A new breed of underwater sensor that is able to self-calibrate, enabling precise, long-duration subsidence monitoring at all depths, has been deployed at scale for the first time. The 20-plus Fetch Ambient-Zero-Ambient (AZA) pressure monitoring transponders (PMTs), developed by Sonardyne, will support an ongoing long-term, large-scale seabed monitoring project at Ormen Lange–Norway’s second largest gas field–for A/S Norske Shell. Unlike