Gas Flares of the Norwegian Arctic - Sources and distribution: A comprehensive mapping using MAREANO multibeam data

Gas flares from natural sources of hydrocarbon gases escaping through the seafloor to the water column is a phenomenon observed in many parts of the World’s Oceans. The occurrence of these acoustically and visually observed seepages have been recorded by using various sensors onboard different platforms. But the use of multibeam echosounder systems, with the capability of recording the whole water column acoustic backscattering, in recent years have given the opportunity to cover large areas in a short time span along with bathymetric mapping in a cost-effective way. Even though the data sizes are multiple orders of magnitude larger, the use of dedicated software’s and high-performance processing systems have given the opportunity to find acoustic anomalies resulting from the streaming of gas bubbles in water column.

The MAREANO programme which is aimed at mapping habitats through various methods has surveyed large areas of the Norwegian Arctic using multibeam systems. This has resulted in the acquisition of water column acoustic data covering a large area of Arctic Norway over in the last decade. These data have been interpreted and analysed together with other geological and ancillary data from other sensors such as photo/video observations, backscatter data, etc. leading us to relate these anomalies to various structural and geological formations. The database also gave us an opportunity to compare the differences between some of the multibeam systems in capturing these acoustic anomalies. More than approximately 5000 flares of varying magnitude and sizes were detected based on MAREANO water column data, in an area of about 139000 km². We present the results from these comprehensive surveys and discuss various possibilities that such a database can provide for present and future understanding in the development of Arctic.