n July 25 and August 26 2016 wildfires broke out in the southwestern and central-western part of Chios Island(NE Aegean Sea, Greece), respectively. The first affected an area of approximately 47km2 and burned throughalmost 90% of olive groves and mastic trees, while the second broke out in a forested area and affected approximately6.6km2 of forest and farmland.A research aiming at the post-fire landslide susceptibility (LS) mapping of both areas was conducted. Morphologicaldata (slope, aspect, curvature, drainage network) derived from a 5m-DEM model of the areas was used.Lithological and geological data (lithology, tectonic structures) were digitized from previous field work maps.Land cover was derived from Worldview-2 satellite images before and after the fire events. Soil thickness was derivedfrom field survey observations within the fire-affected areas, road network from OpenStreetMap and rainfalldata resulted from related measurements derived from Chios meteorological station. Post-fire landslide inventorywas created after an extensive field survey of both areas before the beginning of the rainfall period (October 2016)and before the end of winter season (February 2017).Data classification of each factor according to their estimated LS followed, by using the reverse ranking method,where 1 is the least susceptible and 10 is the most one. Each category was normalized to 100% and the final rasterthematic maps of landslide controlling factors were produced. Finally, using numerical weight for each factor,which was assigned by the Analytic Hierarchy Process using Pairwise Comparison Method and according to theweighted linear combination, a map was generated where each cell has a certain post-fire LS index (LSI) value.The higher the LSI value, the higher the LS, whereas lower LSI value means lower LS.This procedure was repeated twice, first using pre-fire land cover and secondly using the severity of the fire events.The resulted maps, classified with natural breaks method, constitute the final pre- and post-fire LS maps of theaffected areas with five LS categories: very low, low, moderate, high and very high.Comparison of these two final maps showed, more or less, the same LS areas, but with LSI value enhanced. Thevalidated results showed good agreement between post-fire landslide occurrence and the produced post-fire LS maps.
Although forest fires are an integral part of Mediterranean forest ecosystems, they constitute one of the most devastating natural hazards in the region. Apart from the direct consequences, fires induce well-documented longer term effects in the geomorphological and hydrological processes, influencing environmental factors that in turn can affect the occurrence of other natural hazards, such as floods and mass movement phenomena.This work focuses on the forest fire of 2007 in Peloponnese, Greece that burnt 1773 km2, causing 78 fatalities and very significant damages in property and infrastructure and went down as the largest fire in the country’s record. It examines the occurrence of flood and mass movement phenomena, before and after this mega-fire and studies different influencing factors to investigate the degree to which the 2007 fire and/or other parameters have affected their frequency.Observational evidence based on several data sources collected during the period 1989-2016 show that the 2007 fire has contributed to an increase of average flood and mass movement events frequency by approximately 3.3 and 5.6 times respectively.Fire affected areas record a substantial increase in the occurrence of both phenomena, presenting a noticeably stronger increase compared to neighbouring areas that have not been affected. Examination of the monthly occurrence of events showed an increase even in months of the year were rainfall intensity presented decreasing trends.Although no major land use changes has been identified and chlorophyll is shown to recover 2 years after the fire incident, differences on the type of vegetation as tall forest has been substituted with lower vegetation are considered significant drivers for the observed changes in hydrogeomorphic response of the fire affected basins.The findings of this work are strong indications that future climatic change, with more frequent and severe droughts and storms will be a disastrous combination for the Mediterranean region.
Chrysafis I, Christopoulou A, Kazanis D, Farangitakis G-P, Mallinis G, Mitsopoulos I, Arianoutsou M, Emm. V, Antoniou V, Theofanous N, et al.
Remote sensing techniques offer the opportunity to study fire effects and vegetation recovery dynamics across large areas, providing essential information for effective management strategies development over fire-prone landscapes. Chios, the fifth largest of the Greek islands, has experienced recurring forest fires during the recent years, resulting to significant risk of environmental degradation. During the summer of 2016, the island experienced two severe wildfires, with the biggest one recorded in the southern part of the island. The affected area was mostly covered by maquis and phrygana (formations of low shrubs) (40.9%), while pine forests (Pinus brutia) represented 15.5% of the burned area.
The aim of this study was to estimate and analyze the state of post-fire vegetation recovery in the island of Chios following major fire events occurred during the summer of 2016. A post-fire 8-band WorldView-2 image was used for burned area mapping by employing a geographic object-based classification approach, followed by field campaign for assessing post fire vegetation recovery, which was conducted during summer 2017 by establishing reference plots in the main pre-fire vegetation types (maquis, shrublands and pine forest areas) within the fire-affected area.
A series of single and multi-temporal spectral indices including Normalized Burn Ratio, Normalized Difference Vegetation Index, Enhanced Vegetation Index and Soil Adjusted Vegetation Index, were derived from multi-temporal Sentinel-2 images. A random forest modelling procedure was performed for estimating post fire vegetation recovery within the burned area, as well as the areas of high risk erosion.
We identified dNDVI, EVI and the second red edge band of Sentinel-2 as the most important spectral variables for predicting vegetation recovery within pre-fire areas. In the case of pre-fire areas with maquis, post-fire NBR, EVI and NDVI were selected as best predictors. Finally, the results revealed that vegetation recovery is more pronounced within the pre-fire pine forest areas, while topographic and geological sub-strata factors were also found significant in defining post-fire vegetation recovery.
. Journal of Coastal Conservation [Internet]. 2018. pdfAbstract
The long-term change of the shoreline location is a phenomenon, which is highly factored in the design of construction projects along the coastal zone. Especially, beach erosion is characterized as one of the major problems at coastal areas and it is of high importance as a quite significant percentage of social development is concentrated in a relatively narrow zone not far from the waterfront. This study presents a methodology that aims to quantify the shoreline displacement rate by involving the processing of different types of remote sensing datasets such as aerial photographs, satellite images and unmanned aerial system data coupled with in-situ observations and measurements. Several photogrammetric techniques were used in order to orthorectify and homogenize a time series of remotely sensed data acquired from 1945 to 2017, representing a rapidly relocating coastal zone at the southern part of Corinth Gulf (Greece), as a case study. All images were digitally processed and optically optimized in order to produce a highly accurate representation of the shoreline at the time period of each acquisition. The data were imported in a Geographic Information System platform, where they were subjected to comparison and geostatistical analysis. High erosion rates were calculated, reaching the order of 0.18 m/year on average whilst extreme rates of 0.70 m/year were also observed in specific locations leading to the segmentation of the coastal zone according to its vulnerability and consequently the risk for further development as well as the effectiveness of measures already taken by the authorities.
Apart from direct consequences, forest fires induce water related effects related to geomorphological and hydrological processes, triggering floods and mass movement phenomena. This work focuses on the forest fire of 2007 in Peloponnese, Greece that to date corresponds to the largest fire in the country’s record. It examines the occurrence of flood and mass movement phenomena, before and after this fire and analyses different influencing factors to investigate the degree to which the 2007 fire and/or other parameters have affected their frequency. Observational evidence collected during the period 1989-2016 show that the 2007 fire has contributed to an increase of average flood and mass movement events frequency by approximately 3.3 and 5.6 times respectively. Fire affected areas record a substantial increase in the occurrence of both phenomena, presenting a noticeably stronger increase compared to neighbouring areas that have not been affected. Examination of the monthly occurrence of events showed an increase even in months of the year were rainfall intensity presented decreasing trends. Although no major land use changes has been identified and chlorophyll is shown to recover 2 years after the fire incident, differences on the type of vegetation as tall forest has been substituted with lower vegetation are considered significant drivers for the observed increase in flood and mass movement frequency in the fire affected areas.
Mitsopoulos I, Chrysafi I, Mallinis G, Vassilakis E, Arianoutsou M, Lekkas E.
. In: 17th Congress of Hellenic Forestry Society. Edessa, Greece; 2017.Abstract
The aim of this study is to spatially assess fire severity and to explore the relationship between the Normalized Vegetation Index (NDVI) derived from WorldView- 2 imagery and the field-based fire severity index “Composite Burn Index” (CBI) on a recent large fire that occurred on the island of Chios, Greece, in 2016. The statistical analysis indicated a relatively strong linear relationship between the NDVI and the CBI (R2 = 0.71). Predictive local thresholds of NDVI values have been determined for accurate thematic classification and mapping of fire severity classes. The overall classification accuracy based on NDVI from WorldView-2 was relatively high (71%), pointing to the potential of using such data for mapping forest fires in the Mediterranean as well as for assessing their severity. The application of the classification thresholds calculated in this study over other forest fire events on similar ecosystem types, could support the rapid assessment of fire severity and hence could enable the decisions needed for proper post-fire management.
The thermal comfort conditions in a complex urban area is influenced by the surrounding structures and obstacles which modify the incoming radiation fluxes. A measure of this modification is the sky view factor (SVF), which could be estimated in each point of a selected area if a high resolution digital elevation model (DEM), or other urban morphological data including the manmade infrastructure, are available. The goal of this study is to model the continuous SVF for a complex building environment in the campus of National and Kapodistrian University of Athens, based on a high resolution DEM (0.09 m). For this purpose, we applied the structure-from-motion (SfM) technique, which takes advantage of the interpretation of ultra-high resolution colour images acquired by remotely piloted airborne systems, also known as drones or unmanned aerial vehicles. A quantitative analysis, by applying statistical metrics, yields perfect agreement between modelled and observed SVF values, over the examined area. The proposed methodology could be applied for human-biometeorology research in micro scale complex urban environments.
Although forest fires are considered an integral part of Mediterranean forest ecosystems, they nevertheless constitute one of the most devastating natural hazards. Apart from the direct consequences, fires induce longer term effects in the geomorphological and hydrological processes, influencing environmental factors that in turn can affect the occurrence of other natural hazards, such as floods and mass movement phenomena. This work focuses on the forest fire of 2007 in Peloponnese, Greece that burnt 1773 km2, causing 78 fatalities and very significant damages in property and infrastructure and went down as the largest fire in the country’s record. It examines the occurrence of flood and mass movement phenomena, before and after this mega-fire and studies different influencing factors to investigate the degree to which the 2007 fire and/or other parameters have affected their frequency.Observational evidence based on several data sources collected during the period 1989-2016 show that the 2007 fire has contributed to an increase of average flood and mass movement events frequency by approximately 3.3 and 5.6 times respectively. Fire affected areas record a substantial increase in the occurrence of both phenomena, presenting a noticeably stronger increase compared to neighbouring areas that have not been affected. Examination of the monthly occurrence of events showed an increase even in months of the year were rainfall intensity presented decreasing trends. Although no major land use changes has been identified and chlorophyll is shown to recover 2 years after the fire incident, differences on the type of vegetation as tall forest has been substituted with lower vegetation are considered significant drivers for the observed changes in hydrogeomorphic response of the fire affected basins.
Even though rare, mega-fires raging during very dry and windy conditions, record catastrophic impacts on infrastructure, the environment and human life, as well as extremely high suppression and rehabilitation costs. Apart from the direct consequences, mega-fires induce long-term effects in the geomorphological and hydrological processes, influencing environmental factors that in turn can affect the occurrence of other natural hazards, such as floods and mass movement phenomena. This work focuses on the forest fire of 2007 in Peloponnese, Greece that to date corresponds to the largest fire in the country's record that burnt 1773 km2, causing 78 fatalities and very significant damages in property and infrastructure. Specifically, this work examines the occurrence of flood and mass movement phenomena, before and after this mega-fire and analyses different influencing factors to investigate the degree to which the 2007 fire and/or other parameters have affected their frequency. Observational evidence based on several data sources collected during the period 1989–2016 show that the 2007 fire has contributed to an increase of average flood and mass movement events frequency by approximately 3.3 and 5.6 times respectively. Fire affected areas record a substantial increase in the occurrence of both phenomena, presenting a noticeably stronger increase compared to neighbouring areas that have not been affected. Examination of the monthly occurrence of events showed an increase even in months of the year were rainfall intensity presented decreasing trends. Although no major land use changes has been identified and chlorophyll is shown to recover 2 years after the fire incident, differences on the type of vegetation as tall forest has been substituted with lower vegetation are considered significant drivers for the observed increase in flood and mass movement frequency in the fire affected areas.
Fires of 2007 have consumed large areas of Black pine and endemic fir forests in Greece. The current research aims at examining the role of geomorphology and lithology that govern the soil properties upon the post-fire vegetation recovery at the landscape level. A case study from Taygetos Mt, a large part of which was burned in 2007, is presented. Based on the interpretation of a high spatial and spectral resolution satellite image (WorldView-3, 4/2015), GIS thematic layers have been created showing unburned and regenerated patches over various lithological types. A network of sites was selected for field sampling representing various combinations of the above. Data on recovery of the main tree species as well as on total vegetation cover were collected. Results prove the relationship between regeneration ability and plant species traits as well as the existence of unburned patches near the burned ones. Black pine had regenerated from seeds dispersed from cones that have remained intact on unburned or scorched trees, close enough to the burned patches, while Greek fir presented remarkably low regeneration, lacking of any response mechanism. Plant species recovery seems to be controlled by the geology as it was found weaker in plots overlying carbonate, permeable, not easily erodible formations as compared to that observed over clastic, impermeable, erodible formations of schists, even for the same species. In conclusion, post-fire vegetation recovery at the landscape level seems to be a complex process controlled not only from species biology but also from the landscape features.
Combining geological and geomorphological data together with geodetic SAR interferometry (InSAR) measurements an attempt has been made to investigate the vertical deformation of the Itea-Amfissa basin at the northern part of the Corinth rift. The north–south trending basin has been developed normally to the east – west trending Corinth Rift and on the hanging wall of the Itea-Amfissa detachment. In the stratigraphy of the Itea–Amfissa supra-detachment basin, two sequences can be distinguished; the lower marine polymict conglomerate of Early–Middle Miocene age and the upper terrestrial monomict carbonate breccia of Late Miocene age. The unconformity between them has been uplifted to the north of the basin up to the elevation of 1100m and subsided below sea level at its southern part. Remnants of low-relief surfaces are retained on top of the upper terrestrial sequence, that permit to reconstruct the paleo-landscape of the basin and to measure the spatial distribution of its vertical deformation after compensating the erosional isostatic adjustment. The exact delineation of the paleo-landscape, involved detailed mapping as well as quantitative analysis of geomorphological features caused by river incision, based on measurements of several tectonic geomorphology indices. Geodetic InSAR estimates of vertical ground displacements, combining almost 10 years of ascending and descending ENVISAT data, were also utilized both for refinement of delineated surfaces as well as for validation of geology-based deformation trends. Interferometric results were constrained to the geologic time frame, considering the well-defined long-term deformation trend of a doline, proven to be sinking over the last 6000 years. It is shown that over the last 10 years the largest uplift rates are observed within the Itea-Amfissa basin, while the coastline regions follow a more complex spatial deformation pattern of successive submergences and uplifts. The synthesis of geological and geomorphological data indicates that the Itea-Amfissa extensional basin from its development in the Middle-Late Miocene and throughout Plio-Quaternary, has been tilted towards south, while contemporary geodetic measurements from InSAR confirm that the basin is still uplifting with regard to its surrounding mountains and coastal areas.
Mt Taygetos (2407m), located at southern Peloponnese (Greece) suffered a large fire during the summer of 2007. The fire burned approximately 45% of the area covered by the endemic Greek fir (Abies cephalonica) and Black Pine (Pinus nigra) forest ecosystems. The aim of the current study is to examine the potential differences on post-fire vegetation recovery imposed by the lithology as well as the geomorphology of the given area over sites of the same climatic and landscape conditions (elevation, aspect, slope etc.). The main lithologies consist of carbonate, permeable, not easily erodible formations (limestones and marbles) and clastic, impermeable (schists, slate and flysch) erodible ones.
A time-series of high spatial resolution satellite images were interpreted, analyzed and compared in order to detect changes in vegetation coverage which could prioritize areas of interest for fieldwork campaigns. The remote sensing datasets were acquired before (Ikonos-2), a few months after (Quickbird-2) and some years after (Worldview-3) the 2007 fire. High resolution Digital Elevation Model was used for the ortho-rectification and co-registration of the remote sensing data, but also for the extraction of the mountainous landscape characteristics.
The multi-temporal image dataset was analyzed through GEographic-Object Based Image Analysis (GEOBIA). Objects corresponding to different vegetation types through time were identified through spectral and textural features. The classification results were combined with basic layers such as lithological outcrops, pre-fire vegetation, landscape morphology etc., supplementing a spatial geodatabase used for classifying burnt areas with varying post-fire plant community recovery.
We validated the results of the classification during fieldwork and found that at a local scale, where the landscape features are quite similar, the bedrock type proves to be an important factor for vegetation recovery, as it clearly defines the soil generation along with its properties. Plant species recovery seems to be controlled by the local lithology as it was found weaker in plots overlying limestones and marbles, comparing to that observed over schists, even for the same species. In conclusion, post-fire vegetation recovery seems to be a complex process controlled not only from species biology, but also from the geological features.
Recent global changes seem to have affected fire regimes by inducing more severe larger fires in the thermomediterranean vegetation zone but also more frequent incidents in territories of higher altitudes. Cephalonia island hosts Mt Ainos, one of the most important National Parks of Greece, focal geographical area of the non-fire adapted endemic fir Abies cephalonica. The island has suffered several fires in the past. The aim of this work is to introduce a framework for assessing spatial fire risk and exposure of biodiversity hot spot areas, using Cephalonia as a pilot case study. Fuel parameters in representative vegetation types were measured across the island for models development as well as for collecting training and validation points for satellite data classification. The Minimum Travel Time algorithm, as it is embedded in FlamMap spatial fire simulation software, was applied in order to assess critical fire behavior parameters and exposure of the island’s biodiversity hotspots under three different meteorological and fuel moisture scenarios simulating predicted climate changes. In addition, the risk of change in the island's ecological value due to biodiversity loss was studied under the same scenarios. According to the analysis, loss of all biodiversity values was found under the severe meteorological and fuel moisture scenario and was estimated to be higher in the endemic fir forests. The outputs of this study may be used as an application of quantitative and probabilistic risk assessment for biodiversity conservation planning, prioritization and management of high value natural and cultural resources.
Fires of 2007 have consumed large areas of Black pine and Greek fir forests in Peloponnese, Euboea and Attica. Most studies that followed, focused on the natural regeneration potential or the need for reforestation. The current research aims at examining the role of geomorphology and lithology that govern the soil properties upon the post-fire vegetation recovery at the landscape level. A case study from Taygetos Mt, a large part of which was burned in 2007, is presented. Based on the interpretation of a high spatial and spectral resolution satellite image (WorldView-3, 4/2015), several GIS thematic layers have been created showing unburned and regenerated patches over various lithological types. A network of sites was selected for field sampling representing various combinations of the above. Data on vegetation cover and recovery of the main tree species were collected. Results prove the interrelationship between regeneration and species traits as well as the existence of unburned patches near the burned ones. Recovery seems to be controlled by the geology of the plots as it was found weaker in plots overlying carbonate, permeable, not easily erodible formations as compared to that observed over clastic, impermeable, erodible formations of schists, even for the same species. In conclusion, post-fire vegetation recovery at the landscape level seems to be a complex process controlled not only from species biology but also from the landscape features and its fire history.
Within this study we introducea framework for assessing spatial fire risk and exposure to three important habitat types in Cephalonia island, Greece.Existing maps were used for plot allocation in orderto measure several fuel parameters in representative natural fuel complexes for site-specific fuel models development, as well as for collecting training and validation points for satellite data classification. The spatial extent of the fuel types and the canopy cover were delineated using a Landsat 8 OLI image acquired on 23-7-2015and the Support Vector Machines-(SVMs) machine learning algorithm. Subsequently, The Minimum Travel Time (MTT) algorithm, as it is embedded in FlamMap spatial fire simulation software, was applied in order to assess critical fire behavior parameters and exposure of Cephalonia's habitats under three different meteorological and fuel moisture scenarios. The outputs of this study may be used as an application of quantitative and probabilistic risk assessment for habitats conservation planning, prioritization and management of high value natural and cultural resources.
On July 17, 2015 a forest fire that broke out in the southern part of Epidavros Limira peninsula (Laconia, southeastern Peloponnese), expanded rapidly due to strong winds blowing in the area and raged out of control for two days, inducing substantial damage to agriculture, livestock farming, buildings and infrastructure and causing one fatality. Innovative GIS-based methods were developed and implemented for the first time in a fire-affected area in Greece for mapping the post-fire erosion, flood and landslide hazards and risks. Geomorphological, geological, tectonic, hydrological, meteorological and land-use data along with a WorldView-2 satellite image and post-fire field observations were evaluated and used. A newly developed method was applied for assessing the erosion hazard. Analytic Hierarchy Process and Weighted Linear Combination methods were used for assessing the post-fire landslide susceptibility. The HEC-RAS model was used for hydraulic simulation and assessment of flood risk under post-fire conditions. Post-fire erosion, flood and landslide hazard and risk maps were constructed for the affected area delineating locations with very low, low, moderate, high or very high hazard and risk of erosion, flood and landslide respectively. The developed methodology is a useful post-fire hazard and risk assessment tool and can be applied by state authorities to assess the geo-environmental impact of fire disasters in areas with similar environmental conditions.
The Aegean-west Anatolian orocline formed due to mainly post-15 Ma opposite rotations of its western and eastern limbs, which contributed to the opening of the Aegean back-arc basin. Stretching lineations in exhumed metamorphic complexes in this back-arc basin mimic the regional vertical axis rotation patterns and suggests that the oppositely rotating domains are bounded by the ‘Mid-Cycladic Lineament’, the tectonic nature of which is enigmatic. Some authors have proposed this lineament to be extensional fault accommodating orogen-parallel extension, while others considered it a transform fault. The island of Paros hosts the only exposure of the Mid-Cycladic Lineament: the northwest of the island contains E-trending and the southeast contains N trending stretching lineations. Here, we show new paleomagnetic results from isotropic, ~16 Ma granitoids that intruded both domains. These demonstrate that the trend difference resulted from post-16 Ma ~90° clockwise and 10° counterclockwise rotation of the northwest and southeast blocks, respectively. We show that a greenschist facies, semi-ductile to brittle, low-angle, southeast dipping normal fault zone, here identified as the Elitas Shear Zone that we interpret as the Mid-Cycladic Lineament accommodates this rotation difference on Paros. We conclude a two-stage exhumation history for Paros that is consistent with regional Aegean reconstructions. Between ~23 and 16 Ma, the metamorphic rocks of Paros exhumed from amphibolite-facies to greenschist facies conditions along a top-to-the-north detachment. The Elitas shear zone then started to exhume the northwestern clockwise rotating domain from below the southeastern, counterclockwise rotating domain since 16 Ma. We demonstrate at the only location at which a structure coinciding with Mid-Cycladic Lineament is exposed, it is extensional in nature, consistent with geometrical predictions that Aegean oroclinal bending must have been accommodated by combined orogen-normal and orogen-parallel extension.
Corinth Canal is an important technical construction with a significant role in marine and land transportation for Greece. Whilst the main highway of the Corinth bridge is well monitored there is no similar monitoring scheme for landslide failures of the canal walls. This work presents an in-house developed real-time early warning landslide triggering system using wireless sensor network (WSN) nodes. Specifically, for the detection of different types of landslide processes (drift, slide and fall) a set of corresponding MEMS (Micro-Electro-Mechanical Systems) sensors (accelerometer, inclinometer, magnetometer) will be used. These sensors along with radio transmission unit and microprocessor comprise a WSN node. The option for in-situ processing (i.e transmitting only alerts) is possible in order to decrease the communication costs. In conjunction with the proposed WSN system, high accuracy geodetic techniques are used with terrestrial laser scanning (TLS) measurements. TLS is augmenting the point-based system to a spatial -based monitoring system. The paper describes the use of WSN node as triggering device in order to alert the users to begin TLS measurements. A description of the network topology is given along with the implementation of the system in selected control points on the canal walls. Real results are shown and the performance of the system is discussed.
The long term change of the shoreline is a phenomenon, which is factored in the design of construction projects along the coastal zone. This study presents a meth-odology that aims to quantify the shoreline displacement rate. The described meth-odology involves the interpretation of different remote sensing data types, which make up a quite dense time series of representations for the coastline spanning from 1987 to 2012. The representation of the shoreline is based on geometrically corrected (ortho-rectified), historical, analogue, panchromatic, high resolution aerial photos of the area (1987, 1996) and latest generation, digital, multispectral, high resolution satellite images (2000, 2008, 2012). In all cases the images were digitally processed and optically optimized in order to produce a highly accurate representation of the shoreline in each time period. All the data were imported in a Geographic Information System platform, where they were subjected to comparison and geo-statistical analysis. A large number of sections perpendicular to the coast (every 100 meters) was drawn and the relative motion of the coastline was calcu-lated for each of them. The average rate of the calculated erosion is in the order of 24mm/year whilst extreme rates of 1m/year were also observed in specific posi-tions.
In tectonically active areas, such as in the northwest Peloponnese of western Greece, geomorphic processes are strongly influenced by active faulting; in many cases such faults cannot be easily identified. In this paper we apply multidisciplinary analysis (morphotectonic indices, neotectonic mapping, geophysical surveys and remote sensing techniques) to map the recently-recognized east–west trending Pineios River normal fault zone with a high degree of accuracy, and to better understand its contribution to the evolution of the ancient region of Elis during Holocene time. Fault activity seems to be related to frequent changes in river flow patterns and to displacements of the nearby shoreline. We argue that fault activity is the main reason for migration of Pineios river mouth as documented for several time periods during historical time. Quantitative constraints on deformation caused by the faulting were applied through the application of the morphotectonic indices proposed in this paper, including drainage network asymmetry and sinuosity, and mountain front sinuosity, all of which indicate that this is a highly active structure. Slip rates calculated to be as high as 0.48 mm/yr for the last 209 ka (based on previously published dating) were verified by applied geophysical methods. The fault surface discontinuity was identified at depth using vertical electrical resistivity measurements and depositional layers of different resistivity were found to be clearly offset. Displacement increases toward the west, reaching an observed maximum of 110 m. The most spectacular landform alteration due to surface deformation is the north–south migration of the river estuary into completely different open sea areas during the late Quaternary, mainly during the Holocene. The sediment transport path has been altered several times due to these changes in river geometry with and the most recent seeming to have occurred almost 2000 years ago. The river estuary migrated to its contemporary position along the southern coast, settled on the hanging wall, inducing retrograding of the northern coast, and settled on the foot wall, with rates reaching the order of 0.52 m/yr, as concluded from historical and recently-acquired remote sensing data.
The aim of the present study is to investigate the morphodynamic regime of the coastal area of Xylokastro (north coast of Peloponnese), in order to identify and evaluate the processes controlling its formation and evolution. Within this concept, a number of factors have been considered and evaluated; near-shore morphometry and granulometry along shore-normal profiles, the direction and potential volumes of long- and cross-shore sediment transport the decadal and future trends of coastline displacement, the available information for terrestrial sediment influx and the geological processes operating in the broader coastal region of Xylokastro (i.e. subaqueous slides) as well as human interference. On the basis of these results, the formation and evolution of this coastal stretch seems to be governed primarily by the neotectonic activity and relative change of sea level rise, and secondarily by the wave-induced near-shore sediment transport; the role of the latter could be enhanced substantially by human intervention (i.e. construction of marina, seafront walls). Moreover, the expected eustatic increase in sea level by the year 2100, could cause a coastline retreat up to 9 m (SLR=0.38 m) or >19 m (SLR≥1 m).
Although all five of the major mediterranean-climate ecosystems (MCEs) of the world are recognized as loci of high plant species diversity and endemism, they show considerable variation in regional-scale richness. Here, we assess the role of stable Pleistocene climate and Cenozoic topography in explaining variation in regional richness of the globe's MCEs. We hypothesize that older, more climatically stable MCEs would support more species, because they have had more time for species to accumulate than MCEs that were historically subject to greater topographic upheavals and fluctuating climates.
South-western Africa (Cape), south-western Australia, California, central Chile and the eastern (Greece) and western (Spain) Mediterranean Basin.
We estimated plant diversity for each MCE as the intercepts of species–area curves that are homogeneous in slope across all regions. We used two down-scaled global circulation models of the Last Glacial Maximum (LGM) to quantify climate stability by comparing the change in the location of MCEs between the LGM and present. We quantified the Cenozoic topographic stability of each MCE by comparing contemporary topographic profiles with those present in the late Oligocene and the early Pliocene.
The most diverse MCEs – Cape and Australia – had the highest Cenozoic environmental stability, and the least diverse – Chile and California – had the lowest stability.
Variation in plant diversity in MCEs is likely to be a consequence not of differences in diversification rates, but rather the persistence of numerous pre-Pliocene clades in the more stable MCEs. The extraordinary plant diversity of the Cape is a consequence of the combined effects of both mature and recent radiations, the latter associated with increased habitat heterogeneity produced by mild tectonic uplift in the Neogene.
A series of methodologies are described in this paper aiming to quantify the natural hazard due to the coastal changes at a deltaic fan. The coastline of Istiaia (North Evia, Greece) has been chosen for this study as several areas of accretion and erosion have been identified during the past few decades. We combined different types of datasets, extracted from high resolution panchromatic aerial photographs and traced the contemporary shoreline by high accuracy surveying with Real Time Kinematics (RTK) GPS equipment. The interpretation of all shorelines required geo-statistical analysis in a Geographical Information System. A large number of high resolution morphological sections were constructed normally to the coast, revealing erosional and depositional parts of the beach. Retreating and extension rates were calculated for each section reaching the values of 0.98 m/yr and 1.36 m/yr, respectively. The results proved to be very accurate, allowing us to expand the developed methodology by using more complete time-series of remote sensing datasets along with more frequent RTK-GPS surveying.
The Sparta Fault system is a major structure approximately 64 km long that bounds the eastern flank of the Taygetos Mountain front (2407 m) and shapes the present-day Sparta basin. It was activated in 464 B.C., devastating the city of Sparta. This fault is examined and described in terms of its geometry, segmentation, drainage pattern and post-glacial throw, emphasising how these parameters vary along strike. Qualitative analysis of long profile catchments shows a significant difference in longitudinal convexity between the central and both the south and north parts of the fault system, leading to the conclusion of varying uplift rate along strike. Catchments are sensitive in differential uplift as it is observed by the calculated differences of the steepness index ksn between the outer (ksn < 83) and central parts (121 < ksn < 138) of the Sparta Fault along strike the fault system. Based on fault throw-rates and the bedrock geology a seismic hazard map has been constructed that extracts a locality specific long-term earthquake recurrence record. Based on this map the town of Sparta would experience a destructive event similar to that in 464 B.C. approximately every 1792 ± 458 years. Since no other major earthquake M ~ 7.0 has been generated by this system since 464 B.C., a future event could be imminent. As a result, not only time-independent but also time-dependent probabilities, which incorporate the concept of the seismic cycle, have been calculated for the town of Sparta, showing a considerably higher time-dependent probability of 3.0 ± 1.5% over the next 30 years compared to the time-independent probability of 1.66%. Half of the hanging wall area of the Sparta Fault can experience intensities ≥ IX, but belongs to the lowest category of seismic risk of the national seismic building code. On view of these relatively high calculated probabilities, a reassessment of the building code might be necessary.
In this paper we present a combination of several near surface geophysical investigation techniques with high resolution remote sensing image interpretations, in order to define the groundwater flow paths and whether they can be affected by future seismic events. A seasonal spring (Amvrakia) located at the foot of Meteora pillars near the village of Kastraki (Greece) was chosen as a test site. The Meteora conglomeratic formations crop out throughout the study area and are characterized by large discontinuities caused by post Miocene till present tectonic deformation [Ferriere et al. 2011, Royden and Papanikolaou 2011]. A network of groundwater pathways has been developed above the impermeable marls underlying the conglomeratic strata. Our research aims to define these water pathways in order to investigate and understand the exact mechanism of the spring by mapping the exposed discontinuity network with classic field mapping and remote sensing image interpretation and define their underground continuity with theΒ contribution of near surface geophysical techniques. Five Very Low Frequency (VLF) profiles were conducted with different directions around the spring aiming to detect possible conductive zones in the conglomeratic formations that the study area consists of. Moreover, two Electrical Resistivity Tomography (ERT) sections of a total length of 140m were carried out parallel to the VLF profiles for cross-checking and verifying the geophysical information. Both techniques revealed important conductive zones (<200 Ohm m) within the conglomerate strata, which we interpret as discontinuities filled with water supplying the spring, which are quite vulnerable to displacements as the hydraulic connections between them might be easily disturbed after a future seismic event.
New paleomagnetic data from Early Miocene to Pliocene terrestrial sedimentary and volcanic rocks in Central Greece constrain the history of vertical-axis rotation along the central part of the western limb of the Aegean arc. The present-day pattern of rapid block rotation within a broad zone of distributed deformation linking the right-lateral North Anatolian and Kephalonia continental transform faults initiated after Early Pliocene time, resulting in a uniform clockwise rotation of 24.3Β±6.5Β° over a region >250 km long and >150 km wide encompassing Central Greece and the western Cycladic archipelago. Because the published paleomagnetic dataset requires clockwise rotations of >50Β° in Western Greece after βΌ17 Ma, while our measurements resolve no vertical-axis rotation of Central Greece between βΌ15 Ma and post-Early Pliocene time, a large part of the clockwise rotation of Western Greece must have occurred during the main period of contraction within the external thrust belt of the Ionian Zone between βΌ17 and βΌ15 Ma. Pliocene initiation of rapid clockwise rotation in Central and Western Greece reflects the development of the North Anatoliaβ€“Kephalonia Fault system within the previously extended Aegean Sea region, possibly in response to entry of dense oceanic lithosphere of the Ionian Sea into the Hellenic subduction zone and consequent accelerated slab rollback. The development of the Aegean geometric arc therefore occurred in two short-duration pulses characterized by rapid rotation and strong regional deformation.
Pineios River is the 3 rd longest river in Peloponnese and flows in Kyllini wider area which is located close to the Hellenic Arc-Trench system. This is one of the most seismically and tectonically active regions in Greece with a great number of changes in the morphogenetic events taking place during the neotectonic period, as well as the last 100 ky. Prior to the 18 th century A.D., the lower alluvial Pineios River flowed north of the Kyllini peninsula and into the Ionian Sea southwest of Kotichi Lagoon, but the river now flows southward into a deltaic swamp and dune region, burying a former lagoon-barrier coastal zone. From this, it becomes apparent that this river is not monotonous in appearance and therefore is not completely controlled by hydrology and hydraulics. In fact, the lower alluvial Pineios River has reacted to major geological controls, surface deformation and uplift movements caused by the activity of the recently mapped Pineios normal fault zone and salt tectonics in Kyllini peninsula resulting in the river flow diversion from north to south at completely different open sea areas. The effects of the geological, tectonic and neotectonic activity and the impact of the human presence and influence on the lower Pineios River are presented in this paper in order to determine the causes of the diversion of the lower (alluvial) Pineios River (NW Peloponnese, Greece) and shoreline displacements.
Rapid northeast-vergent subduction along the Hellenic trench, at ~ 35 mm/yr, exists in concert with widespread extensional and strike-slip faulting within the upper plate lithosphere of western Greece. Integration of regional geomorphic, geologic, seismic, GPS, remote sensing and field data demonstrates that young and active deformation in the area, extending from the Hellenic subduction boundary near Kephalonia to the Gulf of Corinth, consists of an interconnected network containing highly localized zones of deformation. These bound a series of crustal fragments with relatively little internal deformation. These deformation zones merge to form triple junction-like features at the western end of the Gulf of Corinth and in the Amvrakikos Gulf. At the western end of the Corinth Gulf, most of its 14 ± 2 mm/yr of extension is relayed to the northwest along a prominent zone of left-slip and extension through Lake Trichonis and the Amphilochia fault zone (11 ± 2 mm/yr). The remaining displacement across the western Gulf of Corinth is relayed into 7 ± 2 mm/yr of right-slip on the southwest-striking Achaia fault zone, which traverses the northwestern margin of the Peloponnesus. A second triple-junction like feature occurs in the Amvrakikos Basin, where the left-slip Amphilochia fault zone, the right-slip Kephalonia transform fault (15 ± 2 mm/yr) and the convergent thrust front of northern Hellenides (4 ± 2 mm/yr) are joined. Thus the extensional deformation in the Gulf of Corinth can be shown to be connected to convergence and subduction along the Hellenic trench through a series of discrete deformation zones that are not dissimilar from those observed in the global plate tectonic system.
The revised tectono-stratigraphy of Crete and especially of the "Phyllites-Quartzites" complex demonstrated the distinction of the probable Paleozoic low-medium grade metamorphic rocks of the Arna unit from the underlying Permo-Triassic phyllites and associated carbonate sediments (Trypali facies) of Western Crete unit as well as the overlying Permo-Triassic phyllites and associated sediments of the Tyros/Ravdoucha Beds at the base of the Tripolis unit. The pre-existing mixture of the above tectono-stratigaphic units in a single complex created a number of misinterpretations as far as stratigraphy, metamorphism and interpretation of low angle faults as thrusts or detachments. Especially in cases where the inferred tectonic contact concerns the transition between the Tyros Beds and the base of the Tripolis carbonate platform there is no structural omission and therefore the contact represents a minor disharmonic sliding surface and not a detachment. Based on the revised tectono-stratigraphic analysis the determination of the structural omission for each tectonic contact was possible and several detachments were described for the first time. Footwall rocks of the detachments comprised several tectonic units usually from the lower nappes and hanging wall rocks comprised several tectonic units usually from the upper nappes. The detachment may separate not only metamorphosed units in the footwall (Mani, Western Crete, Arna) from non metamorphosed units in the hanging wall (Tripolis, Pindos and higher nappes) but also all other possible combinations from the Cretan nappe pile. Extension in Crete started in the Middle-Late Miocene with the formation of extensional detachment faults. The reported extensional structures of Oligocene to Early Miocene age do not correspond to crustal extension of Crete but to localized shear zones related to nappe stacking and the exhumation of metamorphic rocks. Extensional detachments in Crete form a tectonic horst through two oppositely dipping E-W-trending zones; one dipping north, related to the opening of the Cretan basin, and the other dipping south, related to the formation of the Messara supra-detachment basin. The deformation history of units within Crete can be summarized as: (i) compressional deformation producing arc-parallel east-west-trending south-directed thrust faults in Oligocene to Early Miocene time; (ii) extensional deformation along arc-parallel, east-west-trending detachment faults in Middle Miocene time, with hanging wall motion to the north and south; and (iii) Late Miocene-Quaternary transtensional deformation along high-angle normal and oblique normal faults that disrupt the older arc-parallel structures.
Papanikolaou D, Vassilakis E, Valadaki K, Zacharias N, Maniatis I.
The city planning of Heraklion in Crete included the construction of the new Courthouse building at the eastern part of the town where several active fault have been mapped during an earlier microzonation study. The significance of the new building required detailed studies for the exact tracing of the faults and the period of their latest activation. The proposed methodology included trenching across the fault traces which are either controlling a morphological discontinuity or covered by human activities. Sampling for radiocarbon and optical luminance dating was carried out aiming for the exact age of the ruptured strata by the active faults. The combination of the described methodologies resulted the modification of the city plan, as constructions were designed to be built on the fault trace.
National and Kapodistrian University of Athens (+30) 210-7274400 Faculty of Geology & Geoenvironment Dpt of Geography & Climatology Panepistimiopolis, Zografou Athens, ZipCode 157-84 email@example.com