Modelling of combined Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) data was performed to characterize the source of the Mw6.9 earthquake that ...occurred to the north of Samos Island (Aegean Sea) on 30 October 2020. Pre-seismic analysis revealed an NNE–SSW extensional regime with normal faults along an E–W direction. Co-seismic analysis showed opening of the epicentral region with horizontal and vertical displacements of ~350 mm and ~90 mm, respectively. Line-of-sight (LOS) interferometric vectors were geodetically corrected using the GNSS data and decomposed into E–W and vertical displacement components. Compiled interferometric maps reveal that relatively large ground displacements had occurred in the western part of Samos but had attenuated towards the eastern and southern parts. Alternating motions occurred along and across the main geotectonic units of the island. The best-fit fault model has a two-segment listric fault plane (average slip 1.76 m) of normal type that lies adjacent to the northern coastline of Samos. This fault plane is 35 km long, extends to 15 km depth, and dips to the north at 60° and 40° angles for the upper and lower parts, respectively. A predominant dip-slip component and a substantial lateral one were modelled.
Eastern Mediterranean Sea has experienced four tsunamigenic earthquakes since 2017, which delivered moderate damage to coastal communities in Turkey and Greece. The most recent of these tsunamis ...occurred on 30 October 2020 in the Aegean Sea, which was generated by an M
w
7.0 normal-faulting earthquake, offshore Izmir province (Turkey) and Samos Island (Greece). The earthquake was destructive and caused death tolls of 117 and 2 in Turkey and Greece, respectively. The tsunami produced moderate damage and killed one person in Turkey. Due to the semi-enclosed nature of the Aegean Sea basin, any tsunami perturbation in this sea is expected to trigger several basin oscillations. Here, we study the 2020 tsunami through sea level data analysis and numerical simulations with the aim of further understanding tsunami behavior in the Aegean Sea. Analysis of data from available tide gauges showed that the maximum zero-to-crest tsunami amplitude was 5.1–11.9 cm. The arrival times of the maximum tsunami wave were up to 14.9 h after the first tsunami arrivals at each station. The duration of tsunami oscillation was from 19.6 h to > 90 h at various tide gauges. Spectral analysis revealed several peak periods for the tsunami; we identified the tsunami source periods as 14.2–23.3 min. We attributed other peak periods (4.5 min, 5.7 min, 6.9 min, 7.8 min, 9.9 min, 10.2 min and 32.0 min) to non-source phenomena such as basin and sub-basin oscillations. By comparing surveyed run-up and coastal heights with simulated ones, we noticed the north-dipping fault model better reproduces the tsunami observations as compared to the south-dipping fault model. However, we are unable to choose a fault model because the surveyed run-up data are very limited and are sparsely distributed. Additional researches on this event using other types of geophysical data are required to determine the actual fault plane of the earthquake.
La densidad y las particularidades que los poblados de la Edad del Hierro tienen en Galicia los han convertido en elementos estructuradores del territorio y portadores de una fortísima carga ...simbólica a lo largo de los siglos, hasta hoy. El duradero e irregular proceso de desaparición del modelo castral hacia una red campesina de asentamientos abiertos en los valles y llanuras parece haberse culminado en la Alta Edad Media, cuando las villae, predecesoras de las aldeas y parroquias de época feudal, son ya la célula de población hegemónica. En el presente trabajo analizaremos el papel social que tenían los castros en el valle del Sarria en esa altura basándonos en el análisis de los documentos del tumbo de Samos y en el estudio histórico del paisaje. gl A densidade e as particularidades que os poboados da Idade do Ferro teñen en Galiza convertéronos en elementos estruturadores do territorio e portadores dunha fortísima carga simbólica ao longo dos séculos, até hoxe. O duradeiro e irregular proceso de desaparición do modelo castral cara a unha rede campesiña de asentamentos abertos nos vales e chairas parece terse culminado na Alta Idade Media, cando as villae, predecesoras das aldeas e parroquias de época feudal, son xa a célula de poboación hexemónica. No presente traballo analizaremos o papel social que tiñan os castros no val do Sarria nesa altura baseándonos na análise dos documentos do tombo de Samos e no estudo histórico da paisaxe.
The eastern parts of the Aegean Sea were struck by a destructive M
W
6.9 earthquake on 30 October 2020 at 11:51:27 UTC. The earthquake ruptured an East-West trending normal fault in the Aegean Sea ...between the northern coast of Samos Island and the southern coast of İzmir and also triggered a medium level tsunami and thousands of aftershocks across the region. 119 fatalities, 1,051 injuries, and many collapsed buildings were reported due to the earthquake in the affected region. The most catastrophic consequences of the earthquake were registered in the Bayraklı and Bornova districts, which are built on a deep alluvial Basin approximately 60–70 km away from the epicentre of the mainshock. This paper explains the damage with an extensive dataset of ground motion records of the mainshock and aftershocks, which are provided by both Greek and Turkish networks. A set of ground motion parameters such as peak ordinates, spectral quantities, intensity measures and duration parameters are calculated and analysed. The closest softer soil station in Samos Island produces the highest peak ground acceleration and velocity. The ground motion models employed commonly for the region overestimate the observed data beyond 60–70 km of Joyner-Boore distance except for the recently published local ground motion model, which utilises local earthquakes in the derivation of the model. Contrary to expectations, stiff soil recordings exhibit considerable spectral accelerations in the long period region, similar to those in soft soils. The calculated ground motion parameters are correlated with the results of the hybrid reconnaissance mission, organized by the Earthquake Engineering Field Investigation Team (EEFIT). Although the peak values and regarded intensity measures clearly highlight the variability in soil conditions in the most damaged area (Bayraklı and Bornova), velocity-based ground motion parameters seem to be the more responsive damage indicators. The spectral shapes of the normalised response spectra in the İzmir Basin are not compatible with the 2018 Turkish seismic code spectrum whereas their response spectra are below the 475-years return period design spectra provided in outdated and current Turkish seismic codes.
The tsunami generated by the offshore Samos Island earthquake (Mw = 7.0, 30 October 2020) is the largest in the Aegean Sea since 1956 CE. Our study was based on field surveys, video records, ...eyewitness accounts and far-field mareograms. Sea recession was the leading motion in most sites implying wave generation from seismic dislocation. At an epicentral distance of ~12 km (site K4, north Samos), sea recession, followed by extreme wave height (h~3.35 m), occurred 2′ and 4′ after the earthquake, respectively. In K4, the main wave moved obliquely to the coast. These features may reflect coupling of the broadside tsunami with landslide generated tsunami at offshore K4. The generation of an on-shelf edge-wave might be an alternative. A few kilometers from K4, a wave height of ~1 m was measured in several sites, except Vathy bay (east, h = 2 m) and Karlovasi port (west, h = 1.80 m) where the wave amplified. In Vathy bay, two inundations arrived with a time difference of ~19′, the second being the strongest. In Karlovasi, one inundation occurred. In both towns and in western Turkey, material damage was caused in sites with h > 1 m. In other islands, h ≤ 1 m was reported. The h > 0.5 m values follow power-law decay away from the source. We calculated a tsunami magnitude of Mt~7.0, a tsunami source area of 1960 km2 and a displacement amplitude of ~1 m in the tsunami source. A co-seismic 15–25 cm coastal uplift of Samos decreased the tsunami run-up. The early warning message perhaps contributed to decrease the tsunami impact.
An almost complete skull and a second partial skull of Bohliniaattica (Artiodactyla: Giraffidae) from the late Miocene of Maragheh in northwestern Iran is described along with a complete upper ...dentition from Samos in Greece. These specimens enrich what is known of this species. The skull has massive bent ossicones. The braincase is horizontal to the face in lateral view. The upper premolars have strongly curved styles. The metapodials of this species are elongate with a deep plantar trough. The braincase is short and the occipital does not extend caudally. The type material of Bohlinia is from Pikermi but this taxon is also known from localities in F.Y.R.O. Macedonia, Greece, Turkey, Bulgaria, Iraq, and Iran. The new specimens are similar to others except that the ossicone terminates in a knob and the palatine choanae are positioned caudally. This taxon along with Honanotherium, which is most similar but with shorter metapodials and simpler premolars, can be placed in the subfamily Bohlininae.
Slab tearing below western Turkey had first-order tectonic and magmatic consequences by inducing a lateral gradient of extension in the upper plate and toroidal flow of asthenosphere that affected ...the typology and distribution of melts at the surface. But the coupling mechanisms between the 3D mantle flow at depth and deformation in the upper plate above a slab tear have received little attention so far. This paper is focused on the description of the distribution and kinematics of deformation in the eastern part of the Aegean Sea, within the transition zone between the Cyclades and the Menderes Massif, which have been little studied. By investigating the Dodecanese and Eastern Aegean islands, we thus complete the description of the extensional strain field in the overriding plate around the slab tear. There, extension related to slab retreat and tearing keeps a constant NNE-SSW direction accommodating the difference in finite rates of extension, without localized crustal-scale strike-slip faults and block rotations above the tear. In addition, despite the complexity involved in the Aegean-Anatolian orogenic wedge, a similar structural position is recognized through the entire region. From top to bottom, we found that (i) the Lycian units which were exhumed earlier, in the Late Cretaceous, (ii) the higher-pressure and higher-temperature units (i.e. the Upper Cycladic Blueschist Nappe), with exception of the Vourliotes nappe in Samos, and finally (iii) the colder units such as Amorgos unit, the Menderes and its cover before the Main Menderes Metamorphism overprint and the Lower Cycladic Blueschist Nappe (e.g. Milos, Folegandros, a part of the Dodecanese and Fourni islands).
•Extension in Dodecanese and Fourni islands is accommodated by low-angle detachments.•Consistent NNE-SSW-directed flow in lower crust above slab tear in Aegean/Anatolian transition zone•No localized strike-slip deformation in the lower crust above slab tearing•Three “nappes” are distinguished in the orogenic wedge with different P-T conditions.
An earthquake of magnitude 6.9 hit the city of Izmir (Turkey) on 30 October 2020, resulting in 117 deaths (in Turkey) and considerable economic losses. The earthquake also triggered a tsunami. ...Following the earthquake, field surveys are being conducted in a
Covid-secure
way to study and document the damages caused. The earthquake caused significant damages to residential buildings mainly located in the district of Bayrakli and Bornova. However, no damages were observed in railway and roadway bridges or tunnels and that helped the rescue operations. The damages were mainly structural which included the so-called pancake collapse (where the entire building collapsed) and soft storey type collapse (weak storey characterised with weak columns collapsed), and in some cases, only the ground floor completely collapsed. Due to the proximity of the epicentre and the geology of the area, it seemed that the ground motions were amplified. This technical note provides a summary of the seismological and recorded ground characteristics of the earthquake together with the lessons learnt.
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