Data Acquisition and Mapping for Geohazard Analysis

The aim of the current work is to introduce bathymetry data into Geographic Information Systems tools for mapping, monitoring and assessing the geohazards in the Greek islands between Crete and Kasos at the Mediterranean sea. The offshore area lying east of Crete is studied on the basis of new bathymetric data. The data was obtained by a multibeam sonar system which allows the imaging of the seafloor. The collected multibeam data have been extensively processed in order to be cleaned of erroneous beams, filtered of noise, processed of navigation data and interpolated of missing beams. The analysis and representation was performed with the ArcGIS software. Resulting maps were analyzed and presented. The analysis of the slope values and the watershed at the eastern part of Crete reflects intense tectonic activity. We have found out that the basin geometry is an elongated rectangular which is divided into seven sub-basins. The multibeam bathymetric data show that the relief is a complex compound of submarine canyons, landslides and a well-defined slump with vertical displacement. These conditions increase substantially the potential of a geohazard in the area.