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The Italian continental margins are part of the tectonically-active and complex Central Mediterranean area and are experiencing a very rapid geomorphic evolution. Geologic processes ranging from volcanic activity to active faulting and slope instability are frequent along the Italian margins and result in areas of potential geohazard relative to human settlements and activities. The exploitation of geohazard-related features that are detectable at the seafloor is therefore one of the main issues in the field of Marine Geology.
MaGIC project (Marine Geohazards along the Italian Coasts), a 5-year initiative funded by the National Civil Protection Department, is the most relevant contribute of the Italian Scientific Community in the field of marine geohazard mapping and monitoring. The project aims at producing a swath bathymetry database and compiling maps (scale 1:50.000) of geohazard-related features in the shelf and slope of most of the Italian margins.
In recent time, sea floor detection through extensive multibeam investigation has led to a growing attention on the role of small-scale but frequent instability. Data that are being collected within MaGIC indicate that small-scale slide scars and deposits are very frequent on the Italian margins and display two main distributional patterns: 1) one in which sediment failure is pervasive and affects the continental margin on a regional scale; 2) one in which failure concentrates within submarine canyon heads indenting the continental shelf. In this latter case, retrogressive erosion of the canyon head is enhanced and the process by which canyon erosion progressively cannibalizes the shelf results significantly accelerated. As a consequence, canyon heads are very close to the coastal area where anthropogenic infrastructures are present. The process may be particularly rapid in areas where the continental shelf rims steep/deep tectonically-controlled basins and is therefore very narrow.
Phenomena from southern Italy (Calabria) will be presented, where the shelf margin is only few hundred metres from the coast and canyon heads deeply incise the slope, undermining harbours and other infrastructures. Here, small scale, periodic mass failure within the canyons has relevant impact for the coastal zones and for the risk related to human impact as a factor that may amplify or induce catastrophic phenomena.
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