Rainfall and landslides in Karditsa county (Greece): a statistical approach

Η ορεινή περιοχή του Νομού Καρδίτσας ανήκει στη γεωτεκτονική ζώνη Ωλονού- Πίνδου και διακρίνεται για τη σύνθετη γεωλογική δομή, το έντονο ανάγλυφο και τις υψηλές βροχοπτώσεις, συνθήκες που διευκολύνουν την εκδήλωση συχνών και σοβαρών κατολισθήσεων. Με σκοπό την έρευνα των φαινομένων αυτών σε σχέση με τις βροχοπτώσεις, δημιουργήθηκε βάση δεδομένων από 425 περιπτώσεις κατολισθήσεων ενώ παράλληλα αξιολογήθηκαν στατιστικά στοιχεία βροχόπτωσης από 21 μετεωρολογικούς σταθμούς. Από τα παραπάνω γίνεται φανερό ότι το μέσο ετήσιο ύψος βροχόπτωσης συνδέεται άμεσα με τη συχνότητα εκδήλωσης των κατολισθήσεων. Τέλος, διερευνάται μία χαρακτηριστική περίπτωση κατολίσθησης που εκδηλώθηκε μετά από ισχυρές βροχοπτώσειςThe 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 is investigated. Following the analyses performed a close interrelation between landslides and precipitation is established. Finally, a characteristic example of rainfall- induced landslide in the wider area of the county is give

Structural Damage in a Populated Area due to an Active Fault

The city of Patras was struck in August 1989 by a shallow earthquake of MS= 4.8 which caused a surface rupture and serious structural damage to several buildings located in a narrow elongated zone. A detailed investigation programme was carried out including geological mapping, drilling of boreholes, in situ and laboratory testing and monitoring of horizontal and vertical movements. It was found that the surface rupture, about 1500 m long, was closely related with the reactivation of a preexisting normal fault. The structural damage of buildings was found to be limited mainly in a narrow zone 50 m wide along the fault and connected with its movements and the seismic intensity

Landslide susceptibility mapping using the Rock Engineering System approach and GIS technique: an example from southwest Arcadia (Greece)

The purpose of this study is to prepare a susceptibility map in a landslide-prone area in Greece using Rock Engineering System (RES) and a geoprocessing tool called Model Builder. The implementation of RES is achieved through an interaction matrix, where ten parameters were selected as controlling factors for the landslide occurence. The validation of the developed model was achieved by using field-verified data, showing excellent correlation between the expected and existing landslide susceptibility level. In conjunction with Model Builder, which can overlay different layers and produce landslide susceptibility maps, RES can act as a tool for calculating the instability index and getting a prognosis of a potential slope failure in relation to sustainable development planning processes in landslide susceptible areas

ENGINEERING GEOLOGICAL AND GEOTECHNICAL INVESTIGATION OF LANDSLIDE EVENTS IN WILDFIRE AFFECTED AREAS OF ILIA PREFECTURE, WESTERN GREECE

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 of vegetation and the overall susceptibility of geological formations in landsliding, induced the manifestation or reactivation of various scale landslide phenomena. In order to investigate and mitigate the problem University of Patras was commissioned by the Region of Western Greece to undertake an Engineering Geological and Geotechnical investigation. Site investigation accomplished in seven municipalities focusing on several landslide events with serious socio-economic impact and as a result many small scale cases were identified. In each one of these cases large scale engineering geological mapping was conducted and remedial and protection measures were designed