Fig. 1

Schematic illustration of GNSS-A seafloor positioning using a slackly moored buoy system. The buoy is moored with an anchor (approximately 6 tons) using a sufficiently longer rope (4700 m) than the depth (3000 m) near the center of the PXP array, which consists of six PXPs aligned in a triangle. A sequence of GNSS-A observations is carried out automatically at preset intervals (11 shots/week) or on demand from a land-based station. At the end of a measurement sequence, the data are transmitted to the land-based station via Iridium satellite communication