14 research outputs found

    Gas and seismicity within the Istanbul seismic gap

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    Understanding micro-seismicity is a critical question for earthquake hazard assessment. Since the devastating earthquakes of Izmit and Duzce in 1999, the seismicity along the submerged section of North Anatolian Fault within the Sea of Marmara (comprising the “Istanbul seismic gap”) has been extensively studied in order to infer its mechanical behaviour (creeping vs locked). So far, the seismicity has been interpreted only in terms of being tectonic- driven, although the Main Marmara Fault (MMF) is known to strike across multiple hydrocarbon gas sources. Here, we show that a large number of the aftershocks that followed the M 5.1 earthquake of July, 25th 2011 in the western Sea of Marmara, occurred within a zone of gas overpressuring in the 1.5–5 km depth range, from where pressurized gas is expected to migrate along the MMF, up to the surface sediment layers. Hence, gas-related processes should also be considered for a complete interpretation of the micro- seismicity (~M < 3) within the Istanbul offshore domain

    Gas and seismicity within the Istanbul seismic gap

    Get PDF
    Understanding micro-seismicity is a critical question for earthquake hazard assessment. Since the devastating earthquakes of Izmit and Duzce in 1999, the seismicity along the submerged section of North Anatolian Fault within the Sea of Marmara (comprising the “Istanbul seismic gap”) has been extensively studied in order to infer its mechanical behaviour (creeping vs locked). So far, the seismicity has been interpreted only in terms of being tectonic-driven, although the Main Marmara Fault (MMF) is known to strike across multiple hydrocarbon gas sources. Here, we show that a large number of the aftershocks that followed the M 5.1 earthquake of July, 25th 2011 in the western Sea of Marmara, occurred within a zone of gas overpressuring in the 1.5–5 km depth range, from where pressurized gas is expected to migrate along the MMF, up to the surface sediment layers. Hence, gas-related processes should also be considered for a complete interpretation of the micro-seismicity (~M < 3) within the Istanbul offshore domain

    Vrancea slab earthquakes triggered by static stress transfer

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    The purpose of this paper is to study the interaction of the Vrancea seismic activity (Romania) in space as result of Coulomb, static stress transfer during &lt;i&gt;M&lt;/i&gt;=7+ events. In this area, three large events occurred in 1977, 1986 and 1990 at mid-lower, lithospheric depths and with similar focal mechanisms. Assuming elastic rheology for the deforming rocks it is suggested that frictional sliding on pre-existing fault produced the 1986 &lt;i&gt;M&lt;/i&gt;=7.1 event (depth 131 km), that was possibly triggered by the 1977 &lt;i&gt;M&lt;/i&gt;=7.4 event (depth 94 km). We calculated a static stress transfer of 0.52–0.78 bar to the hypocentre of the 1986 event. On the contrary, the occurrence of the 1990 event is uncertain: it is located inside the relaxed (shadow) zone of the combined 1977 and 1986 static stress field considering an azimuth for maximum compression of N307° E. It follows that, the 1990 earthquake most likely represents an unbroken patch (asperity) of the 1977 rupture plane that failed due to loading. However, if a different compression azimuth is assumed (N323° E) then the 1990 event was also possibly triggered by static stress transfer of the 1977 and 1986 events (combined). Our modeling is a first-order approximation of the kind of earthquake interaction we might expect at intermediate lithospheric depths (80–90 to 130–140 km). It is also suggested that static stress transfer may explain the clustering of Vrancea earthquakes in space by the rupturing of two (possibly three) NW-dipping major zones of weakness (faults) which accommodate the extension (vertical elongation) of the slab

    On the Mw 6.4 SW-Achaia (western Greece) earthquake sequence of 8 June 2008: Seismological, field, GPS observations and stress modeling

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    On 8 June 2008 an Mw(NOA)=6.4 earthquake occurred in NW Peloponnesus, western Greece. This event is the largest strike-slip earthquake to occur in western Greece during the past 25 years. The hypocentre was determined at 18 km depth beneath village Mihoi in SW Achaia. No surface rupture was observed. Many rock falls, slides and liquefaction features have been found as is typical for an earthquake of this size. Double-difference relocations of 370 aftershocks show a linear pattern of events and define a clear NE-SW striking mainshock fault plane. The aftershock region extends approximately 30 km in length, and the width of the surface projection of the aftershocks is as large as 10 km. The depth of the aftershocks rarely exceeds 22 km. Analysis of high-rate GPS data showed that station RLS (Riolos) which is located 12.8 km N5°W of the epicentre was displaced co-seismically 7 mm to the North in agreement with right-lateral kinematics of the rupture. Static (Coulomb) stress transfer analysis indicates loading of faults near the towns of Patras (north) and Amaliada (south), respectively. The earthquake put more emphasis on the role of strike-slip fault in the deformation of western Greece also indicating that seismic strain is partitioned between strike-slip and normal-slip events due to obliquity of the Nubia (Africa) subduction and the N-S extension of the overriding Aegean upper plateSubmitted1.9. TTC - Rete GPS nazionaleJCR Journalreserve

    On the Mw 6.4 SW-Achaia (western Greece) earthquake sequence of 8 June 2008: Seismological, field, GPS observations and stress modeling

    No full text
    On 8 June 2008 an Mw(NOA)=6.4 earthquake occurred in NW Peloponnesus, western Greece. This event is the largest strike-slip earthquake to occur in western Greece during the past 25 years. The hypocentre was determined at 18 km depth beneath village Mihoi in SW Achaia. No surface rupture was observed. Many rock falls, slides and liquefaction features have been found as is typical for an earthquake of this size. Double-difference relocations of 370 aftershocks show a linear pattern of events and define a clear NE-SW striking mainshock fault plane. The aftershock region extends approximately 30 km in length, and the width of the surface projection of the aftershocks is as large as 10 km. The depth of the aftershocks rarely exceeds 22 km. Analysis of high-rate GPS data showed that station RLS (Riolos) which is located 12.8 km N5°W of the epicentre was displaced co-seismically 7 mm to the North in agreement with right-lateral kinematics of the rupture. Static (Coulomb) stress transfer analysis indicates loading of faults near the towns of Patras (north) and Amaliada (south), respectively. The earthquake put more emphasis on the role of strike-slip fault in the deformation of western Greece also indicating that seismic strain is partitioned between strike-slip and normal-slip events due to obliquity of the Nubia (Africa) subduction and the N-S extension of the overriding Aegean upper plat

    Vanadium-induced apoptosis of HaCaT cells is mediated by c-fos and involves nuclear accumulation of clusterin

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    Vanadium exerts a variety of biological effects, including antiproliferative responses through activation of the respective signaling pathways and the generation of reactive oxygen species. As epidermal cells are exposed to environmental insults, human keratinocytes (HaCaT) were used to investigate the mechanism of the antiproliferative effects of vanadyl(IV) sulfate (VOSO4). Treatment of HaCaT cells with VOSO4 inhibited proliferation and induced apoptosis in a dose-dependent manner. Inhibition of proliferation was associated with downregulation of cyclins D1 and E, E2F1, and the cyclin-dependent kinase inhibitors p21Cip1/Waf1 and p27Kip1. Induction of apoptosis correlated with upregulation of the c-fos oncoprotein, changes in the expression of clusterin (CLU), an altered ratio of antiapoptotic to proapoptotic Bcl-2 protein family members, and poly(ADP-ribose) polymerase-1 cleavage. Forced overexpression of c-fos induced apoptosis in HaCaT cells that correlated with secretory CLU downregulation and upregulation of nuclear CLU (nCLU), a pro-death protein. Overexpression of Bcl-2 protected HaCaT cells from vanadium-induced apoptosis, whereas secretory CLU overexpression offered no cytoprotection. In contrast, nCLU sensitized HaCaT cells to apoptosis. Our data suggest that vanadium-mediated apoptosis was promoted by c-fos, leading to alterations in CLU isoform processing and induction of the pro-death nCLU protein. © 2009 FEBS

    A structural approach to the genesis of chrome ores within the Vourinos ophiolite (Greece) : Significance of ductile and brittle deformation processes in the formation of economic ore bodies in oceanic upper mantle peridotites

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    The understanding of ophiolites as hosts to economic\u2013scale chromitite ore deposits requires the integration of research relating their geochemical metallogenesis with studies of the mode and nature of their lithospheric-scale deformation. The Neotethyan Vourinos ophiolite in Northern Greece represents a well-preserved ophiolite complete with sheeted dikes, an in-situ Moho transition zone, and a nearly 8-km-thick upper mantle sequence. Chromitite bodies and sub-economic chrome ores occur throughout its ultramafic section, and above and below the petrological Moho; but, economic concentrations of chromitite are restricted to a region referred to as the \u201cmetalliferous zone\u201d within the upper mantle domain. Ductile deformation, which developed synchronously with mineral re-equilibration and late magmatic activity, re-concentrated chromite grains in mesoscopic fold noses and created massive-textured ore bodies. Re-equilibration of chromite and chromite\u2013olivine grains on microscopic\u2013scale during this ductile deformation produced geochemical patterns that are compatible with strain distribution. Whether re-equilibration varied with strain rate in the mantle lithosphere due to regional heterogeneous conditions, or whether the change in deformation\u2013induced modal distribution of the mineral aggregate more strongly affected the process of re-equilibration is yet to be determined. The richest ore bodies in Vourinos are represented by the schlieren ores of the Xerolivado Mine, and occur as extensive lenses of mylonitic chromitite, marking the highest degree of deformation within the complex. These textures display patterns of re-equilibration geochemical halos and transition from ductile into brittle deformation conditions

    Laser induced autofluorescence for diagnosis of non- melanoma skin cancer

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    Non melanoma skin cancer is one of the most frequent malignant tumors among humans. A non-invasive technique, with high sensitivity and high specificity, would be the most suitable method for basal cell carcinoma (BCC) or other malignancies diagnostics, instead of the well established biopsy and histopathology examination. In the last decades, a non-invasive, spectroscopic diagnostic method was introduced, the laser induced fluorescence (LIF), which could generate an image contrast between different states of skin tissue. The noninvasiveness consists in that this biophotonic method do not require tissue sample excision, what is necessary in histopathology characterization and biochemical analysis of the skin tissue samples, which is worldwide used as an evaluation gold standard. The object of this study is to establish the possibilities of a relatively portable system for laser induced skin autofluorescence to differentiate malignant from nonmalignant skin lesions. Unstained human skin samples, excised from humans undergoing biopsy examination, were irradiated with a Nd: YAG-3 omega laser (lambda= 355 nm, 6 ns), used as an excitation source for the autofluorescence measurements. A portable fiber-based spectrometer was used to record fluorescence spectra of the sites of interest. The ex vivo results, obtained with this spectroscopic technique, were correlated with the histopathology results. After the analysis of the fluorescence spectra of almost 60 skin tissue areas, we developed an algorithm to distinguish different types of malignant lesions, including inflammatory areas. Optimization of the data analysis and potential use of LIF spectroscopy with 355 nm Nd: YAG laser excitation of tissue autofluorescence for clinical applications are discussed

    Platelets transfusion in Greece: Where, when, why? A national survey

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    Background: Platelet transfusion is among the most useful therapeutic tools in modern clinical settings which mean that ensuring an adequate supply is of paramount importance. Aim: The aim of our study was to record the use and wastage of platelet concentrates (PCs) in Greece, so as to come up with evidence-based interventions. Methods: The study was conducted during May and June 2015. We evaluated the use of random-donor platelets (RDPs) and single-donor apheresis platelets (SDPs). We analyzed such parameters as hospital department and diagnosis, indication for transfusion, PCs&apos; age at the time of transfusion, and wastage rate. Results: We used data from 21 hospitals across the country. A total of 12,061 RDPs and 1189 SDPs were transfused, with an average of 4.84 (±2.72) and 1.12 (±2.73) units per episode, respectively. Most patients had been admitted to the internal medicine and hematology departments. The transfusions were mostly given prophylactically, usually in cases of acute leukemia, and mostly on the day before expiration. Wastage rate was 16.75% for RPDs and 2.70% for SDPs, primarily because of the expiration of the use-by date. Conclusions: This is the first national survey regarding platelet transfusion in Greece. Since most patients were admitted in internal medicine and hematology departments, we recommend that the staff of the abovementioned departments should undergo training on contemporary transfusion guidelines. Platelet discard rate could further be lowered through the centralization of inventory management along with the extension of the lifetime of PCs by means of emerging technologies. © 2020 Asian Journal of Transfusion Science
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