COMPILATION OF A UNIFIED AND HOMOGENEOUS AEROMAGNETIC MAP OF THE GREEK MAINLAND

We present a unified and homogeneous digital aeromagnetic map of the Hellenic mainland, based on the 1:50,000 map series of IGME. These maps cover the areas A1, A2, B, C1, C2, C3, D1 compiled by Hunting Geology and Geophysics Ltd. and measured at nominal ground clearances (flight altitudes) 150m AGL, 150m AGL, 300m AGL, and 2300m AMSL respectively (part of C2 with 3000m AMSL). We also include the entire area of Northern Greece, measured by ABEM AB with nominal ground clearance 275±75m AGL. The original map sheets were digitally imaged, georeferenced, digitized along contour lines and interpolated onto regular 250´250m grids. The unified aeromagnetic map was constructed by collating the mosaic of the resulting gridded data. Using upward/ downward continuation techniques various homogeneous versions of the map, were compiled by referencing of the observed mosaic total magnetic field to a unique constant ground clearance or to a unique constant elevation above mean sea level. This is the first time there is a complete and unified image of the magnetic signature of the isopic zones and rock formations comprising the Hellenic mainland, with particular reference to the ophiolite suites, which provides additional insight into the Alpine and post-alpine tectonics of the area

Ground Movement Characteristics above Mined Panels in Appalachia-an Empirical Approach

The growing recognition of mining subsidence and its effects has provoked numerous investigations into the modeling and prediction of this phenomenon. Through an analysis of case histories and examination of the various modeling techniques, it has become apparent that empirical studies currently represent the most realistic approach to this problem. However, the collection, analysis and interpretation of subsidence and strain data acquired from case studies presents substantial difficulties, due to varying monitoring techniques and methods of analysis. In this paper it is suggested that a prescribed monitoring program could eliminate these problems and ensure quality data by standardizing the measurement process. Such an effort may also increase the number of case studies available for analysis, allowing more intense investigations of subsidence prediction methods. Finally, some basic subsidence relationships developed from the established subsidence data bank on longwall and room and pillar mines in Appalachia are discussed in detail. These relationships may provide important information on the characteristics of ground movements above mined areas and thus greatly facilitate engineering design under these conditions

Prediction and evaluation of nonlinear site response with potentially liquefiable layers in the area of Nafplion (Peloponnesus, Greece) for a repeat of historical earthquakes

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

Europe as a multilevel federation

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INVESTIGATION PROCESSES AT THE KATO SOULI BASIN

This work presents the results of gravity, TEM and geological surveys conducted in the area of Kato Souli (Greece), as Study of its hydrogeological characteristics and mapping through GIS. The gravity survey offered a rather detailed image of the alpine basement and together with surface geological observations, insight into the post-alpine tectonic processes that have controlled the development of the area. The TEM Survey produced detailed three-dimensional images of the aquifer systems and salination conditions. The results have shown that (a) the alpine basement is located Much deeper than previously thought and, (b) that the sea water intrusion takes place both near sea level and at depth. The depth and morphology of the alpine basement are believed to have been fashioned by faults that either have not been active during the Quaternary, or are buried under thick terrestrial and alluvial deposits. Sea water intrusion forms at least two distinct salination horizons, presumably as a result of intersecting faulting structures that facilitate horizontal and vertical transportation of sea water between permeable formations. The vertical alternation of permeable-impermeable rock formations may be attributed to (alpine) folding, which results in vertical repetition of the same lithological units, in this case karstified marbles