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  • 04.03. Geodesy  (2)
  • Mixing
  • Ocean
  • MDPI  (3)
  • American Geophysical Union  (1)
  • MDPI Publishing
  • 2020-2023  (4)
  • 2021  (4)
  • 1
    Publikationsdatum: 2021-12-22
    Beschreibung: The comparison between crustal stress and surface strain azimuthal patterns has provided new insights into several complex tectonic settings worldwide. Here, we performed such a comparison for Egypt taking into account updated datasets of seismological and geodetic observations. In north-eastern Egypt, the stress field shows a fan-shaped azimuthal pattern with a WNW–ESE orientation on the Cairo region, which progressively rotated to NW–SE along the Gulf of Aqaba. The stress field shows a prevailing normal faulting regime, however, along the Sinai/Arabia plate boundary it coexists with a strike–slip faulting one (σ1 ≅ σ2 〉 σ3), while on the Gulf of Suez, it is characterized by crustal extension occurring on near-orthogonal directions (σ1 〉 σ2 ≅ σ3). On the Nile Delta, the maximum horizontal stress (SHmax) pattern shows scattered orientations, while on the Aswan region, it has a WNW–ESE strike with pure strike–slip features. The strain-rate field shows the largest values along the Red Sea and the Sinai/Arabia plate boundary. Crustal stretching (up to 40 nanostrain/yr) occurs on these areas with WSW–ENE and NE–SW orientations, while crustal contraction occurs on northern Nile Delta (10 nanostrain/yr) and offshore (~35 nanostrain/yr) with E–W and N–S orientations, respectively. The comparison between stress and strain orientations over the investigated area reveals that both patterns are near-parallel and driven by the same large-scale tectonic processes.
    Beschreibung: This research was partially funded by the Programa Operativo FEDER Andalucía 2014-2020—A call made by the University of Jaén 2018.
    Beschreibung: Published
    Beschreibung: 1398
    Beschreibung: 2T. Deformazione crostale attiva
    Beschreibung: JCR Journal
    Schlagwort(e): strain ; stress ; GNSS ; Egypt ; 04.03. Geodesy ; 04. Solid Earth ; 04.06. Seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2021-12-23
    Beschreibung: A comparative analysis of geodetic versus seismic moment-rate estimations makes it possible to distinguish between seismic and aseismic deformation, define the style of deformation, and also to reveal potential seismic gaps. This analysis has been performed for Egypt where the present-day tectonics and seismicity result from the long-lasting interaction between the Nubian, Eurasian, and Arabian plates. The data used comprises all available geological and tectonic information, an updated Poissonian earthquake catalog (2200 B.C.–2020 A.D.) including historical and instrumental datasets, a focal-mechanism solutions catalog (1951–2019), and crustal geodetic strains from Global Navigation Satellite System (GNSS) data. The studied region was divided into ten (EG-01 to EG-10) crustal seismic sources based mainly on seismicity, focal mechanisms, and geodetic strain characteristics. The delimited seismic sources cover the Gulf of Aqaba–Dead Sea Transform Fault system, the Gulf of Suez–Red Sea Rift, besides some potential seismic active regions along the Nile River and its delta. For each seismic source, the estimation of seismic and geodetic moment-rates has been performed. Although the obtained results cannot be considered to be definitive, among the delimited sources, four of them (EG-05, EG-06, EG-08, and EG-10) are characterized by low seismic-geodetic moment-rate ratios (〈20%), reflecting a prevailing aseismic behavior. Intermediate moment-rate ratios (from 20% to 60%) have been obtained in four additional zones (EG-01, EG-04, EG-07, and EG-09), evidencing how the seismicity accounts for a minor to a moderate fraction of the total deformational budget. In the other two sources (EG-02 and EG-03), high seismic-geodetic moment-rates ratios (〉60%) have been observed, reflecting a fully seismic deformation
    Beschreibung: This research has been partially funded in the frame of the Programa Operativo FEDER Andalucía 2014–2020-call made by the University of Jaén, 2018.
    Beschreibung: Published
    Beschreibung: 7836
    Beschreibung: 2T. Deformazione crostale attiva
    Beschreibung: JCR Journal
    Schlagwort(e): Seismicity ; GNSS ; Strain ; seismic hazard ; Egypt ; 04. Solid Earth ; 04.03. Geodesy ; 04.06. Seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2022-10-21
    Beschreibung: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Warner, J. C., Geyer, W. R., Ralston, D. K., & Kalra, T. Using tracer variance decay to quantify variability of salinity mixing in the Hudson River Estuary. Journal of Geophysical Research: Oceans, 125(12), (2020): e2020JC016096, https://doi.org/10.1029/2020JC016096.
    Beschreibung: The salinity structure in an estuary is controlled by time‐dependent mixing processes. However, the locations and temporal variability of where significant mixing occurs is not well‐understood. Here we utilize a tracer variance approach to demonstrate the spatial and temporal structure of salinity mixing in the Hudson River Estuary. We run a 4‐month hydrodynamic simulation of the tides, currents, and salinity that captures the spring‐neap tidal variability as well as wind‐driven and freshwater flow events. On a spring‐neap time scale, salinity variance dissipation (mixing) occurs predominantly during the transition from neap to spring tides. On a tidal time scale, 60% of the salinity variance dissipation occurs during ebb tides and 40% during flood tides. Spatially, mixing during ebbs occurs primarily where lateral bottom salinity fronts intersect the bed at the transition from the main channel to adjacent shoals. During ebbs, these lateral fronts form seaward of constrictions located at multiple locations along the estuary. During floods, mixing is generated by a shear layer elevated in the water column at the top of the mixed bottom boundary layer, where variations in the along channel density gradients locally enhance the baroclinic pressure gradient leading to stronger vertical shear and more mixing. For both ebb and flood, the mixing occurs at the location of overlap of strong vertical stratification and eddy diffusivity, not at the maximum of either of those quantities. This understanding lends a new insight to the spatial and time dependence of the estuarine salinity structure.
    Beschreibung: This study was funded through the Coastal Model Applications and Field Measurements Project and the Cross‐shore and Inlets Project, US Geological Survey Coastal Marine Hazards and Resources Program. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US Government.
    Schlagwort(e): Hudson River Estuary ; Mixing ; Numerical modeling ; Tracer variance
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2022-10-20
    Beschreibung: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Blevins, M. G., Allen, H. L., Colson, B. C., Cook, A.-M., Greenbaum, A. Z., Hemami, S. S., Hollmann, J., Kim, E., LaRocca, A. A., Markoski, K. A., Miraglia, P., Mott, V. L., Robberson, W. M., Santos, J. A., Sprachman, M. M., Swierk, P., Tate, S., Witinski, M. F., Kratchman, L. B., & Michel, A. P. M. Field-portable microplastic sensing in aqueous environments: a perspective on emerging techniques. Sensors, 21(10), (2021): 3532, https://doi.org/10.3390/s21103532.
    Beschreibung: Microplastics (MPs) have been found in aqueous environments ranging from rural ponds and lakes to the deep ocean. Despite the ubiquity of MPs, our ability to characterize MPs in the environment is limited by the lack of technologies for rapidly and accurately identifying and quantifying MPs. Although standards exist for MP sample collection and preparation, methods of MP analysis vary considerably and produce data with a broad range of data content and quality. The need for extensive analysis-specific sample preparation in current technology approaches has hindered the emergence of a single technique which can operate on aqueous samples in the field, rather than on dried laboratory preparations. In this perspective, we consider MP measurement technologies with a focus on both their eventual field-deployability and their respective data products (e.g., MP particle count, size, and/or polymer type). We present preliminary demonstrations of several prospective MP measurement techniques, with an eye towards developing a solution or solutions that can transition from the laboratory to the field. Specifically, experimental results are presented from multiple prototype systems that measure various physical properties of MPs: pyrolysis-differential mobility spectroscopy, short-wave infrared imaging, aqueous Nile Red labeling and counting, acoustophoresis, ultrasound, impedance spectroscopy, and dielectrophoresis.
    Beschreibung: We greatly thank our funding agencies: Gerstner Philanthropies (to A.P.M.M.), the Richard Saltonstall Charitable Foundation (to A.P.M.M.), and the Wallace Research Foundation (to A.P.M.M. and S.S.H.). Funding for M.G.B. was provided by a Draper Fellowship and to B.C.C. by an MIT Martin Fellowship. Draper thanks EPA region 9 for their partnership and support through a Cooperative Research and Development Agreement, an industry/government agreement regarding funding and personnel contributions of time and expertise.
    Schlagwort(e): Microplastics ; Plastic pollution ; Sensors ; Analytical chemistry ; Environment ; Water ; Ocean ; Marine pollution ; Polymers ; Freshwater ; Aqueous solutions
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Standort Signatur Erwartet Verfügbarkeit
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