Seafloor mapping for geohazard assessment: state of the art

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EDITORIAL

Seafloor mapping for geohazard assessment: state of the art Francesco L. Chiocci • Antonio Cattaneo Roger Urgeles



Published online: 29 May 2011 Ó Springer Science+Business Media B.V. 2011

Abstract During the last two decades, increasing use of full-coverage sonic mapping of the seafloor has made us more aware of the large and different number of seafloor processes and events bearing significant geohazard potential. This awareness combines with the increasing use of the seafloor for infrastructure and with the high density of population and settlement on the coast. Seafloor mapping is the first step in making a census of the geohazard-bearing features present in a given offshore area. It often provides the only tool for a comprehensive, although non-specific, seafloor geohazard assessment over large areas that are scarcely groundtruthed by acoustic prospection and seafloor sampling. However, the characterization of geohazard features on a morphological basis alone is limited, and more detailed investigations are needed to define the character and state of activity of potentially hazardous features. Such investigations include the use of deep-tow or autonomous platforms designed to acquire high-resolution data at depth as well as in situ measurements, both being very expensive activities not applicable over large areas. Thus seafloor mapping is often not only the first and the main but also the only tool for a comprehensive seafloor geohazard assessment. This special issue represents an example of the diversity of approaches to seafloor geohazard assessment and

F. L. Chiocci (&) Dip. Scienze della Terra, Universita` di Roma ‘‘La Sapienza’’, National Research Council, CNR-IGAG, Rome, Italy e-mail: [email protected] A. Cattaneo Ifremer, GM-LES, BP70, 29280 Plouzane´, France R. Urgeles Institut de Cie`ncies del Mar (CSIC), Barcelona, Spain

summarizes the present state of this discipline. Both the diverse technologies applied and the specific aims of offshore geohazard assessment brought different communities to deal with the study of seafloor processes and events from remarkably distinct viewpoints. We identified three end members in offshore geohazard assessment: (1) geohazard assessment ‘‘sensu stricto’’, (2) ‘‘engineering’’ geohazard assessment, (3) ‘‘non-specific’’ geohazard assessment. These are being conducted by industry, academia and public agencies in charge of civil protection and land-use planning and management. Understanding the needs and geohazard perception of the different groups is a necessary step for a profitable collaboration in such an interesting and rapidly developing field of marine geology. Keywords Geological risks  Multibeam bathymetry  Natural hazards  Seafloor morphology  Submarine landslides

Introduction In May 2009, an international conference on ‘‘Seafloor Mapping for Geohazard Assessment’’ was held in the charming location of the Giardini ‘‘La Mortella’’ in the volcanic island of Ischia (Naples Gulf, Italy) within the umbrella of the IGCP project 511 and