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In this study the combined use of field mapping and measurements, remote sensing data analysis and GIS techniques for the geological mapping of KEA Island at a 1/50.000 scale, is presented. The geological formations, geotectonic units and the tectonic structure were recognized in situ and mapped. Interpretation of high resolution satellite images (Quickbird) and medium resolution satellite images (Landsat 7 ETM and ASTER) has been carried out in order to detect the linear or not structures of the study area. The in situ mapping was enhanced with data from the digital processing of the satellite data. Marine geology data such as bathymetric data and seismic profiles were also taken into account. All the analogical and digital data were imported in a geodata base specially designed for geological data. After the necessary topological control and corrections the data were unified and processed in order to create the final layout at 1/50.000 scale.

One of the newest satellite sensors with stereo collection capability is ALOS. ALOS has a panchromatic radiometer with 2.5m spatial resolution at nadir. According to the specifications its extracted data will provide a highly accurate digital surface model (DSM). Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) has three independent optical systems for viewing nadir, forward and backward producing a stereoscopic image along the satellite's track. Each telescope consists of three mirrors and several CCD detectors for push-broom scanning. The nadir-viewing telescope covers a width of 70km; forward and backward telescopes cover 35km each. Two ALOS data sets collected over the same area within a year were used. The same ground control points were used for the creation of the two DSMs. The two DSMs were compared to elevation data from different sources: 1/50.000 topographic maps and airphotos stereo-pair. The area of study is the broader area of Andritsena, Western Peloponnese, Greece. After a first control for random or systematic errors a statistical analysis was done. Points of known elevation have been used to estimate the accuracy of the DSMs. The elevation difference between the different DSMs was calculated. 2D RMSE, correlation and the percentile value were also computed and the results are presented.

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We examine the possible non-linear behaviour of potentially liquefiable layers at selected sites located within the expansion area of the town of Nafplion, East Peloponnese, Greece. Input motion is computed for three scenario earthquakes, selected on the basis of historical seismicity data, using a stochastic strong ground motion simulation technique, which takes into account the finite dimensions of the earthquake sources. Site-specific ground acceleration synthetics and soil profiles are then used to evaluate the liquefaction potential at the sites of interest. The activation scenario of the Iria fault, which is the closest one to Nafplion (<i>M</i>=6.4), is found to be the most hazardous in terms of liquefaction initiation. In this scenario almost all the examined sites exhibit liquefaction features at depths of 6–12 m. For scenario earthquakes at two more distant seismic sources (Epidaurus fault – <i>M</i>6.3; Xylokastro fault – <i>M</i>6.7) strong ground motion amplification phenomena by the shallow soft soil layer are expected to be observed

Earth systems are interrelated in complex ways, which are inadequately understood. An improved understanding of these systems is necessary in order to develop effective policies for hydrologie management. Furthermore, the results should be communicated to decision-makers. The aim of the work has been to evaluate the applicability of the use of digital multi-temporal Landsat 5 / 7 images and aerial photography, for the mapping of local scale fresh water outflows, geological features and monitoring changes of the water outflows in coastal areas. "Psahna" map sheet (HAGS, 1977) in the Central part of Evia island in Greece has been used as pilot project area of study. Processing techniques have been applied for the: • Application of integrated image processing / GIS vector data techniques. • Image integration and creation of data fusion image products. • Automatic raster to vector conversion techniques, for the identification of the areal extent of changes in conditions of the water outflows through time and final map updating. The contribution of the remotely sensed data to the geologic / géomorphologie mapping and identification of changes of fresh water outflow through time is indicated with the processed satellite imagery for the pilot project area. Generally, the use of the remotely sensed images in map updating lies in the fact, that various hydrologie and geologic features can be mapped quickly for large areas while any temporal changes can be identified and evaluated. The satellite data seem to be a cost-effective solution for the map updating procedure. The cost to processing functions is well justifiable to a geologic / hydro-geologic-hydrologic map updating procedure. The system provides monitoring and feedback at appropriate spatial scales, using high resolution satellite remote sensing data and state of the art GIS techniques. 931 http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 09/07/2020 03:21:28 |