George Kaviris

National and Kapodistrian University of Athens | uoa · Department of Geophysics and Geothermics

The Central Ionian Islands of Cephalonia and Ithaca belong to the most seismically active Greek region, mainly due to the presence of the dextral Cephalonia-Lefkada Transform Fault Zone. The study area has experienced strong earthquakes in the twentieth century, including the destructive 1953 sequence with maximum intensity 9.0. The Paliki peninsul...

The co-seismic and post-seismic deformation field associated with the Mw5.9 Arkalochori main shock that occurred in central Crete (Greece) on 27 September 2021 is analyzed using Copernicus Sentinel-1 A & 1B images, GNSS measurements and seismological data. The fault geometry is constrained through the joint inversion of multiple datasets and the sl...

The intense and persistent seismic activity in the Island of Euboea (or Evia) was a unique opportunity to study anisotropy in region without any notable prior seismicity. The study area is located in the central-western Aegean Sea and constitutes the endpoint of a series of geotectonic units that feature dextral strike-slip faulting, such as the No...

The Central Ionian Islands of Cephalonia and Ithaca belong to the most seismically active Greek region, mainly due to the presence of the dextral Cephalonia-Lefkada Transform Fault Zone. The study area has experienced strong earthquakes in the 20 th century, including the destructive 1953 sequence with maximum intensity 9.0. The Paliki peninsula, w...

An earthquake swarm occurred during 2020-2021 at the Perachora peninsula, situated at the eastern part of the Gulf of Corinth (Greece), one of the most seismically active areas in Europe. In this work, we analyzed the swarm using a high-resolution earthquake catalog and advanced processing techniques. We employed both single-station and multi-chann...

Reduction of the impact of natural hazards and enhancement of the resilience of population involves access to straightforward information about safe and non-safe areas during the occurrence of a natural phenomenon. The present study focusses on the drainage basin of the Xerias River, at northeastern Peloponnese, Greece, an area highly prone to floo...

This special issue of Annals of Geophysics “Seismic anisotropy and shear-wave splitting: Achievements and perspectives” originates from a session (S10) of the 37th General assembly of the European Seismological commission ESC 2021 Conference which was planned to take place on 21 September 2021, in Corfu Greece, but due to the Covid19 pandemic was V...

Probabilistic Seismic Hazard Assessment (PSHA) was carried out for the administrative region of Attica (Greece). Peak Ground Acceleration (PGA) and Peak Ground Velocity (PGV) values were calculated for return periods of 475 and 950 years for five sub-areas covering the entire region. PGA hazard curves and Uniform Hazard Spectra (UHS) in terms of sp...

The Eastern Gulf of Corinth (EGoC) is one of the most seismically active areas in Greece. It is monitored by local and regional seismic stations of the Hellenic Unified Seismic Network (HUSN). In 2020, a high-yield seismic sequence, lasting over five months, occurred at the Perachora peninsula. This provided a unique opportunity to investigate the...

The area of Damasi-Tyrnavos (Thessaloniki, Central Greece), in the vicinity of Larissa, was characterized by low seismic activity during the last decades. Two strong earthquakes of Mw = 6.3 and Mw = 6.0 The area of Damasi – Tyrnavos (Thessaly, Central Greece), in the vicinity of Larissa, was characterized occurred in early March 2021, followed by a...

The Athenet network is the network of the Seismological Laboratory of the National and Kapodistrian University of Athens. We present the geophysical investigation that has been carried out at six seismological stations of the Athenet network for their site characterization. More specifically, at the location of each seismological station, four geop...

The Corinth Rift, in Central Greece, is one of the most seismically active areas in Europe. In the eastern part of the Gulf of Corinth, which has been the site of numerous large and destructive earthquakes in both historic and modern times, a pronounced earthquake swarm occurred in 2020-2021 at the Perachora peninsula. Herein, we present an in-dept...

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. The...

The Gulf of Corinth (Central Greece) is one of the most rapidly extending rifts worldwide, with its western part being the most seismically active, hosting numerous strong (M ≥ 6.0) earthquakes that have caused significant damage. The main objective of this study was the evaluation of seismic hazard through a probabilistic and stochastic methodolog...

Seismicity accompanied with intense ground deformation in the Ionian Sea (W. Greece) is mainly generated along the Cephalonia-Lefkada Transform Fault Zone (CLTFZ), in the central Ionian, and on the northwestern termination of the Hellenic subduction margin in the south. Pre- co- and post-seismic ground deformation analysis is performed at the broad...

Investigation of the subsurface structure of Lefkada town using a multidisciplinary geophysical approach. In this paper we present the preliminary results of a near-surface geophysical research carried out on Lefkada island, for the investigation of the geological setting of Lefkada town. The geophysical survey has also been extended in selected lo...

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....

A Mw=4.6 event occurred on 2 December 2020 east of Thiva, a major town at the eastern part of Boeotia, located in Central Greece, followed by a seismic swarm during July-October, at the town and its surroundings, which included three Mw>4.0 events. The southern part of Boeotia is affected by the high seismicity of the Gulf of Corinth, which has an...

Attica region (Central Greece), which hosts over three million residents, has experienced strong earthquakes. The most destructive event of the instrumental era is the 7 September 1999 Athens earthquake that caused damage in structures and many fatalities. After 20 years, the 19 July Mw=5.1 event occurred near the 1999 epicenter. In addition, Attic...

A destructive Mw=6.0 earthquake occurred on 7 September 1999 in Western Attica, in the vicinity of Athens, causing 143 fatalities and hundreds of injuries. The analysis of the aftershocks revealed the existence of the shear-wave splitting phenomenon, indicative of seismic anisotropy in the upper crust. Mean time-delays between the two split shear-w...

Strong crustal earthquakes in Greece are typically followed by aftershocks, the properties of which are important factors in seismic hazard assessment. In order to examine the properties of earthquake sequences, we prepared an earthquake catalog comprising aftershock sequences with mainshocks of Mw ≥ 5.5 from 1995 to 2021. Regional aftershock param...

In this work, we study the January 1, 2020 – June 8, 2021, earthquake activity in the East Corinth Rift (central Greece), one of the most seismically active areas in Europe. During this period an intense earthquake sequence occurred in the Perachora peninsula, presenting the characteristics of swarm activity. We present a relocated earthquake catal...

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 who...

In 2020, a pronounced earthquake sequence occurred at the Perachora peninsula, at the eastern edge of the active continental Corinth Rift (Greece). The sequence evolved as a swarm over the course of four months, with the largest magnitude event (M w =3.7) occurring approximately 2 months after its initiation. The sequence was widely felt by the loc...

Transnational access (TNA) allows cross-border, short-term and frequently free-of-charge access to world-class research facilities, to foster collaborations and exchanges of experience. Specifically, TNA aims to encourage open science and innovation and to increase the efficient and effective use of scientific infrastructure. Within EPOS, the Europ...

Cephalonia, located in the middle of the central Ionian Islands, has been affected by destructive earthquakes during both the instrumental and the historical period. Despite the fact that it is widely studied from several scientific viewpoints, limited research has been conducted so far regarding the earthquake-triggered landslides (ETL) and the re...

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 combin...

We investigate an earthquake sequence involving an Mw = 4.6 mainshock on 2 December 2020, followed by a seismic swarm in July–October 2021 near Thiva, Central Greece, to identify the activated structures and understand its triggering mechanisms. For this purpose, we employ double-difference relocation to construct a high-resolution earthquake catal...

Seismicity in the Ionian Sea (W. Greece) is mainly generated along the Cephalonia–Lefkada Transform Fault Zone (CLTFZ) in the central Ionian, and on the northwestern termination of the Hellenic subduction margin in the south. Joint pre-, co- and post-seismic ground deformation and seismological analysis is performed at the broad Ionian area, aiming...

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. T...

Messinia is located in SW Peloponnese (Greece), in the vicinity of the Hellenic Arc which is one of the most seismically active areas of Europe. The arc is dominated by reverse faulting, whereas normal faults are mapped onshore, mainly striking N–S. Large earthquakes have occurred in the study area, both in the historical and instrumental periods....

In early March 2021, three shallow earthquakes, two mainshocks with M6.3 and M6.0 and one major aftershock with M5.6 impacted both the mountainous Damasi-Tyrnavos region (northern Thessaly, Greece) and the adjacent Plio-Quaternary basin. Each major event was followed by rich aftershock activity recorded by local and regional seismographs and accele...

The Western Gulf of Corinth (WGoC), Central Greece, is one of the fastest expanding continental rifts in the world and a closely monitored site of high geophysical interest. In this work, we employ data from the Corinth Rift Laboratory network and the Hellenic Unified Seismological Network to investigate the anisotropic properties of the upper crus...

The region of Messinia is located in SW Peloponnese (Greece), in the vicinity of the Hellenic Arc which is dominated by reverse faulting. The arc is one of the most seismically active areas of Europe. Normal faults are also mapped on land, mainly striking N-S, adding further complexities to the involved seismotectonic processes. The Mw=6.8 2008 Met...

Main scope of the “Telemachus” project is the creation of an innovative seismic risk management system for the Ionian Islands, the most seismically and tectonically active area in Greece and one of the most active worldwide. Seismic risk assessment and vulnerability studies will inform the decision-making system that will operate in GIS environment...

In the present study 380 seismic events were located in the Bransfield Strait area, which is a rift where active extension is ongoing, located in the Antarctic Ocean, between the South Shetland Islands and the Antarctic Peninsula. The Strait is approximately 120 km wide and 500 km long with a maximum depth of 2 km. The events were recorded during 2...

The physics behind aftershock generation remain a critical issue in the scientific community with different underlying mechanisms proposed to interpret the seismological observations. The spatial distribution of aftershocks has been traditionally used to constrain the dimensions of the ruptured fault after the mainshock occurrence, whereas it has b...

In the past 20 years, the Corinth Rift Laboratory (CRL) network has been closely monitoring the Western Gulf of Corinth (WGoC), the area being the main focus of the Corinth Rift Near Fault Observatory. The local seismological and geodetic network permitted the detection and location of microseismicity in high resolution, revealing complex sequences...

The Western Gulf of Corinth (WGoC), Central Greece, is one of the fastest expanding continental rifts in the world and a closely monitored site of high geophysical interest. In this work, we employ data from the Corinth Rift Laboratory network and the Hellenic Unified Seismological Network to investigate the anisotropic properties of the upper crus...

The tectonic evolution of the southeastern Tibetan Plateau is key to understanding the mechanism of growth of the whole Tibetan Plateau. Its imprint on lithospheric and asthenospheric mantle rock fabrics is expected to have a strong signature on seismic anisotropy. In this study, we measure the splitting delays and fast polarization directions (FPD...

The main goal of an Earthquake Early Warning System (EEWS) is to estimate the expected peak ground motion of the destructive S-waves using the first few seconds of P-waves, thus becoming an operational tool for real-time seismic risk management in a short timescale. EEWSs are based on the use of scaling relations between parameters measured on the...

Physics-based broadband ground-motion simulations are generated for the strong mainshocks that occurred in the region of the Central Ionian Islands, on 26th January 2014 in Kefalonia (Mw6.1) and 17th November 2015 in Lefkas (Mw6.5). The study area is associated with frequent strong earthquakes both in the historical and instrumental era. During the...

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...

The broader area of Pournari dam (Western Greece) is investigated regarding the potential seismic hazard change after its impoundment in the early 1980’s. During this impoundment, an increase in local earthquake activity with certain features of induced seismicity was observed. Within the third and fourth month after the first filling, two moderate...

The Western Gulf of Corinth (WGoC) exhibits significant seismicity patterns, combining intense microseismic background activity with both seismic swarms and short-lived aftershock sequences. Herein, we present a catalogue of ~9000 events, derived by manual analysis and double-difference relocation, for the seismicity of the WGoC during 2013–2014. T...

We investigate a seismic crisis that occurred in the western Gulf of Corinth (Greece) between December 2020 and February 2021. This area is the main focus of the Corinth Rift Laboratory (CRL) network, and has been closely monitored with local seismological and geodetic networks for 20 yr. The 2020–2021 seismic crisis evolved in three stages: It sta...

On 2 December 2020, a moderate and shallow Mw = 4.6 earthquake occurred in Boeotia (Central Greece) near the city of Thiva. Despite its magnitude, the co-seismic ground deformation field was detectable and measurable by Sentinel-1, ascending and descending, synthetic aperture interferometry radar (InSAR) acquisitions. The closest available GNSS sta...

The present study aims to suggest an approach that allows the simultaneous hazard zonation mapping of earthquake-induced secondary effects. The modeling process of the applied methodology involves an initial separate evaluation of the hazard imposed by seismically induced landslides and soil liquefaction and a subsequent stacking into one single ha...

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 imp...

Earthquake diffusion is frequently observed in the spatiotemporal evolution of seismic clusters and regional seismicity, a characteristic that is attributed to a triggering mechanism, such as fluid flow, aseismic creep and/or stress transfer effects. In this work, we study the earthquake diffusion properties in the Western Gulf of Corinth (central...

A correction to this paper has been published: https://doi.org/10.1007/s11600-021-00613-6

The properties of the Mw=6.7 earthquake that took place on 25 October 2018, 22:54:51 UTC, ~50 km SW of the Zakynthos Island, Greece, are thoroughly examined. The main rupture occurred on a dextral strike-slip, low-angle, east-dipping fault at a depth of 12 km, as determined by teleseismic waveform modelling. Over 4000 aftershocks were manually anal...

The National Observatory of Athens data center for the European Integrated Data Archive (EIDA@NOA) is the national and regional node that supports International Federation of Digital Seismograph Networks and related webservices for seismic waveform data coming from the southeastern Mediterranean and the Balkans. At present, it serves data from eigh...

On 30 October 2020 11:51 UTC, a Mw=6.9 earthquake struck the offshore region north of Samos Island, Greece, in the Gulf of Ephesos/Kuşadasi, causing two fatalities and 19 minor injuries at Samos Island, as well as 115 casualties and over 1,030 injuries in Western Turkey. Preliminary results indicate that the mainshock occurred on a north-dipping no...

Earthquakes, large or even moderate, are often followed by secondary phenomena, such as landslides, tsunamis, fires and technological disasters, leading to cascading effects that may, in turn, cause severe repercussions. Before, during and after the occurrence of these events, risk communication, currently evolved to codified legislation, is a cruc...