Tsunamigenic potential of a Holocene submarine landslide along the North Anatolian Fault (northern Aegean Sea, off Thasos island): insights from numerical modelling

The North Anatolian Fault in the northern Aegean Sea triggers frequent earthquakes of magnitudes up to Mw∼7. This seismicity can be a source of modest tsunamis for the surrounding coastlines with less than 50&thinsp;cm height according to numerical modelling and analysis of tsunami deposits. However, other tsunami sources may be involved, like submarine landslides. We assess the severity of this potential hazard by performing numerical simulations of tsunami generation and propagation from a Holocene landslide (1.85&thinsp;km3 in volume) identified off Thasos. We use a model coupling the simulation of the submarine landslide, assimilated to a granular flow, to the propagation of the tsunami wave. The results of these simulations show that a tsunami wave of water height between 1.10 and 1.65&thinsp;m reaches the coastline at Alexandroupoli (58&thinsp;000 inhabitants) 1&thinsp;h after the triggering of the landslide. In the same way, tsunami waves of water height between 0.80 and 2.00&thinsp;m reach the coastline of the Athos peninsula 9&thinsp;min after the triggering of the landslide. Despite numerous earthquakes of Mw&gt;7 and strong detrital input (on the order of 30&thinsp;cm ka−1), only a few Holocene landslides have been recognized so far, asking for tsunami recurrence in this area.</p

European Multidisciplinary and Water-Column Observatory - European Research Infrastructure Consortium (EMSO ERIC): challenges and opportunities for strategic European marine sciences

EMSO (European Multidisciplinary Seafloor and water-column Observatory, www.emso-eu.org) is a large‐scale European Research Infrastructure I. It is a distributed infrastructure of strategically placed, deep‐sea seafloor and water column observatory nodes with the essential scientific objective of real‐time, longterm observation of environmental processes related to the interaction between the geosphere, biosphere, and hydrosphere. The geographic locations of the EMSO observatory nodes represent key sites in European waters, from the Arctic, through the Atlantic and Mediterranean, to the Black Sea (Figure 1), as defined through previous studies performed in FP6 and FP7 EC projects such as ESONET‐CA, ESONET‐NoE, EMSO-PP (Person et al., 2015)Peer Reviewe

Preliminary results of high resolution paleoceanography and paleoclimatology during sapropel S1 deposition (South Limnos Basin, North Aegean Sea).

Οι παλαιοπεριβαλλοντικές συνθήκες κατά τη διάρκεια απόθεσης του σαπροπηλού S1 στο Βόρειο Αιγαίο (πυρήνας βαρύτητας Μ-4, μήκους 2,53 m, λεκάνης νότιας Λήμνου) προσδιορίζονται με βάση την ποσοτική ανάλυση μικροπαλαιοντολογικών (βενθονικά και πλαγκτονικά τρηματοφόρα) και γεωχημικών (OC, δ13Corg) δεικτών. Χαρακτηριστικό του πυρήνα Μ-4 είναι η μεγάλη εμφάνιση του S1 που φτάνει το πάχος των 96 cm. Η μελέτη κατέδειξε ότι, το κατώτερο σαπροπηλικό στρώμα S1a αποτέθηκε σε θερμότερες συνθήκες, εντονότερης δυσοξίας, σε σχέση με το ανώτερο σαπροπηλικό στρώμα S1b.. Αύξηση της παραγωγικότητας και καλύτερη διατήρηση του οργανικού υλικού πιστοποιήθηκαν στο κατώτερο τμήμα του S1. Η διακοπή των σαπροπηλικών συνθηκών στα 8,0 Ka BP που χαρακτηρίζεται κυρίως από την αύξηση της σχετικής συχνότητας των συμφυρματοπαγών μορφών των βενθονικών τρηματοφόρων υποστηρίζει συνθήκες υψηλής οξυγόνωσης του πυθμένα και εισροή γλυκών υδάτων.The paleoenviromental conditions during the depositional interval of sapropel S1 in the northeastern Aegean (gravity core M-4, length 2.53 m; south Limnos basin) are studied based on quantitative micropaleontological (benthic and planktonic foraminifera) and geochemical (OC, δ13Corg) analyses. Special feature of core M-4 is the thickness of S1 layer (96 cm). Our study points that sapropelic layer S1a has been deposited in more dysoxic and warmer conditions in respect to S1b. Both primary productivity and preservation of organic material are more intense during the lower part of S1. An interruption of the sapropelic conditions at 8.0 Ka BP which is mainly characterized by the increase of agglutinated foraminiferal forms confirms both higher oxygen bottom conditions and freshwater input

Phylogeography of Aegean green toads (Bufo viridis subgroup): continental hybrid swarm vs. insular diversification with discovery of a new island endemic

BACKGROUND: Debated aspects in speciation research concern the amount of gene flow between incipient species under secondary contact and the modes by which post-zygotic isolation accumulates. Secondary contact zones of allopatric lineages, involving varying levels of divergence, provide natural settings for comparative studies, for which the Aegean (Eastern Mediterranean) geography offers unique scenarios. In Palearctic green toads (Bufo viridis subgroup or Bufotes), Plio-Pleistocene (~ 2.6 Mya) diverged species show a sharp transition without contemporary gene flow, while younger lineages, diverged in the Lower-Pleistocene (~ 1.9 Mya), admix over tens of kilometers. Here, we conducted a fine-scale multilocus phylogeographic analysis of continental and insular green toads from the Aegean, where a third pair of taxa, involving Mid-Pleistocene diverged (~ 1.5 Mya) mitochondrial lineages, earlier tentatively named viridis and variabilis, (co-)occurs. RESULTS: We discovered a new lineage, endemic to Naxos (Central Cyclades), while coastal islands and Crete feature weak genetic differentiation from the continent. In continental Greece, both lineages, viridis and variabilis, form a hybrid swarm, involving massive mitochondrial and nuclear admixture over hundreds of kilometers, without obvious selection against hybrids. CONCLUSIONS: The genetic signatures of insular Aegean toads appear governed by bathymetry and Quaternary sea level changes, resulting in long-term isolation (Central Cyclades: Naxos) and recent land-bridges (coastal islands). Conversely, Crete has been isolated since the end of the Messinian salinity crisis (5.3 My) and Cretan populations thus likely result from human-mediated colonization, at least since Antiquity, from Peloponnese and Anatolia. Comparisons of green toad hybrid zones support the idea that post-zygotic hybrid incompatibilities accumulate gradually over the genome. In this radiation, only one million years of divergence separate a scenario of complete reproductive isolation, from a secondary contact resulting in near panmixia

Detection potential of the KM3NeT detector for high-energy neutrinos from the Fermi bubbles

A recent analysis of the Fermi Large Area Telescope data provided evidence for a high-intensity emission of high-energy gamma rays with a E 2 spectrum from two large areas, spanning 50 above and below the Galactic centre (the ‘‘Fermi bubbles’’). A hadronic mechanism was proposed for this gamma-ray emission making the Fermi bubbles promising source candidates of high-energy neutrino emission. In this work Monte Carlo simulations regarding the detectability of high-energy neutrinos from the Fermi bubbles with the future multi-km3 neutrino telescope KM3NeT in the Mediterranean Sea are presented. Under the hypothesis that the gamma-ray emission is completely due to hadronic processes, the results indicate that neutrinos from the bubbles could be discovered in about one year of operation, for a neutrino spectrum with a cutoff at 100 TeV and a detector with about 6 km3 of instrumented volume. The effect of a possible lower cutoff is also considered.Published7–141.8. Osservazioni di geofisica ambientaleJCR Journalrestricte

Expansion cone for the 3-inch PMTs of the KM3NeT optical modules

[EN] Detection of high-energy neutrinos from distant astrophysical sources will open a new window on the Universe. The detection principle exploits the measurement of Cherenkov light emitted by charged particles resulting from neutrino interactions in the matter containing the telescope. A novel multi-PMT digital optical module (DOM) was developed to contain 31 3-inch photomultiplier tubes (PMTs). In order to maximize the detector sensitivity, each PMT will be surrounded by an expansion cone which collects photons that would otherwise miss the photocathode. Results for various angles of incidence with respect to the PMT surface indicate an increase in collection efficiency by 30% on average for angles up to 45 degrees with respect to the perpendicular. Ray-tracing calculations could reproduce the measurements, allowing to estimate an increase in the overall photocathode sensitivity, integrated over all angles of incidence, by 27% (for a single PMT). Prototype DOMs, being built by the KM3NeT consortium, will be equipped with these expansion cones.This work is supported through the EU, FP6 Contract no. 011937, FP7 grant agreement no. 212252, and the Dutch Ministry of Education, Culture and Science.Adrián Martínez, S.; Ageron, M.; Aguilar, JA.; Aharonian, F.; Aiello, S.; Albert, A.; Alexandri, M.... (2013). Expansion cone for the 3-inch PMTs of the KM3NeT optical modules. Journal of Instrumentation. 8(3):1-19. https://doi.org/10.1088/1748-0221/8/03/T03006S1198