did not appear dominating in the area.The elevation and bathymetry data were harmonized and resampled into 4K ...
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