George Kaviris | National & Kapodistrian University of Athens (original) (raw)

Papers by George Kaviris

Research paper thumbnail of The Use of Innovative Techniques for Management of High-Risk Coastal Areas, Mitigation of Earthquake-Triggered Landslide Risk and Responsible Coastal Development

Applied Sciences, 2022

Coastal areas constitute a very dynamic environment, balancing between numerous natural and anthr... more Coastal areas constitute a very dynamic environment, balancing between numerous natural and anthropogenic processes liable to sometimes hazardous geomorphic phenomena. Especially in tectonically active coastal regions and areas of high economic value, slope failures can have significant impacts and therefore need careful and detailed examination. This work uses Unmanned Aerial System (UAS)-aided photogrammetry and Terrestrial Laser Scanning (TLS) in tectonically active segments of the coastal zone of the Ionian Islands in Greece, to explore how their capabilities can help to improve our understanding of the structural integrity of the slopes. Results show that the two approaches are able to extract large numbers of discontinuity facets, in a more practical, rapid and safe way than conventional methods of rock slope stability analysis extending to unreachable yet important parts of the slope. Through this holistic record of the structural condition of the slope the two applications a...

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Research paper thumbnail of Seismic anisotropy and shear-wave splitting: Achievements and perspectives: foreword

Annals of Geophysics, Jun 27, 2023

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Research paper thumbnail of A Logic-Tree Approach for Probabilistic Seismic Hazard Assessment in the Administrative Region of Attica (Greece)

Applied sciences, Jun 26, 2023

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Research paper thumbnail of On the origin of upper crustal shear-wave anisotropy at Samos Island, Greece

Acta Geophysica, May 11, 2021

Shear-wave splitting is associated to different sources in the upper crust. Preferentially orient... more Shear-wave splitting is associated to different sources in the upper crust. Preferentially oriented minerals, stress-aligned microcracks and tectonic structures have all been identified as causes of seismic anisotropy in the upper crust. However, distinguishing between them and discovering the actual origin of the splitting effect has important implications; changes in the anisotropic properties of the medium related to the behavior of fluid-filled microcracks could have potential connections to the occurrence of an impending significant earthquake. The recent 2020 Samos Mw = 6.9 event and its associated sequence was a great opportunity to study shear-wave splitting in the area. The spatial constrains in such studies, i.e., the requirement of events located very close to the receivers, did not permit exploring local anisotropy in the past, due to a severe lack of suitable data. To establish a background of splitting, we searched for any appropriate earthquake in a five-year period preceding the mainshock. We performed an automatic analysis on over 200 event-station pairs and obtained 164 high-quality splitting observations between January 2015 and November 2020. Results indicated a strong connection to local structures; Sfast polarization axes seem to align with faults in the area. However, we also observed a period of increasing and decreasing time-delays, associated with an Mw = 6.3 earthquake that occurred on June 2017 near Lesvos Island. The latter behavior implies the possibility of stress-induced anisotropy in the area. Thus, the Samos Island could be represented by two different sources of splitting; structures to the NW and microcracks to the SE.

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Research paper thumbnail of Earthquake Diffusion Variations in the Western Gulf of Corinth (Greece)

Pure and Applied Geophysics, Jun 10, 2021

Earthquake diffusion and the migration behaviour of seismic clusters are commonly studied to prov... more Earthquake diffusion and the migration behaviour of seismic clusters are commonly studied to provide insight on the spatiotemporal evolution of seismicity and the interplaying driving mechanisms. Using a high-resolution relocated catalogue, we study the variations of the earthquake diffusion rates in the Western Gulf of Corinth during 2013–2014, a period with abundant local seismicity, including intense microseismic background, seismic swarms and mainshock-aftershock sequences. We treat earthquake occurrence as a point process in time and space and estimate the diffusion rates of the main seismic sequences and the background seismicity in terms of normalized spatial histograms and the evolutions of the mean squared distance of seismicity with time. The statistical analysis of the studied seismic sequences reveals that the mean squared distance of the hypocentres increases slowly with time, at a much lower rate than for a normal diffusion process. Such findings confirm previous results on weak earthquake diffusion, analogous to subdiffusion, in regional and clustered seismicity. In addition, seismic swarms associated with pore fluid pressure diffusion present considerably higher diffusion exponents compared to mainshock-aftershock-type sequences that are consistent with primary or secondary stress triggering effects and stress corrosion. The observed variations of the earthquake diffusion rates indicate the stochastic nature of the phenomenon and may provide novel constraints on the triggering mechanisms of clustered seismic activity in the Western Gulf of Corinth and in other seismically active regions.

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Research paper thumbnail of Shear-wave splitting perspectives from the intense aftershock sequence of Damasi – Tyrnavos

Annals of Geophysics, May 5, 2023

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Research paper thumbnail of Shear-wave splitting properties of the upper crust, during the 2013–2014 seismic crisis, in the CO2-rich field of Florina Basin, Greece

Physics of the Earth and Planetary Interiors, Jun 1, 2020

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Research paper thumbnail of Near-Fault Broadband Ground Motion Simulation Applications at the Central Ionian Islands, Greece

Pure and Applied Geophysics, Jul 22, 2021

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Research paper thumbnail of Pytheas: An open-source software solution for local shear-wave splitting studies

Computers & Geosciences, 2020

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Research paper thumbnail of The 2020-2021 Seismic Swarm in the Western Gulf of Corinth: Insights on the Triggering Mechanisms Through High Resolution Seismological and Geodetic Data Analysis

SSRN Electronic Journal

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Research paper thumbnail of The CRL School in the European Education community and the modern classroom

<p>In the Gulf of Corinth area in Central Greece, for about 30 years, a concerted e... more <p>In the Gulf of Corinth area in Central Greece, for about 30 years, a concerted effort is being performed to better understand the Geophysical processes (Earthquakes, Landslides, Tsunamis) that take place. It is one of the narrowest and fastest extending continental regions worldwide and has one of the highest seismicity rates in the Euro-Mediterranean region.</p> <p>The area is studied by research teams from all over Europe and a network, the Corinth Rift Laboratory (<strong>C.R.L.</strong>), has been established. Aiming to perform the most complete and thorough studies, many instruments have been installed (~70 Seismometers, Accelerometers, GNSS satellite receivers, etc.). The Corinth Rift Laboratory (CRL) is a Near Fault Observatory (NFO) within the European Plate Observing Systems (EPOS).</p> <p>Since 2016, every year, the <em><strong>"School of the Corinth Rift Laboratory" (CRL School),</strong></em> the educational component of this natural Observatory, is being held in the CRL area with the support of <strong>EGU – GIFT</strong>, to educate Primary and Secondary Education Teachers and University Students in the ‘real’ research issues.</p> <p>The aims of the school are to:</p> <ul> <li>Bring the Research/University community in contact with Primary and Secondary Education Teachers to enrich their knowledge, with an impact on the most efficient and targeted education and its dissemination to students.</li> <li>Intensify osmosis and collaboration between Teachers from different schools in European countries.</li> <li>Be next to the on-site research and related activities carried out in the scientific fields of Seismology, Geophysics, Geodesy, Tectonics and Geology for the physical laboratory of CRL.</li> <li>To inspire Teachers for new actions and for new activities and tasks that they can assign to students.</li> <li>To encourage them to participate in international scientific conferences in specific thematic areas in education (such as E.G.U.)</li> </ul> <p>During the <strong>C.R.L. School</strong>, School Teachers participate in activities as:</p> <ul> <li>Introduction to Seismology, Geophysics, Geodesy, Tectonics and Geology, focused on the Gulf of Corinth through lectures, hands-on and field trips by Researchers, University Professors, Academic students and Primary –Secondary Education Teachers.</li> <li>Seismological, Geodetic and Geological measurements and visits to permanent operational stations.</li> <li>Hands-on for locating earthquakes in the Gulf of Corinth area using real waveform data.</li> <li>Operate and use special educational equipment for measuring and understanding seismic vibrations.</li> <li>Acquaintance with modern educational tools and methodology for the school classroom.</li> <li>Further analysis of measurements in student classes, in collaboration with C.R.L. partner schools and educators participating in C.R.L. and E.G.U..</li> <li>Earth Observation with emphasis on ground deformation measurements from satellite microwave radars and its application to C.R.L., with presentations and in the laboratory.</li> <li>Geohazards with emphasis on seismic hazard and implications in technical Geology, as the Rio - Antirrio Bridge case.</li> </ul> <p>Teachers' participation is completely free with a grant from E.G.U..</p>

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Research paper thumbnail of Near-Surface Geophysical Characterization of Lithologies in Corfu and Lefkada Towns (Ionian Islands, Greece)

Geosciences

Lefkada and Corfu old towns are located in the western part of Greece, in the Ionian Sea. Their p... more Lefkada and Corfu old towns are located in the western part of Greece, in the Ionian Sea. Their proximity to the Hellenic subduction zone (HSZ) is the reason for their intense seismicity. The main goal of this study was the estimation of the geotechnical characteristics of the subsurface, with the contribution of applied geophysical techniques. Therefore, seismic refraction tomography (SRT) and multichannel analysis of surface waves (MASW) were applied. A total of thirty-three (33) seismic and geoelectrical profiles were performed in both towns in order to evaluate the geotechnical characteristics of the subsurface formations. Additionally, subsurface resistivity distributions were investigated with the application of electrical resistivity tomography (ERT). Some important elastic moduli were calculated through the combination of estimated seismic wave velocities and laboratory density measurements. The horizontal distribution of seismic velocities and mechanical properties (σ, E, K...

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Research paper thumbnail of An Atypical Shallow Mw 5.3, 2021 Earthquake in the Western Corinth Rift (Greece)

Journal of Geophysical Research: Solid Earth

Moderate‐to‐large earthquakes in rifts may occur on leading boundary faults or inner antithetic f... more Moderate‐to‐large earthquakes in rifts may occur on leading boundary faults or inner antithetic faults. Here we show a rare case of the 2020–2021 seismic sequence in the Corinth rift, that culminated in the shallow rupture of the antithetic fault, neither preceded nor followed by the leading fault rupture. The hypocenter of the largest shock (Mw 5.3 of 17 February 2021) was located at ∼8 km depth. However, seismic waveform data, supported by satellite‐geodetic and tide gauge measurements, pointed to rupture at shallow depth (∼3 km), where no earthquakes were previously observed. We show that the earthquake most probably ruptured two orthogonal, conjugate fault segments: a weak nucleation phase occurred in the microseismically highly active sub‐horizontal detachment layer, followed – a few seconds later – by a larger, shallow moment release on a high‐angle, south‐dipping normal fault. The latter is the Mornos offshore fault, antithetic to the leading, north‐dipping Psathopyrgos fault...

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Research paper thumbnail of The 2020 Perachora peninsula earthquake sequence (Εast Corinth Rift, Greece): spatiotemporal evolution and implications for the triggering mechanism

Acta Geophysica

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Research paper thumbnail of The Near Fault Observatory community in Europe: a new resource for faulting and hazard studies

Annals of Geophysics

The Near Fault Observatories (NFOs) community is one of the European Plate Observing System (EPOS... more The Near Fault Observatories (NFOs) community is one of the European Plate Observing System (EPOS, http://www.epos-eu.org) Thematic Communities, today consisting of six research infrastructures that operate in regions characterised by high seismic hazard originating from different tectonic regimes. Earthquakes respond to complex natural systems whose mechanical properties evolve over time. Thus, in order to understand the multi-scale, physical/chemical processes responsible for the faulting that earthquakes occur on, it is required to consider phenomena that intersect different research fields, i.e., to put in place multidisciplinary monitoring. Hence, NFOs are grounded on modern and multidisciplinary infrastructures, collecting near fault high resolution raw data that allows generation of innovative scientific products. The NFOs usually complement regional backbone networks with a higher density distribution of seismic, geodetic, geochemical and other geophysical sensors, at surfac...

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Research paper thumbnail of The 27 September 2021 Earthquake in Central Crete (Greece)—Detailed Analysis of the Earthquake Sequence and Indications for Contemporary Arc-Parallel Extension to the Hellenic Arc

Applied Sciences

The Arkalochori village in central Crete was hit by a large earthquake (Mw = 6.0) on 27 September... more The Arkalochori village in central Crete was hit by a large earthquake (Mw = 6.0) on 27 September 2021, causing casualties, injuries, and severe damage to the infrastructure. Due to the absence of apparent surface rupture and the initial focal mechanism solution of the seismic event, we initiated complementary, multi-disciplinary research by combining seismological and remote sensing data processing, followed by extensive field validation. Detailed geological mapping, fault surface measuring accompanied with tectonic analysis, fault photorealistic model creation by unmanned aerial system data processing, post-seismic surface deformation analysis by DInSAR image interpretation coupled with accurately relocated epicenters recorded by locally established seismographs have been carried out. The combination of the results obtained from these techniques led to the determination of the contemporary tectonic stress regime that caused the earthquake in central Crete, which was found compatib...

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Research paper thumbnail of An integrated UAS and TLS approach for monitoring coastal scarps and mass movement phenomena. The case of Ionian Islands

<p>Mediterranean tectonically-active coastal areas are a highly-dynamic environment... more <p>Mediterranean tectonically-active coastal areas are a highly-dynamic environment balancing internal tectonic dynamics with external geomorphic processes, as well as manmade influences. Especially in touristic areas characterized by high built-up pressure and land value, where these dynamics are even more concentrated, the evolution of coastal environments needs careful and high-resolution study to identify localized risk and the processes they derive from.<br>Recently, new advanced remote sensing techniques such as Unmanned Aerial Systems (UAS)- and Terrestrial Laser Scanners (TLS)-aided monitoring have improved our capabilities in understanding the natural processes and the geomorphic risks (i.e. mass movement phenomena).<br>An integrated study comprising Unmanned Aerial Vehicles (UAV) and Light Detection And Ranging (LIDAR) sensors was conducted in coastal areas of the southern Ionian Islands (Western Greece) aiming to the mitigation of earthquake-triggered landslide risk and to responsible coastal development. Located at the northwesternmost part of the Hellenic Arc, this area is characterized by high seismicity and has been affected by destructive earthquakes mainly due to the Cephalonia Transform Fault Zone (CTFZ), which constitutes one of the most seismic active structures in the Eastern Mediterranean region. One of the most common environmental effect triggered by these earthquakes are landslides distributed along fault scarps in developed and highly visited coastal areas. Furthermore, this area is highly susceptible to hydrometeorological hazards inducing intense geomorphic processes, including Medicanes among others.<br>These technologies allow a highly-detailed view of landslide processes, providing insights on the structures and factors controlling and triggering failures along coastal scarps as well as highlighting susceptible zones and high-risk areas with accuracy and mitigating adverse effects with precision and clarity. Overall, by providing a better understanding of the risks the approach used allows a more sustainable development of these coastal segments enhanced by risk mitigation.<br>The study was conducted in the framework of the project “Telemachus - Innovative Operational Seismic Risk Management System of the Ionian Islands”, co-financed by Greece and the European Union (European Regional Development Fund) in Priority Axis “Environmental Protection and Sustainable Development” of the Operational Programme “Ionian Islands 2014–2020”.</p>

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Research paper thumbnail of The 19 July 2019 earthquake in Athens, Greece: A delayed major aftershock of the 1999 Mw = 6.0 event, or the activation of a different structure?

Journal of Geodynamics, 2020

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Research paper thumbnail of The scaling of PGA with IV2p and its potential for Earthquake Early Warning in Thessaly (Central Greece)

Bulletin of the Geological Society of Greece, Sep 13, 2021

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Research paper thumbnail of Correction to: On the origin of upper crustal hear‑wave anisotropy at Samos Island, Greece

Acta Geophysica, May 31, 2021

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Research paper thumbnail of The Use of Innovative Techniques for Management of High-Risk Coastal Areas, Mitigation of Earthquake-Triggered Landslide Risk and Responsible Coastal Development

Applied Sciences, 2022

Coastal areas constitute a very dynamic environment, balancing between numerous natural and anthr... more Coastal areas constitute a very dynamic environment, balancing between numerous natural and anthropogenic processes liable to sometimes hazardous geomorphic phenomena. Especially in tectonically active coastal regions and areas of high economic value, slope failures can have significant impacts and therefore need careful and detailed examination. This work uses Unmanned Aerial System (UAS)-aided photogrammetry and Terrestrial Laser Scanning (TLS) in tectonically active segments of the coastal zone of the Ionian Islands in Greece, to explore how their capabilities can help to improve our understanding of the structural integrity of the slopes. Results show that the two approaches are able to extract large numbers of discontinuity facets, in a more practical, rapid and safe way than conventional methods of rock slope stability analysis extending to unreachable yet important parts of the slope. Through this holistic record of the structural condition of the slope the two applications a...

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Research paper thumbnail of Seismic anisotropy and shear-wave splitting: Achievements and perspectives: foreword

Annals of Geophysics, Jun 27, 2023

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Research paper thumbnail of A Logic-Tree Approach for Probabilistic Seismic Hazard Assessment in the Administrative Region of Attica (Greece)

Applied sciences, Jun 26, 2023

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Research paper thumbnail of On the origin of upper crustal shear-wave anisotropy at Samos Island, Greece

Acta Geophysica, May 11, 2021

Shear-wave splitting is associated to different sources in the upper crust. Preferentially orient... more Shear-wave splitting is associated to different sources in the upper crust. Preferentially oriented minerals, stress-aligned microcracks and tectonic structures have all been identified as causes of seismic anisotropy in the upper crust. However, distinguishing between them and discovering the actual origin of the splitting effect has important implications; changes in the anisotropic properties of the medium related to the behavior of fluid-filled microcracks could have potential connections to the occurrence of an impending significant earthquake. The recent 2020 Samos Mw = 6.9 event and its associated sequence was a great opportunity to study shear-wave splitting in the area. The spatial constrains in such studies, i.e., the requirement of events located very close to the receivers, did not permit exploring local anisotropy in the past, due to a severe lack of suitable data. To establish a background of splitting, we searched for any appropriate earthquake in a five-year period preceding the mainshock. We performed an automatic analysis on over 200 event-station pairs and obtained 164 high-quality splitting observations between January 2015 and November 2020. Results indicated a strong connection to local structures; Sfast polarization axes seem to align with faults in the area. However, we also observed a period of increasing and decreasing time-delays, associated with an Mw = 6.3 earthquake that occurred on June 2017 near Lesvos Island. The latter behavior implies the possibility of stress-induced anisotropy in the area. Thus, the Samos Island could be represented by two different sources of splitting; structures to the NW and microcracks to the SE.

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Research paper thumbnail of Earthquake Diffusion Variations in the Western Gulf of Corinth (Greece)

Pure and Applied Geophysics, Jun 10, 2021

Earthquake diffusion and the migration behaviour of seismic clusters are commonly studied to prov... more Earthquake diffusion and the migration behaviour of seismic clusters are commonly studied to provide insight on the spatiotemporal evolution of seismicity and the interplaying driving mechanisms. Using a high-resolution relocated catalogue, we study the variations of the earthquake diffusion rates in the Western Gulf of Corinth during 2013–2014, a period with abundant local seismicity, including intense microseismic background, seismic swarms and mainshock-aftershock sequences. We treat earthquake occurrence as a point process in time and space and estimate the diffusion rates of the main seismic sequences and the background seismicity in terms of normalized spatial histograms and the evolutions of the mean squared distance of seismicity with time. The statistical analysis of the studied seismic sequences reveals that the mean squared distance of the hypocentres increases slowly with time, at a much lower rate than for a normal diffusion process. Such findings confirm previous results on weak earthquake diffusion, analogous to subdiffusion, in regional and clustered seismicity. In addition, seismic swarms associated with pore fluid pressure diffusion present considerably higher diffusion exponents compared to mainshock-aftershock-type sequences that are consistent with primary or secondary stress triggering effects and stress corrosion. The observed variations of the earthquake diffusion rates indicate the stochastic nature of the phenomenon and may provide novel constraints on the triggering mechanisms of clustered seismic activity in the Western Gulf of Corinth and in other seismically active regions.

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Research paper thumbnail of Shear-wave splitting perspectives from the intense aftershock sequence of Damasi – Tyrnavos

Annals of Geophysics, May 5, 2023

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Research paper thumbnail of Shear-wave splitting properties of the upper crust, during the 2013–2014 seismic crisis, in the CO2-rich field of Florina Basin, Greece

Physics of the Earth and Planetary Interiors, Jun 1, 2020

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Research paper thumbnail of Near-Fault Broadband Ground Motion Simulation Applications at the Central Ionian Islands, Greece

Pure and Applied Geophysics, Jul 22, 2021

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Research paper thumbnail of Pytheas: An open-source software solution for local shear-wave splitting studies

Computers & Geosciences, 2020

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Research paper thumbnail of The 2020-2021 Seismic Swarm in the Western Gulf of Corinth: Insights on the Triggering Mechanisms Through High Resolution Seismological and Geodetic Data Analysis

SSRN Electronic Journal

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Research paper thumbnail of The CRL School in the European Education community and the modern classroom

<p>In the Gulf of Corinth area in Central Greece, for about 30 years, a concerted e... more <p>In the Gulf of Corinth area in Central Greece, for about 30 years, a concerted effort is being performed to better understand the Geophysical processes (Earthquakes, Landslides, Tsunamis) that take place. It is one of the narrowest and fastest extending continental regions worldwide and has one of the highest seismicity rates in the Euro-Mediterranean region.</p> <p>The area is studied by research teams from all over Europe and a network, the Corinth Rift Laboratory (<strong>C.R.L.</strong>), has been established. Aiming to perform the most complete and thorough studies, many instruments have been installed (~70 Seismometers, Accelerometers, GNSS satellite receivers, etc.). The Corinth Rift Laboratory (CRL) is a Near Fault Observatory (NFO) within the European Plate Observing Systems (EPOS).</p> <p>Since 2016, every year, the <em><strong>"School of the Corinth Rift Laboratory" (CRL School),</strong></em> the educational component of this natural Observatory, is being held in the CRL area with the support of <strong>EGU – GIFT</strong>, to educate Primary and Secondary Education Teachers and University Students in the ‘real’ research issues.</p> <p>The aims of the school are to:</p> <ul> <li>Bring the Research/University community in contact with Primary and Secondary Education Teachers to enrich their knowledge, with an impact on the most efficient and targeted education and its dissemination to students.</li> <li>Intensify osmosis and collaboration between Teachers from different schools in European countries.</li> <li>Be next to the on-site research and related activities carried out in the scientific fields of Seismology, Geophysics, Geodesy, Tectonics and Geology for the physical laboratory of CRL.</li> <li>To inspire Teachers for new actions and for new activities and tasks that they can assign to students.</li> <li>To encourage them to participate in international scientific conferences in specific thematic areas in education (such as E.G.U.)</li> </ul> <p>During the <strong>C.R.L. School</strong>, School Teachers participate in activities as:</p> <ul> <li>Introduction to Seismology, Geophysics, Geodesy, Tectonics and Geology, focused on the Gulf of Corinth through lectures, hands-on and field trips by Researchers, University Professors, Academic students and Primary –Secondary Education Teachers.</li> <li>Seismological, Geodetic and Geological measurements and visits to permanent operational stations.</li> <li>Hands-on for locating earthquakes in the Gulf of Corinth area using real waveform data.</li> <li>Operate and use special educational equipment for measuring and understanding seismic vibrations.</li> <li>Acquaintance with modern educational tools and methodology for the school classroom.</li> <li>Further analysis of measurements in student classes, in collaboration with C.R.L. partner schools and educators participating in C.R.L. and E.G.U..</li> <li>Earth Observation with emphasis on ground deformation measurements from satellite microwave radars and its application to C.R.L., with presentations and in the laboratory.</li> <li>Geohazards with emphasis on seismic hazard and implications in technical Geology, as the Rio - Antirrio Bridge case.</li> </ul> <p>Teachers' participation is completely free with a grant from E.G.U..</p>

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Research paper thumbnail of Near-Surface Geophysical Characterization of Lithologies in Corfu and Lefkada Towns (Ionian Islands, Greece)

Geosciences

Lefkada and Corfu old towns are located in the western part of Greece, in the Ionian Sea. Their p... more Lefkada and Corfu old towns are located in the western part of Greece, in the Ionian Sea. Their proximity to the Hellenic subduction zone (HSZ) is the reason for their intense seismicity. The main goal of this study was the estimation of the geotechnical characteristics of the subsurface, with the contribution of applied geophysical techniques. Therefore, seismic refraction tomography (SRT) and multichannel analysis of surface waves (MASW) were applied. A total of thirty-three (33) seismic and geoelectrical profiles were performed in both towns in order to evaluate the geotechnical characteristics of the subsurface formations. Additionally, subsurface resistivity distributions were investigated with the application of electrical resistivity tomography (ERT). Some important elastic moduli were calculated through the combination of estimated seismic wave velocities and laboratory density measurements. The horizontal distribution of seismic velocities and mechanical properties (σ, E, K...

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Research paper thumbnail of An Atypical Shallow Mw 5.3, 2021 Earthquake in the Western Corinth Rift (Greece)

Journal of Geophysical Research: Solid Earth

Moderate‐to‐large earthquakes in rifts may occur on leading boundary faults or inner antithetic f... more Moderate‐to‐large earthquakes in rifts may occur on leading boundary faults or inner antithetic faults. Here we show a rare case of the 2020–2021 seismic sequence in the Corinth rift, that culminated in the shallow rupture of the antithetic fault, neither preceded nor followed by the leading fault rupture. The hypocenter of the largest shock (Mw 5.3 of 17 February 2021) was located at ∼8 km depth. However, seismic waveform data, supported by satellite‐geodetic and tide gauge measurements, pointed to rupture at shallow depth (∼3 km), where no earthquakes were previously observed. We show that the earthquake most probably ruptured two orthogonal, conjugate fault segments: a weak nucleation phase occurred in the microseismically highly active sub‐horizontal detachment layer, followed – a few seconds later – by a larger, shallow moment release on a high‐angle, south‐dipping normal fault. The latter is the Mornos offshore fault, antithetic to the leading, north‐dipping Psathopyrgos fault...

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Research paper thumbnail of The 2020 Perachora peninsula earthquake sequence (Εast Corinth Rift, Greece): spatiotemporal evolution and implications for the triggering mechanism

Acta Geophysica

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Research paper thumbnail of The Near Fault Observatory community in Europe: a new resource for faulting and hazard studies

Annals of Geophysics

The Near Fault Observatories (NFOs) community is one of the European Plate Observing System (EPOS... more The Near Fault Observatories (NFOs) community is one of the European Plate Observing System (EPOS, http://www.epos-eu.org) Thematic Communities, today consisting of six research infrastructures that operate in regions characterised by high seismic hazard originating from different tectonic regimes. Earthquakes respond to complex natural systems whose mechanical properties evolve over time. Thus, in order to understand the multi-scale, physical/chemical processes responsible for the faulting that earthquakes occur on, it is required to consider phenomena that intersect different research fields, i.e., to put in place multidisciplinary monitoring. Hence, NFOs are grounded on modern and multidisciplinary infrastructures, collecting near fault high resolution raw data that allows generation of innovative scientific products. The NFOs usually complement regional backbone networks with a higher density distribution of seismic, geodetic, geochemical and other geophysical sensors, at surfac...

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Research paper thumbnail of The 27 September 2021 Earthquake in Central Crete (Greece)—Detailed Analysis of the Earthquake Sequence and Indications for Contemporary Arc-Parallel Extension to the Hellenic Arc

Applied Sciences

The Arkalochori village in central Crete was hit by a large earthquake (Mw = 6.0) on 27 September... more The Arkalochori village in central Crete was hit by a large earthquake (Mw = 6.0) on 27 September 2021, causing casualties, injuries, and severe damage to the infrastructure. Due to the absence of apparent surface rupture and the initial focal mechanism solution of the seismic event, we initiated complementary, multi-disciplinary research by combining seismological and remote sensing data processing, followed by extensive field validation. Detailed geological mapping, fault surface measuring accompanied with tectonic analysis, fault photorealistic model creation by unmanned aerial system data processing, post-seismic surface deformation analysis by DInSAR image interpretation coupled with accurately relocated epicenters recorded by locally established seismographs have been carried out. The combination of the results obtained from these techniques led to the determination of the contemporary tectonic stress regime that caused the earthquake in central Crete, which was found compatib...

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Research paper thumbnail of An integrated UAS and TLS approach for monitoring coastal scarps and mass movement phenomena. The case of Ionian Islands

<p>Mediterranean tectonically-active coastal areas are a highly-dynamic environment... more <p>Mediterranean tectonically-active coastal areas are a highly-dynamic environment balancing internal tectonic dynamics with external geomorphic processes, as well as manmade influences. Especially in touristic areas characterized by high built-up pressure and land value, where these dynamics are even more concentrated, the evolution of coastal environments needs careful and high-resolution study to identify localized risk and the processes they derive from.<br>Recently, new advanced remote sensing techniques such as Unmanned Aerial Systems (UAS)- and Terrestrial Laser Scanners (TLS)-aided monitoring have improved our capabilities in understanding the natural processes and the geomorphic risks (i.e. mass movement phenomena).<br>An integrated study comprising Unmanned Aerial Vehicles (UAV) and Light Detection And Ranging (LIDAR) sensors was conducted in coastal areas of the southern Ionian Islands (Western Greece) aiming to the mitigation of earthquake-triggered landslide risk and to responsible coastal development. Located at the northwesternmost part of the Hellenic Arc, this area is characterized by high seismicity and has been affected by destructive earthquakes mainly due to the Cephalonia Transform Fault Zone (CTFZ), which constitutes one of the most seismic active structures in the Eastern Mediterranean region. One of the most common environmental effect triggered by these earthquakes are landslides distributed along fault scarps in developed and highly visited coastal areas. Furthermore, this area is highly susceptible to hydrometeorological hazards inducing intense geomorphic processes, including Medicanes among others.<br>These technologies allow a highly-detailed view of landslide processes, providing insights on the structures and factors controlling and triggering failures along coastal scarps as well as highlighting susceptible zones and high-risk areas with accuracy and mitigating adverse effects with precision and clarity. Overall, by providing a better understanding of the risks the approach used allows a more sustainable development of these coastal segments enhanced by risk mitigation.<br>The study was conducted in the framework of the project “Telemachus - Innovative Operational Seismic Risk Management System of the Ionian Islands”, co-financed by Greece and the European Union (European Regional Development Fund) in Priority Axis “Environmental Protection and Sustainable Development” of the Operational Programme “Ionian Islands 2014–2020”.</p>

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Research paper thumbnail of The 19 July 2019 earthquake in Athens, Greece: A delayed major aftershock of the 1999 Mw = 6.0 event, or the activation of a different structure?

Journal of Geodynamics, 2020

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The scaling of PGA with IV2p and its potential for Earthquake Early Warning in Thessaly (Central Greece)

Bulletin of the Geological Society of Greece, Sep 13, 2021

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Correction to: On the origin of upper crustal hear‑wave anisotropy at Samos Island, Greece

Acta Geophysica, May 31, 2021

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