Evaluating the Degradation of Natural Resources in the Mediterranean Environment Using the Water and Land Resources Degradation Index, the Case of Crete Island

Natural resources degradation poses multiple challenges particularly to environmental and economic processes. It is usually difficult to identify the degree of degradation and the critical vulnerability values in the affected systems. Thus, among other tools, indices (composite indicators) may also describe these complex systems or phenomena. In this approach, the Water and Land Resources Degradation Index was applied to the fifth largest Mediterranean island, Crete, for the 1999–2014 period. The Water and Land Resources Degradation Index uses 11 water and soil resources related indicators: Aridity Index, Water Demand, Drought Impacts, Drought Resistance Water Resources Infrastructure, Land Use Intensity, Soil Parent Material, Plant Cover, Rainfall, Slope, and Soil Texture. The aim is to identify the sensitive areas to degradation due to anthropogenic interventions and natural processes, as well as their vulnerability status. The results for Crete Island indicate that prolonged water resources shortages due to low average precipitation values or high water demand (especially in the agricultural sector), may significantly affect Water and Land degradation processes. Hence, Water and Land Resources Degradation Index could serve as an extra tool to assist policymakers to improve their decisions to combat Natural Resources degradation.

Four New Members of The Family Cytophagaceae: Cryseosolum Histidinii gen. nov., sp. nov., Cryseosolum Indiensis gen. nov., sp. nov., Reichenbachia Cretensis, gen. nov., sp. nov., and Reichenbachia Soli, gen. nov., sp. nov. Isolated From Diverse Habitat

Four strains isolated, PWU4T, PWU20T, PWU5T and PWU37T were from both of soil in Germany, India and a faces sheep collected in Crete Island, respectively. Cells were Gram-negative, strictly aerobic, rod shaped, grew optimally between 28oC and 34oC, pH between 7.0 and 8.0 without the addition of NaCl. Catalase and oxidase-negative and grew on most mono- and disaccharides, a few polysaccharides and organic acid. The predominant menaquinone was MK-7. Major fatty acid was c16:1 ω7c (PWU4T and PWU20T) and c16:1 ω5c (PWU5T and PWU37T). The DNA G+C content of them were 50.2 mol %; 51.6 mol %; 39.8 mol % and 53.8 mol %, respectively. The 16S rRNA gene sequence analysis revealed that the closest relatives of them are less than 93.8% compared to Ohtaekwangia koreensis 3B-2T and Ohtaekwangia kribbensis 10AOT. It classified in two groups, where PWU4T, PWU20T shared 93.0% and PWU5T, PWU37T shared 97.5% sequence similarity. However, in both groups represent different species on the low average nucleotide identity (ANI) of their genomes, 69.7% and 83.8%, respectively. We proposed that the four strains represent four novel species of two new genera in the family Cytophagaceae. The type species of the novel genus Cryseosolum are Cryseosolum histdinii gen. nov., sp. nov. strain PWU4T (=DSM 111594T=NCCB 100798T), Cryseosolum indiensis sp. nov. strain PWU20T (=DSM 111597T=NCCB 100800T). The type species of the novel genus Reichenbachia are Reichenbachia cretensis gen. nov., sp. nov. strain PWU5T (=DSM 111596T=NCCB 100799T), Reichenbachia soli sp. nov. strain PWU37T (=DSM 111595T=NCCB 100801T).

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.

Characterisation of fault plane and coseismic slip for the May 2, 2020, Mw 6.6 Cretan Passage earthquake from tide-gauge tsunami data and moment tensor solutions

We present a source solution for the tsunami generated by the Mw 6.6 earthquake that occurred on May 2, 2020, about 807thinsp;km offshore south of Crete, in the Cretan Passage, on the shallow portion of the Hellenic Arc Subduction Zone (HASZ). The tide-gauges recorded this local tsunami on the southern coast of Crete island and Kasos island. We used these tsunami observations to constrain the geometry and orientation of the causative fault, the rupture mechanism and the slip amount. We first modelled an ensemble of synthetic tsunami waveforms at the tide-gauge locations, produced for a range of earthquake parameter values as constrained by some of the available moment tensor solutions. We allow for both a splay and a back-thrust fault, corresponding to the two nodal planes of the moment tensor solution. We then measured the misfit between the synthetic and the observed marigrams for each source parameter set. Our results identify the shallow steeply-dipping back-thrust fault as the one producing the lowest misfit to the tsunami data. However, a rupture on a lower angle fault, possibly a splay fault, with a sinistral component due to the oblique convergence on this segment of the HASZ, cannot be completely ruled out. This earthquake reminds us that the uncertainty regarding potential earthquake mechanisms at a specific location remains quite significant. In this case, for example, it is not possible to anticipate if the next event will be one occurring on the subduction interface, on a splay fault, or on a back-thrust which seems the most likely for the event under investigation. This circumstance bears important consequences because back-thrust and splay faults might enhance the tsunamigenic potential with respect to the subduction interface due to their steeper dip. Then, these results are relevant for tsunami forecasting both in the framework of the long-term hazard assessment and of the early warning systems.

Source Process-Related Delays in Earthquake Early Warning for Example Cases in Greece

ABSTRACT We explore a hypothetical zero-latency earthquake early warning (EEW) system in Greece, aiming to provide alerts before warning thresholds of the intensity of ground motion are exceeded. Within the seismotectonic context of Greece, both shallow- and intermediate-depth earthquakes (along the Hellenic subduction zone) are plausible and, thus, examined. Using regionally applicable attenuation relations, we combine and adjust the methodologies of Minson et al. (2018) and Hoshiba (2020) to examine what are the minimum magnitudes required to invoke the warning thresholds at the user site. With simple modeling, we examine how fast an alert can be issued and what is the available warning time when taking into account delays due to finite-fault rupture propagation, alongside other delays. These computations are merged with delays introduced due to the present-day configuration of the Greek national monitoring network (varying spatial density of permanent monitoring stations). This approach serves as a tool to assess the feasibility of an EEW system at specific sites and to redesign the national permanent monitoring network to serve such a system more effectively (we provide results for four sites.). Warning times for on-land crustal earthquakes are found to be shorter, whereas for intermediate-depth earthquakes in Greece an EEW system is feasible (provides warning times of several tens of seconds at large cities, e.g., on Crete Island) even with the current configuration of the national monitoring network, which is quite sparse in the southern part of the country. The current network configuration also provides sufficient early warning (e.g., of the order of 10 s for a warning threshold of 0.05g) at the center of Athens from earthquakes of the eastern Gulf of Corinth—a zone posing elevated hazard in the broader area of the Greek capital. Several additional assumptions and factors affecting the operability of an EEW system in Greece (i.e., source process complexity and uncertainty in attenuation laws) are also discussed.

Identification of potential rockfall sources using UAV-derived point cloud

Recent advances in remote sensing techniques and computer algorithms allow accurate, abundant, and high-resolution geometric information retrieval for rock mass characterization from 3D point clouds. The automatic application of the extracted information for local scale rockfall susceptibility assessment, where discontinuities characteristics play a major role in rocky slope stability, requires step by step logical procedures. This paper presents a novel methodology to use the extracted discontinuity set characteristics for a local scale rockfall susceptibility assessment, tailored for Uncrewed Aerial Vehicle (UAV) data acquisition. The method consists of 4 steps: (i) 3D slope model reconstruction using UAV digital photogrammetry, (ii) automatic characterization of discontinuity sets, (iii) slope stability analysis, and (iv) susceptibility assessment using a new Rockfall Susceptibility Index. The proposed method was applied to a road cut rocky slope in a mountainous area of the Samaria National Park, in Crete Island, Greece. Visual validation indicates that the areas of higher and moderate rockfall susceptibility on the 3D model of the rocky slope are adjacent to rockfall source areas marked by the presence of fallen blocks on the foot of the slope. The proposed methodological workflow presents novelties related to the use of point clouds for the estimation of the Rock Quality Designation (RQD) index, the visualization of discontinuity set spacing, the evaluation of the persistence and the Slope Mass Rating (SMR) index, as well as the incorporation of the persistence of overhangs into the rockfall susceptibility assessment and visualization.