A network of Sonardyne instruments deployed by scientists from GEOMAR Helmholtz Centre for Ocean Research in Kiel for 15 months has measured underwater slippage of the southeast flank of Europe’s most active volcano, Mount Etna, for the first time.

GEOMar map

While satellite observations have previously shown that the flank of the volcano is slowly sliding towards the sea, until establishment of this network, it had been impossible to confirm if and how the submerged segment is moving. The results published in the international journal Science Advances confirm that the entire flank of the volcano is in gravity-driven motion and in one event the slope slipped about four centimetres in just eight days. The risk is that sudden and rapid failure of the entire slope could result in a catastrophic tsunami in the Mediterranean.

The network of five Sonardyne Autonomous Monitoring Transponders (AMTs) were deployed in April 2016, across the fault line that represents the boundary between the sliding flank and the stable slope, with three on the sliding sector and two on the presumed stable side of the fault line. The AMTs acoustically measure the distances between each other with a precision of less than one centimetre.

Geraint West, Global Business Manager – Ocean Science, Sonardyne Projects Manager Tom Bennetts and Chris Hammersley, Project Engineer – Navigation Systems, have all been directly involved in this project. They told us more:

Geraint West, “The AMT is a highly flexible instrument that has been used by research institutes around the world to measure seabed movements as diverse as rapid canyon turbidity flows to plate motion at deep subduction zones. This project is the first time that it has been used to measure the slippage of a volcano’s submerged flank.”

Tom Bennetts, “The AMT was originally developed to measure deformation of the seabed caused by the extraction of hydrocarbons over several years. We first deployed our AMTs on a large project over the Ormen Lange field in the Norwegian sector of the North Sea. For that project, some 220 individual instruments were deployed. The precision and endurance required for the Ormen Lange project showed us – and others – that our AMTs are also ideally suited for scientific studies of seabed. You could say that the rest is history.”

Chris Hammersley, “The Mount Etna project is one of several projects major AMT deployments I’ve been involved in, including a deployment of AMTs on the Nazca-South American Subduction Zone and the North Anatolian Fault (Sea of Marmara). Through these projects we’ve built up a close relationship with the scientists and engineers at GEOMAR, which means that we’re on standby to support them remotely when the AMTs are deployed and during routine data recovery missions. From our head office in the UK, we can support these projects remotely, 24/7. This means that we’ve been able to advise them on how best to optimally configure the instruments as well as troubleshoot any issues that arise, ensuring that GEOMAR use the valuable ship time on site to best effect.”

You can read more about the project here.