Search Results (15)

As a crucial strategy for mitigating climate change and achieving electricity independence, renewable energy sources (RESs) are gaining widespread importance. This study explores achieving electricity autonomy for Nisyros Island, Greece, through RESs. Four scenarios are evaluated, including standalone wind and photovoltaic systems, alongside hybrid options combining both. Each scenario is designed to meet the island’s electricity demands while considering economic feasibility and minimal environmental impact. The research findings are that wind-based scenarios offer the most cost-effective solutions, with a three wind turbine setup emerging as the most economical option for full coverage of electricity demands. Hybrid approaches, particularly those incorporating more wind turbines, are also financially viable. Real-world consumption data are integrated into the analysis, providing valuable insights for Nisyros’ energy future. Overall, the study demonstrates Nisyros’ potential to achieve electricity independence through RESs, with wind resource assessments suggesting that the island could become autonomous. This approach would promote environmental sustainability by reducing the given dependence on fossil fuels. Additionally, it would bring economic benefits for the island’s residents in the renewable energy sector. Furthermore, this work allows for the island to achieve electricity independence through renewable energy in alignment with the EU’s climate goals. Full article

The Holy Monastery of Panagia Spiliani is an important religious monument of the Aegean islands. The monastery is built on a steep rocky hill in the Castle of Mandraki on Nisyros island. On the slopes of the foundation area of the monastery, landslides have occurred in the past, mainly rockfalls and slides, while the risk of new similar phenomena in the future is high. To assist the geohazard assessment and mitigation design works, a combined survey using Terrestrial Laser Scanning (TLS) and Unmanned Aerial Vehicle (UAV) photogrammetry was implemented. Besides capturing the detailed morphology within high-resolution 3D point clouds, the main engineering geological units were identified on the slopes, while critical structural ground elements and unstable blocks were mapped in detail. These were quantified in terms of geotechnical parameters, and the engineering geological model of the hill was finalised and presented in an engineering geological map and cross sections. The mitigation measures are targeted towards the stabilisation of the wider area of the upper slope, hence the stability of the monastery and its surroundings risk elements, as well as the support of specific, large- to small-scale unstable rock blocks on the whole slope area, securing accessibility to the main beach of the village. Full article

Rainfall variability, exacerbated by climate change, poses significant challenges to water resource management, particularly in regions prone to intense droughts and floods. The Greek islands, characterized by poor water potential, face interannual water supply issues dating back to their earliest habitation. Rainwater harvesting (RWH) systems emerge as a promising solution to address water scarcity in these regions. This study simulates RWH systems for two small Greek islands, Fourni and Nisyros, representing similar rainfall regimes. Multiple scenarios are explored, and system reliability is assessed in light of simulated daily rainfall time series incorporating climate change projections. Utilizing eight low/medium (RCP 4.5) and eight high (RCP 8.5) emission scenarios over a future 35-year period, the study evaluates system reliability based on model parameters (collection area: 40 to 140 m², rainwater tank volume: 5 to 30 m³, number of household members: 2, 3), with 30% coverage of total daily water demand (180 L/d). Negligible evapotranspiration effects are assumed due to closed-type tanks. Results indicate that the RWH system demonstrates high efficiency in general. The investigation for the future period revealed that the system’s performance varies, with instances where daily demand targets are not met, even with a 30 m³ tank. This research underscores the potential of RWH systems as a cost-effective “green” solution, particularly in regions with deficient rainfall regimes. It highlights the importance of localized water management strategies, reducing reliance on mainland water transportation, and assisting desalination unit operations. In conclusion, this study contributes to the assessment of RWH systems, demonstrating their viability as a sustainable water management solution in regions facing water scarcity, contingent on local rainfall conditions and system design parameters. Full article

This paper presents an integrated methodology for decision making in smart grid investments that assesses the investment plans of stakeholders in local energy communities (LECs). Considering the energy flow exchanges of the LECs and interpreting them in terms of technical benefits and costs, this methodology indicates the most sustainable and profitable solution covering the LEC energy transition plans. A set of specialized tools capturing the energy, environmental, financial, and social impacts are integrated under a common platform called the IANOS Energy Planning and Transition (IEPT) suite. The tools evaluate a set of well-defined key performance indicators that are gathered using a cost–benefit analysis (CBA) module offering multilateral assessment. By upgrading the functionalities of specialized tools, i.e., the energy modeler INTEMA, the life cycle assessment and costing tool VERIFY, and the smart grid-oriented CBA tool, the IEPT suite evaluates the viability of different smart grid investment scenarios from a multi-dimensional perspective at the LEC level. The functionalities of the proposed suite are validated in the LEC of Nisyros island, Greece, where three smart grid-based investment scenarios of different self-consumption levels are evaluated and ranked in terms of benefits and profitability. The results highlight that for a 20-year horizon of analysis, the investment scenario where a 50% self-consumption target is achieved was more financially viable compared to the 80% and 95% scenarios, achieving values of BCR and NPV equal to EUR 2.12 and EUR 4,400,000, respectively. Full article

Weather prediction is a key aspect of today’s society and its activities. Accurate predictions are crucial for efficiently organizing human activities, particularly in the agricultural, transportation and energy sectors. In this paper, two deep neural networks, designed based on a long short-term memory architecture, are developed to predict the occurrence of rainfall events and the respective amount of rainfall on the island of Nisyros in the south Aegean Sea. Two deep neural networks are developed, serving two different learning tasks. The first network acts as a classifier that assesses whether it is going to rain or not and, sequentially, the second network performs a regression task, quantifying the anticipated amount of rainfall. The performance of such prediction models is highly dependent on input sequences. Among others, the lookback time window shapes those input sequences by determining the number of past time steps to be taken into account. The ideal time window for the classifier involves 24 time steps (i.e., 4 h), resulting in increased accuracy levels exceeding 96.45%. The predictions of the regression model, which has the same lookback time window, feature low errors, measured as 6.635 and 1.411 mm using the mean-square-error and mean-absolute-error indices, respectively. Full article

A new assessment method named GEOAM (geoeducational assessment method), that will be a useful tool for highlighting the geoeducational and geoethical value of a geosite, is proposed. This method takes into account, initially, 11 criteria, which are grouped into 8 categories. Each criterion addresses a different aspect of the geosite’s potential for promoting sustainable development, environmental management, and education. A simplified scoring system using a scale of 1–5 is used, where each criterion is scored based on the degree to which it is presented or implemented. The method was piloted in eight geotopes of the Kalymnos Island and five geotopes of the Nisyros Island, in the SE Aegean Sea, Greece. The implementation of this assessment method highlighted the geoeducational value of these geosites. Based on the criteria and subcriteria incorporated in GEOAM, this paper discusses GEOAM’s potential to promote sustainable development and rational environmental management by directing educators and stakeholders toward actions that conserve and protect geoheritage for future generations, while also contributing to the economic, social, and cultural development of the surrounding communities. By quantifying the geoeducational potential of geosites and integrating essential concepts such as geoconservation and geoethics, the implementation of this new assessment method can benefit the educational community, tourism industry, and environmental conservation efforts. Full article

Greece exhibits the highest seismic activity in Europe, manifested in intense seismicity with large magnitude events and frequent earthquake swarms. In the present work, we analyzed the spatiotemporal properties of recent earthquake swarms that occurred in the broader area of Greece using the Non-Extensive Statistical Physics (NESP) framework, which appears suitable for studying complex systems. The behavior of complex systems, where multifractality and strong correlations among the elements of the system exist, as in tectonic and volcanic environments, can adequately be described by Tsallis entropy (S_q), introducing the Q-exponential function and the entropic parameter q that expresses the degree of non-additivity of the system. Herein, we focus the analysis on the 2007 Trichonis Lake, the 2016 Western Crete, the 2021–2022 Nisyros, the 2021–2022 Thiva and the 2022 Pagasetic Gulf earthquake swarms. Using the seismicity catalogs for each swarm, we investigate the inter-event time (T) and distance (D) distributions with the Q-exponential function, providing the q_T and q_D entropic parameters. The results show that q_T varies from 1.44 to 1.58, whereas q_D ranges from 0.46 to 0.75 for the inter-event time and distance distributions, respectively. Furthermore, we describe the frequency–magnitude distributions with the Gutenberg–Richter scaling relation and the fragment–asperity model of earthquake interactions derived within the NESP framework. The results of the analysis indicate that the statistical properties of earthquake swarms can be successfully reproduced by means of NESP and confirm the complexity and non-additivity of the spatiotemporal evolution of seismicity. Finally, the superstatistics approach, which is closely connected to NESP and is based on a superposition of ordinary local equilibrium statistical mechanics, is further used to discuss the temporal patterns of the earthquake evolution during the swarms. Full article

Nisyros Geopark, an island geopark in the Southeastern Aegean Sea, Greece, is here presented as an official candidate for the UNESCO Global Geoparks designation, featuring outstanding geological, natural and cultural characteristics tightly connected to its volcanic origin. It covers a total area of 481 km² and includes Nisyros, an active volcano and the main island, the surrounding islets of Pachia, Strongyli, Pergousa, Kandeliousa and the marine region among them. It features 24 geosites and a network of well-established walking trails. Furthermore, there are two internationally designated Natura 2000 areas covering its entire surface and also exceptional archaeological and cultural sites, including fortresses, remnants of ancient habituations and numerous churches and monasteries. It is the only area in the broader region of the Eastern Mediterranean that hosts all these features within such a restricted area. The initial efforts of the management body of Nisyros Geopark and its scientific team to promote its unique geodiversity included the complete design, construction and launch of the official website, the mobile application “Nisyros Volcano App’’, a modern informative leaflet regarding the region of the hydrothermal craters (Lakki), a Geopark guidebook and a series of panels and signs for the geosites. Full article

In this study, the geoeducational value of five geosites, located in the aspiring geopark of the volcanic island of Nisyros, SE Aegean Sea, was assessed by means of two methods: the G-P method of Brilha (2016) and the M-GAM method. The first method takes into account 12 criteria belonging to the educational potential. The M-GAM method, on the other hand, takes into account the opinions of visitors who, as non-experts, express a different point of view that is rarely calculated or evaluated in different geosite assessment methods. For the better and more objective comparison of the two methods of evaluation of the educational potential of the study areas, the results were converted to a percentage scale (%). The first G-P method clearly highlights the high geological value of the studied geosites, which have a relatively high score and can be used for geotourism and geoeducation. The second method, on the other hand, yields a moderate score in areas with objectively high geological value. This is clearly evident, as this method considers the opinions of visitors who lack the necessary cognitive geological background, thereby underestimating the significance and potential of certain geological features due to lack of formal training. Full article

Almost three-quarters of known volcanic activity on Earth occurs in underwater locations. The presence of active hydrothermal vent fields in such environments is a potential natural hazard for the environment, society, and economy. Despite its importance for risk assessment and risk mitigation, the monitoring of volcanic activity is impeded by the remoteness and the extreme conditions of many underwater volcanoes. The morphology and the activity of the submarine caldera, Avyssos, at the northern part of Nisyros volcano in the South Aegean Sea (Greece), were studied using a remotely operated underwater vehicle. The recorded time series of temperature and conductivity over the submarine volcano have been analyzed in terms of the Generalized Moments Method. This type of analysis can be used as an indicator for the state of activity of a submarine volcano. Here, we expand the work conducted for the first time in 2018. We present the findings of the geological exploration and the mathematical analysis, obtained from the data collected in October 2010. The temperature and conductivity time series show minor fluctuations in a rather stable environment. Based on these results, the impact of developing appropriate mechanisms and policies to avoid the associated natural hazard is expected to be important. Full article

The active Kos-Nisyros-Tilos volcanic field is located in the eastern sector of the Aegean Volcanic Arc resulting from the subduction of the African plate beneath the Aegean plate. The volcanic activity is developed since Middle Pleistocene and it occurs within a tectonic graben with several volcanic outcrops both onshore and offshore. Data obtained from previous offshore geophysical surveys and ROV exploration, combined with geospatial techniques have been used to construct synthetic maps of the broader submarine area. The volcanic relief is analyzed from the base of the volcanic structures offshore to their summits onshore reaching 1373 m of height and their volumes have been computed with 24.26 km³ for Nisyros Island and a total volume of 54.42 km³ for the entire volcanic area. The volcanic structures are distinguished in: (1) volcanic cones at the islands of Nisyros (older strato-volcano), Pergousa, Yali and Strongyli, (2) volcanic domes at the islands of Pachia, East Kondeliousa and Nisyros (younger Prophitis Ilias domes), (3) submarine volcanic calderas (Avyssos and Kefalos). Submarine volcanic debris avalanches have been also described south of Nisyros and undulating features at the eastern Kefalos bay. Submarine canyons and channels are developed along the Kos southern margin contrary to the Tilos margin. Ground truth campaigns with submarine vessels and ROVs have verified the previous analysis in several submarine volcanic sites. The geohazards of the area comprise: (1) seismic hazard, both due to the activation of major marginal faults and minor intra-volcanic faults, (2) volcanic hazard, related to the recent volcanic structures and long term iconic eruptions related to the deep submarine calderas, (3) tsunami hazard, related to the seismic hazard as well as to the numerous unstable submarine slopes with potential of gravity sliding. Full article

The volcanic island of Nisyros (Greece) is here presented as it presents unique characteristics being a Quaternary volcano in the eastern Aegean Sea, composed of volcanic rocks, and featuring a central caldera that is surrounded by volcanic domes and thick lavas. Its history is strongly connected to the volcano impressing the visitors with steaming hydrothermal craters, intensive smell of sulfur and fumarolic gases, and hot springs. Due to its morphology and geographical position, its cultural and historical heritage has been unchanged in time, bequeath to the island plenty of churches, monasteries with hagiographic frescoes, castles, caves, and spas. To present the geodiversity, the cultural environment, and the biodiversity of this geosite, a relatively new geographic approach was used, ESRI Story Maps. Being web-based applications, they are widespread as an interactive responsive tool used for spatial data communication and dissemination, by combining thematic 2D and 3D webmaps, narrative text, and multimedia content. Such applications can be an ideal way for presenting the available information of places characterized as geosites or protected areas worldwide, providing quick access to the available information to a broader, non-technical audience, developing the interest, and possibly motivating the public to learn more or visit them. Full article

The aim of this study was to propose a methodology that provides a detailed description of the argillic zone of a hydrothermal field, based on satellite multispectral data. More specifically, we developed a method based on spectral unmixing where hydroxyl-bearing alteration is represented by a single endmember (representing clays) and the three (nearly) non-altered primary volcanic lithologies, namely, two types of lava flows (basic and acidic compositions) and the loose materials (alluvial/beach deposits, scree, pyroclastic deposits, etc.), are represented by three endmembers. We also used one endmember representing elemental sulfur that is present in fumarolic vents hosted by active hydrothermal craters. The methodology was applied in the south part of Lakki plain inside the Nisyros volcano caldera (Greece), using Sentinel-2, Landsat-8/OLI, and ASTER satellite multispectral datasets. Specifically, it was applied separately to each one of the three datasets. The spectral unmixing results, combined with the relative geological map, provide quantitative estimations of the primary volcanic and loose material areas affected by alteration. In addition, pixels with high abundance values of hydroxyl-bearing alteration corresponded to mapped areas with strong hydrothermal alteration. The developed methodology is superior to conventional approaches (e.g., alteration spectral index) in terms of its ability to describe the overall pattern of the hydrothermal field. The most accurate results were taken when applied to ASTER or Sentinel-2 MSI data. Full article

The Eemian was the last interglacial period (~130 to 115 ka BP) to precede the current interglacial. In Eastern Mediterranean marine sediments, it is marked by a well-developed and organic-rich “sapropel” layer (S5), which is thought to reflect an intensification and northward migration of the African monsoon rain belt over orbital timescales. However, despite the importance of these sediments, very little proxy-independent stratigraphic information is available to enable rigorous correlation of these sediments across the region. This paper presents the first detailed study of visible and non-visible (cryptotephra) layers found within these sediments at three marine coring sites: ODP Site 967B (Levantine Basin), KL51 (South East of Crete) and LC21 (Southern Aegean Sea). Major element analyses of the glass component were used to distinguish four distinct tephra events of Santorini (e.g., Vourvoulos eruption) and possible Anatolian provenance occurring during the formation of S5. Interpolation of core chronologies provides provisional eruption ages for the uppermost tephra (unknown Santorini, 121.8 ± 2.9 ka) and lowermost tephra (Anatolia or Kos/Yali/Nisyros, 126.4 ± 2.9 ka). These newly characterised tephra deposits have also been set into the regional tephrostratigraphy to illustrate the potential to precisely synchronise marine proxy records with their terrestrial counterparts, and also contribute to the establishment of a more detailed volcanic history of the Eastern Mediterranean. Full article

The morphology and the activity of a submarine caldera, Avyssos, at the northern part of Nisyros volcano in the South Aegean Sea (Greece), has been studied by means of remotely-operated underwater vehicle dives. The recorded time series of temperature and conductivity over the submarine volcano have been analyzed in terms of the generalized moments method. The findings of the mathematical analysis shed light on the volcanic activity, but also on the morphology (shape) of the submarine volcano. The conductivity time series indicates that the volcano is at rest, in agreement with other types of observations. On the other hand, temperature fluctuations, which in general describe a multifractal process, show that the submarine caldera operates as an open system that interacts with its surroundings. This type of analysis can be used as an indicator for the state of activity and the morphological structure (closed or open system) of a submarine volcano. Full article