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  • 1
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    Swiss-AlpArray temporary broadband seismic stations deployment and noise characterization (2018)
    Details
    Publication Date: 2020-10-26
    Description: Abstract. AlpArray is a large collaborative seismological project in Europe that includes more than 50 research institutes and seismological observatories. At the heart of the project is the collection of top-quality seismological data from a dense network of broadband temporary seismic stations, in compliment to the existing permanent networks, that ensures a homogeneous station coverage of the greater Alpine region. This Alp Array Seismic Network (AASN) began operation in January 2016 and will have a duration of at least 2 years. In this work we report the Swiss contribution to the AASN, we concentrate on the site selection process, our methods for stations installation, data quality and data management. We deployed 27 temporary broadband stations equipped with STS-2 and Trillium Compact 120 s sensors. The deployment and maintenance of the temporary stations across 5 countries is managed by ETH Zurich and it is the result of a fruitful collaboration between five institutes in Europe.
    Description: Published
    Description: 15–29
    Description: 1IT. Reti di monitoraggio
    Description: JCR Journal
    Keywords: 05.04. Instrumentation and techniques of general interest ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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    PAPER (OA)
  • 2
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    Arrival angles of teleseismic fundamental mode Rayleigh waves across the the AlpArray (2019)
    Details
    Publication Date: 2020-11-30
    Description: The dense AlpArray network allows studying seismic wave propagation with high spatial resolution. Here we introduce an array approach to measure arrival angles of teleseismic Rayleigh waves. The approach combines the advantages of phase correlation as in the two-station method with array beamforming to obtain the phase-velocity vector. 20 earthquakes from the first two years of the AlpArray project are selected, and spatial patterns of arrival-angle deviations across the AlpArray are shown in maps, depending on period and earthquake location. The cause of these intriguing spatial patterns is discussed. A simple wave-propagation modelling example using an isolated anomaly and a Gaussian beam solution suggests that much of the complexity can be explained as a result of wave interference after passing a structural anomaly along the wave paths. This indicates that arrival-angle information constitutes useful additional information on the Earth structure, beyond what is currently used in inversions.
    Description: Published
    Description: 115–144
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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    PAPER (OA)
  • 3
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    The AlpArray Seismic Network: A Large-Scale European Experiment to Image the Alpine Orogen (2019)
    Details
    Publication Date: 2019-12-05
    Description: The AlpArray programme is a multinational, European consortium to advance our understanding of orogenesis and its relationship to mantle dynamics, plate reorganizations, surface processes and seismic hazard in the Alps–Apennines–Carpathians–Dinarides orogenic system. The AlpArray Seismic Network has been deployed with contributions from 36 institutions from 11 countries to map physical properties of the lithosphere and asthenosphere in 3D and thus to obtain new, high-resolution geophysical images of structures from the surface down to the base of the mantle transition zone. With over 600 broadband stations operated for 2 years, this seismic experiment is one of the largest simultaneously operated seismological networks in the academic domain, employing hexagonal coverage with station spacing at less than 52 km. This dense and regularly spaced experiment is made possible by the coordinated coeval deployment of temporary stations from numerous national pools, including ocean-bottom seismometers, which were funded by different national agencies. They combine with permanent networks, which also required the cooperation of many different operators. Together these stations ultimately fill coverage gaps. Following a short overview of previous large-scale seismological experiments in the Alpine region, we here present the goals, construction, deployment, characteristics and data management of the AlpArray Seismic Network, which will provide data that is expected to be unprecedented in quality to image the complex Alpine mountains at depth.
    Description: Published
    Description: 1009–1033
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Seismology ; Alps ; Seismic network ; Geodynamics ; Seismic imaging ; Mountain building
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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    PAPER (OA)
  • 4
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    AlpArray in Hungary: temporary and permanent seismological networks in the transition zone between the Eastern Alps and the Pannonian basin (2019)
    Details
    Publication Date: 2019-03-07
    Description: In the last few decades dense large-scale seismic networks showed their importance in studying the structure of the lithosphere and the upper mantle. The better understanding of the Apennines–Alps–Carpathian–Dinarides system is the main target of the AlpArray European international initiative in which more than 50 institutes are involved. The core of AlpArray is the AlpArray Seismic Network (AASN). With its 􏰖 600 broadband seismic stations ( 􏰖 280 of which are temporary) the AASN is, so far, the largest passive seismic experiment in Europe. The MTA CSFK Geodetic and Geophysical Insti- tute, as a Core Member of the AlpArray project, contributes to the AlpArray Seismic Network with its entire permanent network as well as with 11 temporary broadband seismic stations deployed in Western Hungary. Three additional station equipment were provided by the Swiss-AlpArray SINERGIA program. The average station distance together with the permanent stations is around 40 km in the area of interest. The temporary network has been installed between December 2015 and July 2016 and the planned operation period is 3 years. In this paper we describe the characteristics of the 29 per- manent and temporary stations, introducing not only the equipment, but the location, housing and geological setting, as well. We present median power spectral density curves in order to characterise the noise conditions at each station.
    Description: Hungarian Academy of Sciences (Grants EU-04/2014, EU-07/2015); Swiss-AlpArray SINERGIA Project CRSII2_154434/1 by the Swiss National Science Foundation (SNSF)
    Description: Published
    Description: 221–245
    Description: 1IT. Reti di monitoraggio
    Description: 5IT. Osservatori
    Description: JCR Journal
    Keywords: AlpArray ; Temporary seismic network ; Seismic noise ; Hungarian National Seismological Network ; Pannonian basin ; Solid Earth ; Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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  • 5
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    Shear wave splitting in the Alpine region (2022)
    Oxford University Press - The Royal Astronomical Society
    Details
    Publication Date: 2022-04-21
    Description: To constrain seismic anisotropy under and around the Alps in Europe, we study SKS shear wave splitting from the region densely covered by the AlpArray seismic network. We apply a technique based on measuring the splitting intensity, constraining well both the fast orientation and the splitting delay. Four years of teleseismic earthquake data were processed, from 723 temporary and permanent broad-band stations of the AlpArray deployment including ocean-bottom seismometers, providing a spatial coverage that is unprecedented. The technique is applied automatically (without human intervention), and it thus provides a reproducible image of anisotropic structure in and around the Alpine region. As in earlier studies, we observe a coherent rotation of fast axes in the western part of the Alpine chain, and a region of homogeneous fast orientation in the Central Alps. The spatial variation of splitting delay times is particularly interesting though. On one hand, there is a clear positive correlation with Alpine topography, suggesting that part of the seismic anisotropy (deformation) is caused by the Alpine orogeny. On the other hand, anisotropic strength around the mountain chain shows a distinct contrast between the Western and Eastern Alps. This difference is best explained by the more active mantle flow around the Western Alps. The new observational constraints, especially the splitting delay, provide new information on Alpine geodynamics. © 2021 The Author(s) 2021. Published by Oxford University Press on behalf of The Royal Astronomical Society.
    Description: Published
    Description: 1996–2015
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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    PAPER (OA)
  • 6
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    Unknown
    The AlpArray Seismic Network: A Large-Scale European Experiment to Image the Alpine Orogen (2018)
    Springer
    In:  Surveys in Geophysics, 39 (5). pp. 1009-1033.
    Details
    Publication Date: 2021-02-08
    Description: The AlpArray programme is a multinational, European consortium to advance our understanding of orogenesis and its relationship to mantle dynamics, plate reorganizations, surface processes and seismic hazard in the Alps–Apennines–Carpathians–Dinarides orogenic system. The AlpArray Seismic Network has been deployed with contributions from 36 institutions from 11 countries to map physical properties of the lithosphere and asthenosphere in 3D and thus to obtain new, high-resolution geophysical images of structures from the surface down to the base of the mantle transition zone. With over 600 broadband stations operated for 2 years, this seismic experiment is one of the largest simultaneously operated seismological networks in the academic domain, employing hexagonal coverage with station spacing at less than 52 km. This dense and regularly spaced experiment is made possible by the coordinated coeval deployment of temporary stations from numerous national pools, including ocean-bottom seismometers, which were funded by different national agencies. They combine with permanent networks, which also required the cooperation of many different operators. Together these stations ultimately fill coverage gaps. Following a short overview of previous large-scale seismological experiments in the Alpine region, we here present the goals, construction, deployment, characteristics and data management of the AlpArray Seismic Network, which will provide data that is expected to be unprecedented in quality to image the complex Alpine mountains at depth.
    Type: Article , PeerReviewed
    Format: text
    Format: video
    Format: other
    Format: other
    Format: other
    Format: text
    DOI: 10.1007/s10712-018-9472-4
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    Unknown
    Arrival angles of teleseismic fundamental mode Rayleigh waves across the AlpArray (2019)
    Wiley
    In:  Geophysical Journal International, 218 (1). pp. 115-144.
    Details
    Publication Date: 2022-01-31
    Description: The dense AlpArray network allows studying seismic wave propagation with high spatial resolution. Here we introduce an array approach to measure arrival angles of teleseismic Rayleigh waves. The approach combines the advantages of phase correlation as in the two-station method with array beamforming to obtain the phase-velocity vector. 20 earthquakes from the first two years of the AlpArray project are selected, and spatial patterns of arrival-angle deviations across the AlpArray are shown in maps, depending on period and earthquake location. The cause of these intriguing spatial patterns is discussed. A simple wave-propagation modelling example using an isolated anomaly and a Gaussian beam solution suggests that much of the complexity can be explained as a result of wave interference after passing a structural anomaly along the wave paths. This indicates that arrival-angle information constitutes useful additional information on the Earth structure, beyond what is currently used in inversions.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1093/gji/ggz081
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
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    Unknown
    Ambient-noise tomography of the wider Vienna Basin region (2018)
    Wiley
    In:  Geophysical Journal International, 215 (1). pp. 102-117.
    Details
    Publication Date: 2021-02-08
    Description: We present a new 3-D shear-velocity model for the top 30 km of the crust in the wider Vienna Basin region based on surface waves extracted from ambient-noise cross-correlations. We use continuous seismic records of 63 broad-band stations of the AlpArray project to retrieve interstation Green’s functions from ambient-noise cross-correlations in the period range from 5 to 25 s. From these Green’s functions, we measure Rayleigh group traveltimes, utilizing all four components of the cross-correlation tensor, which are associated with Rayleigh waves (ZZ, RR, RZ and ZR), to exploit multiple measurements per station pair. A set of selection criteria is applied to ensure that we use high-quality recordings of fundamental Rayleigh modes. We regionalize the interstation group velocities in a 5 km × 5 km grid with an average path density of ∼20 paths per cell. From the resulting group-velocity maps, we extract local 1-D dispersion curves for each cell and invert all cells independently to retrieve the crustal shear-velocity structure of the study area. The resulting model provides a previously unachieved lateral resolution of seismic velocities in the region of ∼15 km. As major features, we image the Vienna Basin and Little Hungarian Plain as low-velocity anomalies, and the Bohemian Massif with high velocities. The edges of these features are marked with prominent velocity contrasts correlated with faults, such as the Alpine Front and Vienna Basin transfer fault system. The observed structures correlate well with surface geology, gravitational anomalies and the few known crystalline basement depths from boreholes. For depths larger than those reached by boreholes, the new model allows new insight into the complex structure of the Vienna Basin and surrounding areas, including deep low-velocity zones, which we image with previously unachieved detail. This model may be used in the future to interpret the deeper structures and tectonic evolution of the wider Vienna Basin region, evaluate natural resources, model wave propagation and improve earthquake locations, among others.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1093/gji/ggy259
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
    facet.materialart.
    Unknown
    Crustal Thinning From Orogen to Back-Arc Basin: The Structure of the Pannonian Basin Region Revealed by P-to-S Converted Seismic Waves (2021)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-02-07
    Description: We present the results of P-to-S receiver function analysis to improve the 3D image of the sedimentary layer, the upper crust, and lower crust in the Pannonian Basin area. The Pannonian Basin hosts deep sedimentary depocentres superimposed on a complex basement structure and it is surrounded by mountain belts. We processed waveforms from 221 three-component broadband seismological stations. As a result of the dense station coverage, we were able to achieve so far unprecedented spatial resolution in determining the velocity structure of the crust. We applied a three-fold quality control process; the first two being applied to the observed waveforms and the third to the calculated radial receiver functions. This work is the first comprehensive receiver function study of the entire region. To prepare the inversions, we performed station-wise H-Vp/Vs grid search, as well as Common Conversion Point migration. Our main focus was then the S-wave velocity structure of the area, which we determined by the Neighborhood Algorithm inversion method at each station, where data were sub-divided into back-azimuthal bundles based on similar Ps delay times. The 1D, nonlinear inversions provided the depth of the discontinuities, shear-wave velocities and Vp/Vs ratios of each layer per bundle, and we calculated uncertainty values for each of these parameters. We then developed a 3D interpolation method based on natural neighbor interpolation to obtain the 3D crustal structure from the local inversion results. We present the sedimentary thickness map, the first Conrad depth map and an improved, detailed Moho map, as well as the first upper and lower crustal thickness maps obtained from receiver function analysis. The velocity jump across the Conrad discontinuity is estimated at less than 0.2 km/s over most of the investigated area. We also compare the new Moho map from our approach to simple grid search results and prior knowledge from other techniques. Our Moho depth map presents local variations in the investigated area: the crust-mantle boundary is at 20–26 km beneath the sedimentary basins, while it is situated deeper below the Apuseni Mountains, Transdanubian and North Hungarian Ranges (28–33 km), and it is the deepest beneath the Eastern Alps and the Southern Carpathians (40–45 km). These values reflect well the Neogene evolution of the region, such as crustal thinning of the Pannonian Basin and orogenic thickening in the neighboring mountain belts.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Format: text
    Format: archive
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
    facet.materialart.
    Unknown
    Shear wave splitting in the Alpine region (2021)
    Oxford University Press
    Details
    Publication Date: 2024-02-07
    Description: To constrain seismic anisotropy under and around the Alps in Europe, we study SKS shear wave splitting from the region densely covered by the AlpArray seismic network. We apply a technique based on measuring the splitting intensity, constraining well both the fast orientation and the splitting delay. Four years of teleseismic earthquake data were processed, from 723 temporary and permanent broad-band stations of the AlpArray deployment including ocean-bottom seismometers, providing a spatial coverage that is unprecedented. The technique is applied automatically (without human intervention), and it thus provides a reproducible image of anisotropic structure in and around the Alpine region. As in earlier studies, we observe a coherent rotation of fast axes in the western part of the Alpine chain, and a region of homogeneous fast orientation in the Central Alps. The spatial variation of splitting delay times is particularly interesting though. On one hand, there is a clear positive correlation with Alpine topography, suggesting that part of the seismic anisotropy (deformation) is caused by the Alpine orogeny. On the other hand, anisotropic strength around the mountain chain shows a distinct contrast between the Western and Eastern Alps. This difference is best explained by the more active mantle flow around the Western Alps. The new observational constraints, especially the splitting delay, provide new information on Alpine geodynamics.
    Type: Article , PeerReviewed
    Format: text
    Format: archive
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
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