Nikolaos Sabatakakis

• Professor
• Professor at University of Patras

Greece is a country particularly covered by limestone formations that offer natural beauty due to the karstic phenomena. However, depending on the slopes' geological and geometrical characteristics they could pose in danger to infrastructures and human activities. In the framework of this study, the three prevailing limestone rock masses (Pantokrat...

This research aims to investigate the rockfall kinetics and particularly the individual parameters affecting rockfall's kinetic energy, with a more meticulous analysis of the restitution coefficients (vertical R N and tangential R T). For this purpose, a mathematical model was developed using Matlab software, based on the kinematic analysis of rock...

Three of the most well-known historical landslide areas in Western Greece were examined, concerning their temporal and kinematic evolution. Long-term ground displacements based on inclinometer data were analyzed. The aim of this study is to estimate the velocity trend type of movement through the years. The total time frame of kinematic evolution r...

This research focuses on accessing the suitability of specific igneous rocks for their potential use as aggregates in road pavement layers. During the current research, several quality control tests were carried out on andesite and dacite rocks, obtained from the areas of Methana and Agioi Theodoroi, approximately 60 Km West of Athens, Greece. The...

Η συμπεριφορά του έντονα αποδομημένου και αποσαθρωμένου φλύσχη διερευνάται μέσω εργαστηριακής προσέγγισης στη συσκευή διάτμησης μεγάλων διαστάσεων σε εδαφικά δείγματα, προερχόμενα είτε από δειγματοληπτικές γεωτρήσεις, είτε από επιφανειακές εμφανίσεις του φλύσχη σε χαρακτηριστικές περιοχές-ζώνες εκτεταμένων κατολισθήσεων. Οι συνθήκες εκτέλεσης των δ...

The study aims to present quantitative-based landslide susceptibility mapping through different procedures. Medium- to small-scale analysis was performed applying the most common statistical methods used for this purpose. For that reason, a complete landslide inventory is also presented consisting of about 209 events from 1913 to 2015 in a selected...

In Western Greece, rockfalls occur every year in residential areas and on public roads, causing considerable societal and economic damage. As a result, rockfall hazard assessment is a necessity and can be a very important tool for scientists, planners, decision makers, and local authorities. In the current study, a GIS-based rockfall hazard assessm...

It's widely known that the procedures of soil erosion are affected by a number of physical and human factors and are appeared with different intensities in different places. However, the spatial and temporal scales of these procedures are still poorly understood. Therefore, the control and prediction of soil erosion and deposition are a complex and...

This study presents the synergy of multidisciplinary surveys for the monitoring of an active landslide in Western Greece. The aim of this paper is to highlight and validate a methodology based on multiple sensors data integration which can successfully be used to manage natural disasters or to improve the knowledge of a specific phenomenon in order...

A series of laboratory tests was conducted on selected intact sedimentary (sandstones and limestones) and igneous (granites and andesites-dacites) rocks obtained from several sites of Greece. Physical and mechanical properties were determined, while the investigation was focused on strength parameters determination and especially on Hoek-Brown stre...

A digital engineering-geological map of the Athens Prefecture area was compiled at an original scale of 1:10.000 by IGME in cooperation with Engineering Geology Laboratory of Patras University. The map is related to a database management system constructed according to the project’s special needs, including geotechnical and geological data mainly o...

The aim of this paper is to determine the elastic parameters of some rocks and especially limestones, schist, sandstones, conglomerates, peridotites and granites using a large number of laboratory tests performed on intact rock samples. The range of values for Young`s modulus and uniaxial compressive strength is evaluated, while the relationship be...

The use of GIS for various types of data is considered to be of high importance, mainly because it is bringing together information from multiple sources. In addition, the new Internet technologies and applications of global world maps, like Google Maps, give the opportunity to build systems that the geographical information can be recorded and adm...

Interferometry constitutes a technique of acquisition height information with a range of applications, such as Digital Surface Model (DSM) generation in order to monitoring the Earth's surface. This work is focused on interferometric DSM creation utilizing radar data of Sentinel-1 and TerraSAR-X missions, covering the wider area of Northern Pelopon...

A multipurpose engineering geological map of a natural heritage site including inland and offshore areas has been compiled to provide information on many aspects for land use optimization, sustainable development and environmental protection. The mapping approach was based on data provided by conventional onland field works, marine remote sensing s...

Two of the most well known historical landslide occurrences are analyzed and their temporal evolution is presented. The sites of Panagopoula and Karya are often referred as the most representative cases of long term ground displacements based on inclinometer monitoring data. Regarding these cases, the heavy rainfalls constitute the main controlling...

The current paper presents the combined use of geological-geotechnical in situ data, remote sensing data and GIS techniques for the evaluation of a subsurface geological model. High-accuracy Digital Surface Model (DSM), air photos mosaic and satellite data, with a spatial resolution of 0.5m were used for an orthophoto base map compilation of the st...

The earthquake‐induced landslide hazard in Greece is evaluated by means of a parametric time probabilistic approach. First, by taking into account the characteristics of seismicity affecting Greece, we calculated occurrence probabilities for different levels of seismic shaking expressed in terms of Arias intensity for a time interval of 50 yrs. The...

An active landslide can be monitored using many different methods: Classical geotechnical measurements like inclinometer, topographical survey measurements with total stations or GPS and photogrammetric techniques using airphotos or high resolution satellite images. As the cost of the aerial photo campaign and the acquisition of very high resolutio...

In August 2007, western Greece suffered one of the most devastating wildfires that has ever happened on a European level. During the 4-year period post-fire, a series of shallow landslides triggered by rainfall occurred in fire-affected areas mainly covered by Neogene sediments (marls and sandstones), causing severe economic damage. Relationships b...

In this paper a specific example of the synergistic use of geotechnical survey, remote sensing data and GIS for rockfall risk evaluation is presented. The study area is located in Western Greece. Extensive rockfalls have been recorded along Patras - Ioannina highway just after the cable-stayed bridge of Rio-Antirrio, at Klokova site. The rockfalls...

Some typical landslide phenomena in western Greece, in terms of the geological composition and structure of the affected materials, induced by heavy rainfalls are thoroughly studied and analyzed. The studied cases involved composite landslides on flysch and Neogene weak rock materials that constitute the most critical landslide prone geological for...

In this study eight commercial available fusion techniques and more especially the Ehlers, High Pass Filter, HCS (Hyperspherical Color Space), Modified IHS (ModIHS), Pansharp, Pansharp2, PCA, and Wavelet were used for the fusion of a Declassified KH-7 airphoto and a Landsat1 MSS image. Both images were acquired on 1972. The panchromatic data have a...

Western Greece is suffering by landslides. The term landslide includes a wide range of ground movement, such as slides, falls, flows etc. mainly based on gravity with the aid of many conditioning and triggering factors. Landslides provoke enormous changes to the natural and artificial relief. The annual cost of repairing the damage amounts to milli...

In this paper, restitution coefficients for various slope surfaces are proposed as obtained from back-analyses calculations that have been carried out in several sites in Western Greece affected by extensive rockfalls. These occurrences have been thoroughly studied in order to investigate the extent of the events, assess the hazard and propose prot...

Landslide phenomena constitute a major geological hazard in Greece and especially in the western part of the country as a result of anthropogenic activities, growing urbanization and uncontrolled land – use. More frequent triggering events and increased susceptibility of the ground surface to instabilities as consequence of climate change impacts (...

Sandstone intact rock specimens are tested to study their point loading strength, while the microscopic properties of the tested specimens are analyzed in thin sections to determine the mineral composition, grain size, cement and contact modes between grains. The intrinsic influence of petrographic characteristics on measured strength is evaluated...

The objective of this study is to perform a preliminary national-scale assessment of the landslide susceptibility in Greece using a landslide inventory derived from historical archives. The effects of controlling factors on landslide susceptibility combined with multivariate statistics have been evaluated using GIS aided mapping techniques. Thousan...

Shear wave velocity is an important input parameter for dynamic ground analysis. Standard penetration test blow counts, static cone penetration tip resistance and shear wave velocity (VS) obtained by the cross-hole technique have been collected from a large number of projects in Greece over the last 10years and regression analysis used to develop e...

Satellite hyperspectral imagery and especially missions like CHRIS Proba provide new capabilities for environmental and geological studies since they offer high spectral and spatial resolution. This work exploits the potential of CHRIS Proba data to be used for classification purposed of areas with high geological interest. For this purpose differe...

Ο ολοκληρωμένος πολεοδομικός σχεδιασμός απαιτεί την πολύ καλή γνώση των χαρακτηριστικών του χώρου και τη διατύπωση λύσεων για την εξασφάλιση ανθρώπινων συνθηκών διαβίωσης. Στα πλαίσια αυτά απαιτούνται προτάσεις για την προστασία του δομημένου περιβάλλοντος από φυσικά καταστροφικά φαινόμενα και χρειάζεται ολοκληρωμένη γνώση των εδαφικών συνθηκών θεμ...

During August of 2007 several areas of Western Greece suffered one of the most devastating wildfires that have ever happened on European level. About 870 thousands of hectares, mainly forest and agricultural land, were lost, 63 people lost their lives, hundreds were injured and many towns and villages suffered extensive damage. Heavy and prolonged...

On the 8th of June 2008 an earthquake of magnitude Ms=6.5 occurred in Western Greece, affecting Achaia and Ilia Prefectures. According to state reports 2 casualties occurred, 214 people were injured and more than 15 villages and towns suffered extensive damages in properties and infrastructures. Among the secondary phenomena that were reported were...

In August 2007 Ilia Prefecture suffered one of the most devastating wildfires that have ever happened on European level. Approximately 870km2 , mainly forest and agricultural land, were lost, more than 60 people were killed, hundreds were injured and many villages suffered extensive damage. Heavy rainfall and human activities, favoured by the loss...

Landslides in the Gulf of Corinth rift zone, Greece, are mainly in the vicinity of major active faults. The current study reports a representative landslide in this structurally controlled region which periodically moved, triggered/reactivated by heavy rainfall and earthquake activity. The composite landslide developed on structurally complex forma...

A large number of laboratory tests were performed on intact chemical and clastic sedimentary rocks (marlstones, sandstones and limestones). Index properties such as total porosity, dry unit weight, Schmidt hammer value and point loading index as well as the strength under uniaxial and triaxial compression were determined. The material constant mi w...

With an ever-decreasing source of aggregate, this study reports laboratory tests on geologically young material, some of which is unconsolidated, in order to determine whether they can be used as aggregates. Los Angeles abrasion and aggregate impact values were compared and correlations made between these parameters and the petrographic composition...

This paper discusses a method of soil suitability estimation for housing purposes in landslide-prone areas based on engineering geological criteria. The studied places, Karya and Neo Souli villages are located on the eastern part of the city of Patras. Several instability problems were identified triggered by heavy rainfalls, especially during extr...

The mountainous area of Karditsa County, being geologically a representative sample of Olonos- Pindos geotectonic zone, is characterized by rainfall- induced landslides on steep slopes of high relief. After a systematic data inventory concerning landslides and their quantitative expression, the correlation between landslide occurrence and rainfall...

The aim of this paper is to determine the geotechnical properties of clastic sedimentary rocks and especially sandstones which constitute a great part of the flysch formation. Laboratory tests were conducted in samples collected from different sites in western Greece. Physical and mechanical properties were determined including porosity (n), dry de...

The preparation and compilation of an engineering geological map of Patras city wider area, at a scale of 1:5,000 is presented, prepared as a part of a thorough geotechnical study of the broader area of the city for urban planning purposes. In this map, eleven (11) engineering geological units were grouped, based on their lithostratigraphy, physica...

Η παρούσα εργασία περιγράφει μία τεχνική για την ταξινόμηση των εδαφών σύμφωνα με τη ρυπαντική επιδεκτικότητα που εμφανίζουν, χρησιμοποιώντας τη συσκευή της υδραυλικής διαπερατότητας. Η τεχνική αυτή εφαρμόζεται στο εργαστήριο, εκτελώντας εργαστηριακές δοκιμές σε κορεσμένα εδαφικά διαταραγμένα δείγματα και διερευνώντας ταυτόχρονα τους μηχανισμούς δι...

Representative landslide phenomena in western Greece induced by heavy rainfalls, in terms of the geological composition and structure of the affected materials, are thoroughly studied and analyzed. The studied cases involved composite landslides on weathered mantle of flysch and Neogene marls that constitute the most critical landslide prone geolog...

The city of Patras in western Greece has experienced several destructive earthquakes during the past centuries. The engineering geological conditions of the area have been analyzed and described using a relational geotechnical database management system including geotechnical and geological information obtained from exploratory boreholes, cone pene...

Landslide occurrences in Greece, covering a long time period (1950–2004) 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, regard...

This study presents the results of laboratory testing of sedimentary rocks under point loading as well as in uniaxial and triaxial compression. From the statistical analysis of the data, different conversion factors relating uniaxial compressive and point loading strength were determined for soft to strong rocks. Additionally, the material constant...

This study presents the results of Cone Penetration Tests (CPT) and estimated correlations with the results of other in-situ tests (standard penetration test, cross-hole, seismocone) and laboratory tests (classification and undrained shear strength tests). These tests cover nearly all types of penetrable soils in Greece and, together with the formu...

The 1999, Ms=5.9, Athens earthquake caused serious structural damage to buildings in the western part of Athens, Greece. This paper presents the ground zoning against seismic hazard proposed shortly after the earthquake in order to aid reconstruction of the area. Existing engineering geological and geotechnical data were combined with local observa...

 Engineering geological information including geotechnical and geological data from exploratory boreholes and trial pits located in the wider area of Athens were stored in a database system. Based on the data processing and field mapping, the geological formations encountered in the foundation materials of the city were divided into individual geot...

For the study and statistical analysis of landslide phenomena in the Greek territory a 'data base' was created after codification and record of 1200 cases. Furthermore, the frequency distribution of various landslide control parameters was investigated and the results are presented in the form of histograms. All parameters controlling the landslide...

The engineering geological investigation which was carried out in the broader area of the city of Patras included the drilling of sampling boreholes as well as in situ and laboratory testing (cone penetration tests, cross-hole tests, soil classification and laboratory tests) for the determination of a representative geotechnical model for the urban...

The paper presents the successive stages of the methodology which has been adopted for the interpretation of findings of an extensive geotechnical site investigation. This investigation was carried out in the urban area of the town of Kalamata, S.W Greece subsequent to the catastrophic earthquakes which occured in the area during September 1986. Th...

Presents measurements and correlations of pressuremeter tests with values of shear wave velocity and dynamic shear moduli obtained by the Cross-Hole method in clayey soils. Since pressuremeter testing can be carried out in a very wide range of soils and weak rocks, correlations from pressuremeter ress are considered to be more reliable for a wide r...

The paper presents measurements of shear wave velocity and dynamic shear moduli obtained by the Cross Hole method, in a very soft clay deposit. The measurements are correlated with results from static cone penetration tests, pressuremeter tests, field vane tests and undrained triaxial tests. The N(SPT) values measured at the site were very low and...