Imaging of a giant rifting volcano near Bouvet Island

What is it about?

Spiess Ridge is the most westerly spreading segment of the Southwest Indian Ridge and lies adjacent to the Bouvet Triple Junction. The ridge was imaged with a reconnassance seabed mapping system (Hawaii-MR1), which recorded acoustic backscattering intensity (useful to identify areas of highly backscattering bedrock contrasting with weakly backscattering sediment) and a form of bathymetry from phase differences between recording transducers. The data revealed that large areas of Spiess Ridge are highly backscattering, suggesting the presence of widespread young lava flows. The extent of volcanism, reaching 30 km in the south of the ridge, was also evaluated using magnetic anomaly profiles, which show an unusually broad axial anomaly.

Featured Image