Scientific investigations of the glacial isostatic adjustment (GIA) started in the early 18th century in Fennoscandia, and since then various data have been collected, e.g. relative sea-level (RSL), tide gauges records, leveling, GPS, absolute and relative gravity measurements, and nowadays also data from satellite missions. With the help of these data investigations regarding the mantle structure have been made in Fennoscandia, North America and a few other regions in the world.

However, there are still remarkable differences in the resolved properties of the mantle, especially in Fennoscandia. Early results, for example, include a 100 km thick low viscosity asthenosphere with 1.3×10**19 Pa s (van Bemmelen and Berlage, 1935), a 200 km thick asthenosphere with 10**20 Pa s (McConnell, 1968), a 75 km thick asthenosphere with 4 × 10**19 Pa s (Cathles, 1975), and a 100 km thick asthenosphere with 1.2×10**19 Pa s (Wolf, 1987). GIA modeling has undergone a huge improvement since its beginning. Nowadays with the computational power, 3D spherical models based on different techniques are mainly in use. They include the theoretical basics such as sea-level equation, earth rotation and, partly, self gravitation.

Appropriate regional models also exist, which may allow the inclusion of crustal structures such as sedimentary basins and faults for selected special investigations such as post-glacial-induced earthquakes. The Earth structure beneath Fennoscandia seems now to be generally characterized by a laterally varying lithosphere with a thick root of more than 200 km in central-east Fennoscandia, then becoming thinner to the outer parts. South-west Sweden is expected to have about 100 km, the German North Sea coast as well as the Norwegian Atlantic coast about 80 km. A low-viscosity asthenosphere underneath the elastic lithosphere is still under debate. The upper-mantle viscosity can be bracketed between 10**20 and 10**21 Pa s, whereas the latest results calculated from different data yield between (3–8)×10**20 Pa s. The viscosity is getting higher towards the lower mantle.

In this session we invite papers, which are focused on determination of the mantle viscosity from post-glacial rebound and its importance and impact on GIA phenoma around the world.

Invited speaker: Larry Cathles (Cornell University)