Séminaire ISTeP - Tony Watts

(University of Oxford)

Submarine volcanism and the dynamics of the seafloor

One of the mysteries of the sea are the large number of seamounts that rise up on the seabed and, in a few cases, break surface to form oceanic islands. Volcanic in origin, seamounts are widely scattered throughout the world’s ocean basins, especially in the Pacific. Repeat swath bathymetric and ultra-long hydroacoustic data show that seamounts change their shape with time, sometimes dramatically. Seamounts are of geological interest because they record the absolute motions of Earth’s tectonic plates, the long-term strength of its rocky outermost layer, and the magmatic ‘pulse’ of its deep interior. They are also significant for earthquakes, especially at plate boundaries where seamount subduction influences forearc structure, seismicity patterns and slab geometry. Statistical studies suggest there maybe some 24,000 seamounts higher than 1 km that still remain to be discovered. The charting of these seamounts and the determination of their morphology, structure, and age remains one of many challenges facing marine geologists in the future.