Landslide Hazard Zonation in Greece

Abstract

Abstract. Landslide occurrences in Greece, covering a long time period were recorded and digitally stored using a relational database management system. The first evaluation of engineering geological data and the geographical distribution of the recorded cases led to the determination of most critical landslide prone geological formations, regarding lithology and structure and to a landslide hazard map compilation at a national scale. Keywords. Hazard zonation, database management, Greece IntroductionA systematic inventory of data concerning landslides and their quantitative expression in Greece, through a relational database management system, was firstly attempted at the end of 1980s by Koukis and Ziourkas (1991), following the general trends of similar studies in other countries. Furthermore, statistical analyses of the main factors affecting landslide phenomena and their interrelations were established by Koukis et al. (1994Koukis et al. ( , 1996Koukis et al. ( , 1997, based upon data recordings through the database of landslide movements covering the as above period of more than 45 years.In the last decade, the landslide activity is increasingly high as a result of increased urbanization and development (transportation routes, dams and reservoirs, industrial and urban activities) in landslide-prone areas, continued deforestation and extreme meteorological events. An increment of about 20% of the landslide occurrences has been recorded during the last five years all having serious socio-economic consequences resulted in a significant increase of total economic losses, fortunately without casualties.After those events, the authorities have focused their attention on mitigating the problem by avoiding the hazards or reducing the damage potential. To aid this planning the Department of Geology of Patras University and the Institute of Geology and Mineral Exploration (IGME) were commissioned to undertake an extensive study regarding landslide hazard zonation. The techniques used were in accordance with the required national and regional scale of zonation of extensive areas according to their susceptibility to slope instability phenomena and they mainly included: (a) detailed inventory of slope instability processes and their study in relation to engineering geological setting, (b) analyses of causing and triggering factors and (c) spatial distribution of these factors.The aim of this paper is to evaluate some first considerations regarding the influence of the geological conditions on landslide frequency distribution in the Greek territory using simple statistics and direct mapping methodology for landslide hazard zonation. Geological Setting and Landslide PhenomenaIn Greece, which has been experienced a complicated history of geophysical development during the Alpine orogenic cycle, several geotectonic zones or regions can be distinguished by fundamental differences both in lithology and structure (Figs. 37.1 and 37.2). The elongation of those zones more or less coincides with the trend of the main mountain ran...

Rock Slope Stability Problems in Natural Sightseeing Areas - An Example From Arvanitia, Nafplio, Greece

“…Unfortunately, the ignorance of the engineering geological characteristics and the underestimation of the stability problems led to the inappropriate land planning design of many other natural sightseeing areas all over Greece (Rozos & Nikolaou, 1996;Koukis et al 1997;Koukis & Rozos, 1997;Koukis et al, 2005;Loupasakis & Karfakis, 2007). Figure 8 presents as an example, the sightseeing site of Kastoria lake walkway exhibiting similar geotechnical problems.…”

Kinematic Analysis Evolution of Extended Landslides: Two Case Studies From Western Greece

“…Generally, the presence of highly tectonic and sheared -weathered formations of Alpine basement (flysch) in that area were resulted in periodically instability phenomena, triggered by heavy rainfall and seismic activity Koukis et al, 2005Koukis et al, , 2009. On 25-26 April and 3 May 1971 large scale failures were recorded, (Andronopoulos, 1982).…”

Exploring the Impact of Analysis Scale on Landslide Susceptibility Modeling: Empirical Assessment in Northern Peloponnese, Greece

“…Greece can be characterized as a region highly prone and vulnerable to the occurrence of landslides [4]. Due to (a) uncontrolled or not well planned development by ignoring the engineering geological and geotechnical conditions, (b) excessive rainfall events generating high pore water pressure, and (c) strong earthquakes resulting in ground shaking, more and more areas of the country are affected by them [5,6].…”