Measurement of relative position of Halley VI modules (MORPH): GPS monitoring of building deformation in dynamic regions

The Halley VI Antarctic Research station was designed as a series of linked, ski-mounted modules. This makes it possible to relocate the station in the event that changing Antarctic conditions require it. These modules are gradually moving relative to each other, distorting the station configuration and potentially threatening the inter-module connections. In this paper we describe a scalable network of GPS receivers used to monitor this distortion. This network has been installed and operational for two months, and is measuring the relative motion of the modules to an accuracy of 1 mm, despite the station and its underlying ice shelf moving metres each day under the influence of ocean tides and glacial flow.