Mineralogical and Geochemical Properties of Greek Evaporites, Associated with Their Prospects of Industrial Use

Greece is considered as one of the most common producers of gypsum-anhydrite in Europe. The low content of impurities of these evaporite minerals, their big reserves and the low cost of logistics costs makes them exploitable and applicable for a range of industrial uses. The current study endeavors to present the petrographic, mineralogical, geochemical and qualitative features of evaporite samples from seven selected localities of western Greece (Zakynthos Island, Filiates-Thesprotia, Etoloakarnania and Kyllini region) and Crete Island. The studied evaporitic rocks are classified as a mixture of gypsum and anhydrite, where gypsum predominates. Other minerals present in minor amounts include celestite ± calcite ± dolomite ± magnesite ± sanidine and quartz. Celestite (SrSO4) was detected in all studied samples. The highest celestite value (13.5%) corresponds to the region of Filiates, indicating that this deposit is prosperous for further research and potential Sr exploitation. Significant focus is also given on the assessment of the evaporite whiteness with respect to their mineralogical and geochemical composition. The aforementioned data aim to serve the dynamic Greek calcium sulphate industry by enhancing the evaporites’ prospects of industrial use, providing potential applications for those not already exploited.

Analyzing and Forecasting Lightning Flashes and the Related Wind Gusts at a Wind Energy Power Plant in a Hilly Region of Western Greece

Wind energy power plants are vulnerable, among others, to abrupt weather changes caused especially by thunderstorms associated with lightning activity and the accompanying severe wind gusts and rapid wind direction changes. Due to a range of damages such phenomena may cause, the knowledge of the relationship between the storm systems and the produced wind field is essential to establish a wind power plant during the construction and operation phase as well. In first part of this study, the relationship of severe wind gusts in regard to lightning activity in a wind farm in a hilly region of western Greece is investigated. Wind data come from wind turbines covering a period of three years (2012-2014), while the corresponding lightning data from the ZEUS lighting detection network. The analysis shows that wind gusts are well correlated to lightning strikes. Furthermore, correlation maximizes during winter when well organized weather systems affect the area and minimum in summer as a result of local storms due to thermal instability. In the second part the study focuses on the development of an ANN model in order to forecast these two parameters in a horizon of 1-h ahead by using except for the wind data, four variables namely CAPE, TTI, wind speed at the 500 hPa isobaric level and the 0-6 km vertical wind shear. The results revealed that proposed model could be considered as a promising tool in simulating the occurrence both of wind gusts and lightning flashes providing a relatively good evidence of the possibility of occurrence of such events.

Preliminary Forecasting of Rainfall-Induced Shallow Landslides in the Wildfire Burned Areas of Western Greece

A new methodology for shallow landslide forecasting in wildfire burned areas is proposed by estimating the annual probability of rainfall threshold exceedance. For this purpose, extensive geological fieldwork was carried out in 122 landslides, which have been periodically activated in Western Greece, after the devastating wildfires that occurred in August 2007 and burned large areas in several parts of Western Greece. In addition, daily rainfall data covering more than 40 years has been collected and statistically processed to estimate the exceedance probability of the rainfall threshold above which these landslides are activated. The objectives of this study are to quantify the magnitude and duration of rainfall above which landslides in burned areas are activated, as well as to introduce a novel methodology on rainfall-induced landslide forecasting. It has been concluded that rainfall-induced landslide annual exceedance probability in the burned areas is higher when cumulative rainfall duration ranges from 6 to 9 days with local differences due to the prevailing geological conditions and landscape characteristics. The proposed methodology can be used as a basis for landslide forecasting in wildfire-affected areas, especially when triggered by rainfall, and can be further developed as a tool for preliminary landslide hazard assessment.