Sotirios Valkaniotis

Democritus University of Thrace | DUTH · Department of Civil Engineering

On November 17, 2015 a strong, shallow earthquake (Mw = 6.5) occurred on the island of Lefkada along a N20 ± 5°E, east-dipping strike-slip fault with right-lateral sense of slip. The event triggered environmental effects that were mainly mapped at the western part of the island while moving towards the eastern part, the severity of the earthquake-i...

With the release of new Sentinel-2 images, and other available resources for the M7.8 Kaikoura earthquake, we present an update of the Map of Co-Seismic Landslides and Surfaces Ruptures (As of 27/11/2016). Landslides were mapped using Sentinel-2 satellite images from Copernicus, European Space Agency, dated 15,22 and 25 November 2016. Images were...

The Delphi‐Amfissa fault zone (DAFZ) is a large extensional structure north of the Corinth rift in central Greece. The DAFZ is associated with significant landscape features with evidence of post LGM activity and strong historical earthquakes. Large landslides along the Delphi fault are mapped, including possibly the largest known up to date paleo‐...

We use optical satellite data to map the co-seismic displacements for the Mw=7.5 strike-slip earthquake of 28 September 2018 in Palu, Sulawesi, Indonesia. This was a strike-slip faulting event at shallow depth that occurred within the interior of the Molucca Sea microplate, which is part of the Sunda tectonic plate. Using optical image correlation...

A strong, shallow earthquake occurred near Heraklion (Crete, Greece) on 27 September 2021. The earthquake produced significant ground deformation in the vicinity of Arkalochori village but without any evidence for surface ruptures of primary origin. We used geodetic (InSAR and GNSS) data to map motions of the Earth’s surface that occurred during an...

Two strong earthquakes hit Thessaly region on March 3rd, 2021 (M w = 6.3) and on March 4th, 2021 (M w = 6.1). The epicentres of the earthquakes were located at approximately 23 and 29 km respectively NW of Larissa, one of the most populous cities in Greece. Several aftershocks followed thereafter. Although no injuries were recorded, several structu...

Timely and rational prediction of coseismic landslides is crucial for the design and development of key infrastructure capable to protect human lives in seismically active regions. This research introduces the novel Hybrid Coseismic Landslide Forecasting model (COLAFOS) that takes into consideration three parameters namely: The Average Slope of the...

On 29 December 2020, a shallow earthquake of magnitude Mw 6.4 struck northern Croatia, near the town of Petrinja, more than 24 hours after a strong foreshock (Ml 5). We formed a reconnaissance team of European geologists and engineers, from Croatia, Slovenia, France, Italy and Greece, rapidly deployed in the field to map the evidence of coseismic e...

The March 2021 Thessaly, Central Greece, seismic sequence characterized by an Mw = 6.3 mainshock and five Mw > 5.0 aftershocks triggered extensive liquefaction in the floodplain of the Piniada Valley and localized phenomena along the riverbanks of the Titarissios River. In order to document these secondary effects, we carried out immediate post eve...

Coseismic Landslides (COLA) are one of the most widespread and destructive hazards to result from earthquakes in mountainous environments. They are always associated with almost instantaneous slope collapse and spreading, posing significant hazards to human lives and lifeline facilities worldwide. Current methods to identify COLA immediately after...

Here we present a joint analysis of the geodetic, seismological and geological data of the March 2021 Northern Thessaly seismic sequence, that were gathered and processed as of April 30, 2021. First, we relocated seismicity data from regional and local networks and inferred the dip-direction (NE) and dip-angle (38°) of the March 3, 2021 rupture pla...

The island of Lefkada, Greece periodically suffered environmental and structural damages induced by earthquakes. During the twenty-first century, two moderate events of magnitude M > 6 occurred in 2003 and 2015 (M6.2 and M6.5, respectively). The dominant type of the earthquake-induced environmental failures was rock falls and slides that were wides...

This paper presents a joint analysis of instrumental and macroseismic data regarding the 19 July 2019, Greece Mw5.1 earthquake occurred west of Athens. This earthquake ruptured a blind, south-dipping normal fault, 23 km WNW of the center of Athens, while its relocated epicentre lies in close vicinity to the one of the 1999 Mw6.0 earthquake. The max...

On 30 October 2020, a large Mw = 7.0 earthquake occurred north of the island of Samos, Greece. Here we present the characteristics of the seismic fault (location, geometry, geodetic moment) as inferred from the processing of geodetic data (InSAR and GNSS). We use the InSAR displacement data from Sentinel-1 interferograms (ascending orbit 29 and des...

The 29 December 2020, Mw 6.4 Petrinja earthquake nucleated at a depth of~10 km in the Sisak-Moslavina County in northern Croatia,~6 km WSW of the Petrinja town. Focal mechanisms, aftershocks distribution, and preliminary Sentinel-1 InSAR interferogram suggest that the NW-SE right-lateral strike-slip Pokupsko-Petrinja fault was the source of this ev...

On March 3, 2021 a Mw=6.3 shallow earthquake occurred in the mountainous region of Damasi, about 20 km to the northwest of Larisa, Thessaly, central Greece, in a region of active crustal extension but of low strain. This event was followed by a Mw=6.0 shallow earthquake on March 4, 2021 about 12 km to the northwest, inside the sedimentary basin of...

On the 3rd and 4th of March 2021, two strong earthquakes of M6.3 and M6.0, respectively occurred at Thessaly, Central Greece. During extensive field survey and mapping, accompanied by UAV aerial surveys, following the strong earthquakes, numerous (more than 400 cases) liquefaction-related features were identified, including sand blows and craters,...

The correlation of coseismic landslides with the seismic and morphological parameters has been investigated in detail by many researchers, mainly after the devastating 2008 M8.0 Wenchuan, China earthquake. One of the goals of such studies is to examine the spatial distribution of the earthquake-induced landslides in order to establish a pattern dep...

A Correction to this paper has been published: https://doi.org/10.1038/s43247-021-00109-7

The present-day hydrographic network of the Pinios River, Greece, clearly shows some major morphological and hydrographic anomalies documenting its complex evolution. A critical analysis and re-interpretation of geological and historical/modern topographic data clearly indicate an original subdivision of Thessaly into two separate endorheic hydrogr...

Here, we present the source mechanism and rupture process for the destructive 24 January 2020 Mw 6.7 Doğanyol–Sivrice earthquake at the East Anatolian Fault Zone (EAFZ, Turkey), obtained from seismological waveform analysis and space geodetic observations. Multi-data analyses and modelling in the present study provide fundamental data and strong co...

The 2020 Mw 5.8 Lone Pine earthquake, the largest earthquake on the Owens Valley fault zone, eastern California, since the nineteenth century, ruptured an extensional stepover in that fault. Owens Valley separates two normal‐faulting regimes, the western margin of the Great basin and the eastern margin of the Sierra Nevada, forming a complex seismo...

On September 17-20 2020 Medicane Ianos impacted Greece. The Medicane was associated with significant wind speeds, and precipitation. The amount of precipitation during a duration of about ~48 hrs was among the highest recorded in certain areas and exceeded in certain areas the mean annual precipitation. The extent of the affected area was very larg...

Soil liquefaction in the free field usually results in the generation of sand craters and volcanoes, as well as in surface ground cracks due to subsidence and lateral displacements. Technical constructions built on or within liquefiable soils may exhibit liquefaction-induced structural damages due to differential settlements, displacements and/or t...

Integration and harmonization of the most recent seismological, geological, tectonic, geophysical and geodetic datasets, with the aim of capturing the potential of ground deformation towards a more reliable evaluation of seismic risk at a national level.

This paper presents a joint analysis of relocation of earthquake epicenter and aftershock sequence, macroseismic intensity assignment and distribution, strong motion data analysis and a fault model regarding the 19 July 2019 Athens, Greece M w 5.1 earthquake. This earthquake ruptured a blind, south-dipping normal fault at the northwestern edge of T...

We identify the source of the Mw = 5.6 earthquake that hit west-central Epirus on 21 March 2020 00:49:52 UTC. We use Sentinel-1 synthetic aperture radar interferograms tied to one permanent Global Navigation Satellite System (GNSS) station (GARD). We model the source by inverting the INSAR displacement data. The inversion model suggests a shallow s...

Knowledge and visualization of the present-day relationship between earthquakes, active tectonics and crustal deformation is a key to understanding geodynamic processes, and is also essential for risk mitigation and the management of geo-reservoirs for energy and waste. The study of the complexity of the Greek tectonics has been the subject of inte...

Plain Language Summary The 2018 Kaktovik event is the largest earthquake ever to be reported and recorded within the eastern Brooks Range and presents an unprecedented opportunity to study the regional tectonic structure and crustal deformation. Here, we present a detailed investigation into the seismogenic structure of this earthquake sequence, wh...

Earthquake occurrence is ultimately controlled by tectonic stress load. Nevertheless, the 2019, Mw = 4.9, Le Teil earthquake in southern France occurred in an area where strain rates are relatively low. Human operations can produce increases in stress load and degradation of strength on nearby active faults, which raises the potential for failure....

We identify the source of the Mw = 5.6 earthquake that hit west-central Epirus on March 21, 2020 00:49:52 UTC. We use synthetic aperture radar interferograms tied to one permanent Global Navigation Satellite System (GNSS) station (GARD). We model the source by inverting the INSAR displacement data. The inversion model suggests a shallow source on a...

Here, we present the results of a kinematic slip model of the 2020 Mw 6.7 Doğanyol-Sivrice, Turkey Earthquake, the most important event in the last 50 yr on the East Anatolian Fault Zone. Our slip model is constrained by two Sentinel-1 interferograms and by 5 three-component high-rate GNSS (Global Navigation Satellite System) recordings close to th...

In the last decades, the triggered seismicity has represented one of the most debated issue. Fluid pressure changes with/without fluid flow in rock fractures/pores, thermal stress changes due to temperature gradients, and the volumetric changes or mass removal/accumulation can be included in the geoengineering processes that can induce or trigger s...

We identify the source of the Mw = 6.4 earthquake that rocked north-central Albania on November 26, 2019 02:54 UTC. We use synthetic aperture radar interferograms tied to the time series of coordinates of two permanent Global Navigation Satellite System (GNSS) stations (DUR2 and TIR2). We model the source by inverting the displacement data. Assumin...

Twitter is an established social media platform valued by scholars as an open way to disseminate scientific information and to publicly discuss research results. Scientific discussions on Twitter are viewed by the media, who can then pass on information to the wider public. Social media is used widely by geoscientists, but there is little documenta...

Knowledge of the present-day relationships between earthquakes, active tectonics, and crustal deformation is a key for understanding the geodynamics, ongoing surface processes (i.e. erosion, sedimentation, etc.) and is also essential for the risk assessment and management of geo-reservoirs for energy and waste. Greece is characterized by the most t...

We combine almost 10 years of continuous GNSS observations at four permanent stations with groundwater and rainfall data to investigate subsidence patterns in the region of Thessaly, central Greece. Thessaly is a key area for studying anthropogenic versus tectonic subsidence in Greece because it is (a) characterized by overexploitation of groundwat...

Seismically generated landslides represent one of the most damaging hazards associated with earthquakes in countries with high seismicity. The delineation of prone to coseismic landsliding areas is crucial in order to predict the occurrence of earthquake-induced landslides and consequently reduce the relevant risk. The goal of this study is to inve...

Terrestrial LiDAR (TLS), photogrammetric and field data were collected during the years 2014, 2015 and 2017, at a 20-m long limestone scarp locality along the N–S striking, 70° west-dipping, active Pidima fault (Messinia, SW Peloponnese, Greece). This locality presents an artificially exhumed portion of an active fault plane, thus providing a uniqu...

Here we present the results of a kinematic slip model of the 2020 Mw 6.7 Doğanyol-Sivrice, Turkey Earthquake, the most important event in the last 50 years on the East Anatolian Fault zone. Our slip model is constrained by two Sentinel-1 interferograms and by 5 three-component high-rate GNSS recordings close to the earthquake source. We find that m...

Point cloud extracted from stereo aerial imagery (IGN)covers the area of La Rouviere fault, near Montelimar, SE France. La Rouvierefault, an old tectonic featurewith an approximate strike of NE-SW, was re-activated and ruptured during the November 11 2019 Mw 4.9 shallow earthquake. First results from SAR Interferometry and fieldsurveys confirm surf...

Abstract. Twitter is an established social media platform valued by scholars as an open way to disseminate scientific information and to publicly discuss research results. Scientific discussions are widely viewed by the media who can then pass on information to the wider public. Here, we take the example of two 2018 earthquake-related events which...

On July 20, 2017 22:31 UTC, a strong M w = 6.6 earthquake occurred at shallow depth between Kos Island (Greece) and Bodrum (Turkey). We derive a co-seismic fault model from joint inversion of geodetic data (GNSS and InSAR) assuming that the earthquake can be modelled by the slip of a rectangular fault buried in an elastic and homogeneous half-space...

The 1987 to 2019 Tennant Creek earthquake sequence comprises three 1988 surface-rupturing mainshocks (moment magnitude (Mw 6.2, 6.3, and 6.5) that occurred within a 12-hour period, a preceding foreshock sequence commencing in 1987, and a prolonged aftershock sequence including a Mw 5.0 earthquake on the 1st August 2019. Each surface rupturing event...

On 19 July 2019, 11:13 GMT (14:13 local time), a strong, damaging earthquake with magnitude Mw5.1 (Figure 1) and 16 km depth (NKUA solution) struck Athens, causing damage to its western suburbs. The epicentre is located a few km north of Magoula (west Attica) and it is associated with a normal fault probably comprising the western segment of Parnit...

Preliminary macroseismic report of the 19 July 2019 Athens earthquake of Magnitude Mw5.1. Published in EMSC-CSEM: https://www.emsc-csem.org/Files/news/EMSC/Kouskouna_etal_Athens_2019_eq_report_final_lowres_v2.pdf

The Athens 19/07/2019 Mw5.1 earthquake – Preliminary macroseismic report

On 2017 and 2018 four strong/moderate earthquakes occurred at shallow focal depths in the East Mediterranean. They share a common characteristic, which is that a large part of the induced ground deformation is offshore, thus a part of the deformation footprint is missing. Assuming that the deformation source of an earthquake can be modelled by the...

The Horizontal to Vertical Spectral Ratio, or "HVSR", has become popular in the last decades, especially because it leverages on inexpensive equipment and minimal workforce. One of the most attractive aspect is that elastic shear wave resonance frequency of a sedimentary basin can be retrieved and readily used to obtain an estimate of the depth of...

The earthquake Mw6.6 (macroseismic intensity VIII, ESI-07 scale) that occurred on July 20, 2017 at 22:31 UTC (01:31 local time) in Gökova Bay, SE Aegean Sea, induced minor damages to contemporary structures at the island of Kos, Greece, while severe damages were reported on Venetian and Ottoman-era constructions, causing two deaths. Focusing on the...