Volcanic Islands and Seamounts

Abstract

Recent advances in seafloor imagery systems have enabled the extensive mapping of submarine volcanic areas, depicting with unprecedented detail a large spectrum of landforms. They can be grouped in two main types: volcanic and erosive-depositional landforms, reflecting the interplay between constructive and destructive forces that control the growth and morphological evolution of volcanic edifices. Volcanic landforms mainly include primary volcanic constructs (cones, lava flows and delta, undifferentiated bedrock outcrops), but also volcano-tectonic features, such as caldera collapses. Erosive-depositional landforms typically cover most part of the volcanic flanks and include features related to wave erosion and sea-level fluctuations (insular shelves and guyots), gravity-driven instability processes (landslide scars), and density gravity flows (gullies, canyons, fan-shaped features, sediment waves). However, despite the large number of marine studies realized until now, we are still far from having a complete mapping of these areas as well as reliable models for the correct interpretation of several landforms, mainly because of the paucity of direct observations. A systematic monitoring of active processes is essential to understand the genesis and evolution of such phenomena; repeated multibeam surveys are playing a key role in this regard. Also the comparison and parameterization of these landforms in different settings can provide insights on the main factors controlling their genesis. But it is necessary to set shared and standardized protocols for the interpretation and analysis of morpho-bathymetric data, also in consideration of the exponential increase in data availability from these areas, whose study is becoming crucial for several disciplines.