Focal mechanism parameters of earthquakes with magnitude M_w>5.0 and shallow focal depth (h <40 Km) from Greece and its surroundings have been estimated using the technique of far-field body waveform modeling. We inverted P- and SH- waveforms recorded at stations of the Global Seismograph Network (GSN), with epicentral distances 30^o<Δ<90^o, using a point source approximation. First motion polarities of P- waveforms recorded at lower epicentral distances were complementary used in order to better constrain the focal mechanisms.

The analysis of these data, combined with the fault plane solutions of 107 earthquakes taken from the literature, can be summarized as follows:

·        Low angle thrust faults dipping to the NE dominate along the coasts of Albania and NW Greece.

·        The southwestern part of the Hellenic arc is characterized by low angle thrust faulting, in some cases combined with a significant strike slip motion, and reverse faults as well.

·         The fault plane solutions of 6 earthquakes (M_w>5.4) that occurred in western Peloponnese show strike-slip motion along nearly vertical fault planes.

·        The widespread strike-slip motion observed in the northern Aegean Sea, which is due to the splay of the North Anatolian Fault into several strands as it enters the Aegean, extends to the south up to the N38^o parallel.

·        East-west extension dominates along a narrow zone following the Dinarides-Hellenides mountain belt up to the Rhodes Island in the eastern Hellenic Arc, while continental Greece and southwestern Turkey are characterized by normal faulting along ~E-W trending planes.

(Source: evmolpos.gr)

The central area of the Ionian Islands is dominated by the existence of a major tectonic structure called the Cephalonia Transform Fault (CTF). Its main part (Cephalonia segment) has been identified by previous work based on the spatial distribution of earthquake foci, fault plane solutions of strong earthquakes, active tectonics, structural studies and geodetic measurements. This part (Cephalonia segment) which exhibits strike-slip motion with a thrust component, strikes in a NE direction, dips SE and has a length of ~90 km. In the present paper information concerning new fault plane solutions, orientation of isoseismals, sea bottom topography and recent GPS results are used to further check the properties of this southern part of the CTF and to explore its northeastward prolongation to Lefkada island. It is shown that the CTF is extended to the western coast of Lefkada. This northern branch (Lefkada segment) of the CTF which is also characterized by strike-slip motion with a thrust component, strikes in a NNE direction, dips to ESE and has a length of ~40 km. These two segments of the CTF form a major kinematic boundary where the slip rate is 2-3 cm/yr.

(Source: evmolpos.gr)

Geographical data services, via internet, require proper management of spatial and non-spatial data. GIS helps in effective analysis and management of spatial data. Spatial data attributes can be efficiently managed using open source based Object Oriented Relational Database Management System (RDBMS). Target of this project was the development of a Web-based system by integrating the Mapserver (UMN), PHP, Apache Web Server, Openlayers, PostGIS and PostgreSQL Object-Relational data-base by adopting a Web based client/server environment. The final system provides a web-based platform for Land expropriation’s procedures in Greece and their implementation at the construction of public works and land management in open pit mining. The end users are specialists, planning agencies, citizens, engineers and private entities. To access the spatial data by the user, a Web browser and Intranet or Internet only, is needed.

(Source: evmolpos.gr)

This project describes a workflow for the DEM extraction from unrectified satellite stereo scenes, its visualization and integration in GIS environment. The results obtained using a stereo scene acquired by Ikonos Imagery over Central Macedonia – North Greece are presented and commented. The images are oriented with a rigorous photogrammetric model for CCD linear array sensors. The model estimates the sensor internal and external orientation with least squares adjustment, using a suitable number of ground control points. For the DEM generation, the points are automatically extracted in the images at sub-pixel accuracy with a least squares matching algorithm and their 3D coordinates are then calculated with forward intersection using the external and internal parameters estimated during the image orientation. The produced terrain model is used for further environmental investigations.

(Source: evmolpos.gr)

During the last years it has become a common knowledge that urban development is a complicated dynamic process, which involves various physical, social and economical factors. However, this process can be controlled during the design stage of new urban areas so that human activities and environment will coexist in a friendly way. In order to achieve this goal the urban planners need to know which factors should affect the urban growth and how these factors are spatially correlating each other.

This paper applies a Multi-Criteria analysis method on a Geographical Information System (GIS) basis in order to determine which areas are most suitable for urban growth based on environmental, geological and land-use criteria. This work was performed during the Urban Planning Study of the Municipality of Kalamata, located in SW Greece.

(Source: evmolpos,gr)

Flooded area and flood hazard assessment in Gallikos catchment area (North Greece) were evaluated using remote sensing (RS) data with the geographical information system (GIS). Image data from the Landsat ETM + were used to analyse historical flood events, which sets a hundred-year record for the inundated areas, with severe damage occurring throughout this region. In order to estimate the flooded area accurately, the images taken during the flood and dry season which were classified into water and non-water categories were superimposed. A new flood hazard map, created from the land cover category and elevation height data which were ranked by flood affected frequency, can be used to evaluate flood risk using only RS data and elevation height data.

(Source: evmolpos.gr)

Ground subsidence due to overexploitation of the aquifers has posed a constant threat to the safety of surface infrastructure such as motorways, railways, power lines, and telecommunications cables. Traditional monitoring techniques like using levels, total stations and GPS can only measure on a point-by-point basis and hence are costly and time-consuming. Differential interferometric synthetic aperture radar (DINSAR) together with GPS and GIS have been studied as a complementary alternative by exploiting multi-source satellite SAR images over an urban area southeast of Thessaloniki. Digital elevation models (DEMs) derived from ERS-1 and ERS-2 tandem images, photogrammetry, airborne laser scanning, and the Shuttle Radar Topography Mission were assessed based on ground survey data using levelling as well as GPS-RTK. The identified high quality DEM was then used in the DINSAR analysis. 

(Source: evmolpos.gr)

The main problems in watershed management are deforestation and the expansion of agricultural land, which together cause soil erosion and nutrient depletion. Satellite Remote Sensing (RS) and Geographic Information Systems (GIS) are useful tools for watershed management and monitoring. RS data have been found to provide timely and reliable information for monitoring forest resources and agricultural crops, as long as they are supported by ground data. Obtaining the same information by field surveys would take a long time and considerable human resources. RS data allows us to see changes in the spatial distribution of various land resources, which is otherwise difficult to keep updated on a national scale. This involved interpretation from digital orthophotos as well as digital image processing of high resolution satellite data, namely SPOT, Landsat TM and World View II data. Extensive use of the digital terrain model was made for analyzing the complex watershed terrain. And based on the Universal Soil Loss Equation with revised topographic factor, a spatial and temporal analysis of soil erosion was made. This information was then used for developing a sustainable land use plan by considering the soil erosion as the limiting factor for sustainability.

(Source: evmolpos.gr)