AdriaArray - Data analysis and research

Collaborative Research Groups (CRGs)

According to the Memorandum of Collaboration (MoC), the scientific work is accomplished by so-called Collaborative Research Groups (CRGs).

  • CRGs are suggested by participants,

  • CRGs work independently,

  • Themes of CRGs are discussed and agreed upon by the AdASG Steering Committee,

  • CRGs report on activities at AdASG Workshops,

  • CRGs must consist of researchers from at least two AdASG members and from different countries,

  • Participants may join one or several CRGs,

  • If possible, the individual CRGs are coordinated by an experienced researcher and an early career scientist,

  • Participants in CRGs may change any time upon notice to the coordinators of the CRGs.

Working Group 5 of the AdASG entitled ‘Scientific co-operation’ will coordinate and support the establishment of CRGs. First suggestions of the CRGs have been proposed during the second international workshop in Potsdam, third international workshop in Dubrovnik & EGU 2023 AdriaArray Splinter meeting.

Now, AdriaArray participants are invited to contact the initial contacts of CRGs (given below) to join one or several Collaborative Research Groups. Initial contacts will organize the reviews of the topic, the elections of chairs and co-chairs, and maintain a list of interested participants.

Initial contacts will also report the outcome of these discussions to Working Group 5 of the AdASG. Suggestions of CRGs will be reviewed by Working Group 5 before presentation to and approval by the Steering Committee.

In the following we summarize the discussion on potential topics of CRGs.

CRG ‘Seismicity’

  • Membership secretary: F. Tilmann.

  • Chair: E. Sokos.

  • Co-chair: G. Petersen.

  • Main topics are Event detection & location, determination of source mechanisms as well as statistic analysis and seismotectonics.

The CRG Seismicity is split into four subgroups to coordinate the collaborative work:

  1. Survey of monitoring practices at national agencies: G. Rossi & Z. Roumeloti, F. Tilmann.

  2. Parametric data exchange with EMSC, station naming and reporting: C. Papazachos & C. Evangelidis.

  3. Machine learning for seismicity detection and location & crowd processing: D Sindija & F. Tilmann.

  4. Moment tensors: G. Petersen & E. Sokos. The AdriaArray Seismic Network produced a huge increase in available real time data for source studies. The moment tensor subgroup aims in the use of this data, in real time moment tensor retrieval applications, as well as in detailed source studies of moderate and large events in the area.

CRG ‘Body wave tomography’

Body wave traveltimes

  • Intitial contacts: P. De Gori.

  • The large station array and huge high-quality data stream, produced earlier by the AlpArray and now by AdriaArray Seismic Networks, provide a rich and unique dataset for body wave tomography studies. To optimize the exploitation of the size and quality of these dataset we need to employ semi- or fully automated picking procedures able to reproduce in the best way the careful, handy re-picked tasks of the experienced seismologists.

  • This activity could include:

    1. surveying and benchmarking of the existing automated picking tools for regional and teleseismic phases;

    2. surveying, checking the consistency and sharing the available carefully picked datasets that can be used for comparison and/or learning phases with automated picking procedures;

    3. comparing picks for a number (to be decided) of selected earthquakes at all AdriaArray stations;

    4. optimizing automatic picking algorithms and possibly providing training and application on the use of software tools;

    5. creating a common dataset for a AdA sub region to compare different picking and different inversion codes (as requested by point 3 below).

Synthetic resolution tests of body wave tomography

  • Intitial contact: C. Estève.

  • We propose to investigate the crust and upper mantle velocity structure underlying the AdriaArray seismic network. In order to achieve this, we need to test different parametrizations and approaches for a subset of the AdriaArray dataset through the extensive use of synthetic resolution tests (spike test, checkerboard test, structural test,…).

CRG ‘Forward modeling and waveform inversion’

  • Chair: H. Keers.

  • Co-chair: S. Chevrot.

  • The main goal of the CRG on Modeling body wave propagation is to systematically compare the various seismic modeling methods that are used, or have the potential to be used, in regional seismology. Related subgoals are to build suitable velocity models for these modeling methods (using existing tomographic models and/or input from the geodynamic CRG), the observations and modeling of various seismic phases (travel times, waveforms, splitting parameters) and the use of these modeling methods in the computation of sensitivity functions and inversions.

This CRG aims to foster collaborations on methodological developments to improve regional-scale FWI imaging by exploiting both body and surface waves. Another objective of this CRG is to provide tools and methods to compute synthetic seismograms in 3D analogues of continental and oceanic subduction zones. These synthetic seismograms will be useful for testing the different tomographic approaches that will be implemented on the AdriaArray datasets. Finally, this CRG will also work on the application of FWI approaches on several focused targets such as the Vrancea region, the Dinarides and the Hellenic subduction. All AdriaArray participants interested in any aspect of these different initiatives (regarding data, methods, geological and geodynamic interpretation, etc…) are invited to join this CRG.

CRG ‘Receiver functions’

  • Chairs: G. Georgieva.

  • Co-chair: S. Rondenay & J. Stipčević

  • This CRG will provide support to AdriaArray members who work on receiver function studies as well as those who want to use receiver function results in their research. In terms of methodologies, the CRG will provide access to harmonized receiver function analysis tools and training on how to use these. It will also serve as a platform to share software and tips on data analysis, and to carry out community-based benchmarking tests. In terms of imaging targets, the CRG will help coordinate efforts to avoid potential overlaps and foster collaborations. At the end of the project, the CRG will produce a harmonized set of receiver function products for the entire AdriaArray network.

CRG ‘Ambient noise database’

  • Chair: A. Obermann.

  • Co-chair: Irene Molinari.

  • In a joined effort, we will deconvolve and downsample the continuous seismic data from the various subnetworks participating in AdriaArray. This data (around 3-4 TB) will be made available to anybody interested in computing cross-correlation functions for various purposes from mapping ambient noise sources to tomography or time lapse monitoring.

CRG ‘Surface wave phase tomography’

  • Chair: E. Kästle.

  • Co-chair: A. Sergeant, L. Petrescu.

  • This CRG aims at gathering multiple methodologies that use surface waves (Rayleigh and/or Love) for 2D and 3D imaging of the crustal and upper mantle structure in the region. Following traditional frameworks of surface wave tomography (SWT), the work handled within this CRG targets four main collaborative tasks:

    1. the construction of reliable surface wave datasets from earthquake data and/or ambient noise,

    2. the measurement of the surface wave phase/group travel times and amplitudes for constructing 2D maps of isotropic (and anisotropic) Rayleigh/Love velocities,

    3. the depth-inversion of phase (and group) velocity dispersion curves, and

    4. the joint inversion with other observables. This group provides a platform for setting up and sharing databases, method testing and benchmarking, resolution test analysis, and further discussions on methodological developments. It includes linearized inversion method, Bayesian approaches, Eikonal/Helmholtz tomography, 2D phase velocity map inversions or direct 3D approaches, radial and azimuthal anisotropy and many others.

CRG ‘Body waves from ambient noise’

  • Chair: Y. Lu.

  • Co-chair: .

  • Recent advancements in passive noise interferometry have shown promising results in the retrieval of body waves from noise correlations. This primarily includes various body-wave reflection phases generated by dominant subsurface discontinuities, such as the Basin sediment/bedrock interface, the Moho interface, and the 410-km and 660-km mantle transition zone interfaces. The information that provided is particularly valuable for determining the depth undulations of subsurface discontinuities and can be seamlessly integrated into seismic tomography for a more comprehensive understanding of the deep earth structure. Given its remarkable data quality and data coverage, the AdriaArray seismic network presents an ideal setting for the implementation and development of such cutting-edge seismic techniques.

We are primarily focused on the following objectives:

  1. application of noise body waves for imaging the mantle transition zone interfaces.

  2. application of noise body waves for imaging the Moho interface.

  3. application of noise body waves for imaging the intra-crustal interfaces (e.g., basin bottom).

  4. methodological development for extracting body waves from noise (including reflection phases and direct arrivals).

CRG ‘Ambient Noise Sources (natural and anthropogenic sources, imaging, environmental seismology)’

  • Chair: R. Kramer.

  • Co-chair: L. Wiesenberg.

  • The research group will be split into subgroups to target the following suggested research topics:

    1. The first subgroup will deal with natural noise variation and localization of noise sources. We want to specifically investigate variations depending on e.g., local weather effects like wind or air pressure. Localizing marine noise sources in the marginal seas of the Adriatic region will be investigated using variations of primary, secondary, and local microseism over time.

    2. This subgroup will work on the characterization of urban/anthropogenic sources. We want to find out if there are specific anthropogenic noise sources dominating the ambient noise field in the region (e.g., power plants, rotating machines, …).

    3. Characterization of the ambient noise field of the Danube to understand the ambient noise field and its origin of the second largest river in Europe.

  • The overall goal of this first topic is to gain proper insight into the distribution, strength, variation, and influences on the noise sources and set the basis for further investigations (e.g., monitoring, tomography, …).

All topics require mostly raw data of at least one year, which will be processed by the researcher themselves. Minor topics require ambient noise cross correlations to confirm the orientation of predominant noise sources. For the third research idea it might be necessary to install additional seismic stations.

CRG ‘Measuring shear wave splitting’

  • Chair: S. Pondrelli.

  • Co-chair: .

  • This CRG aims to collect previous measurements in the study region to identify gaps to be filled with new data. New measurements can give the opportunity to have benchmarking methods & training. We expect to produce new splitting directions and anisotropy intensity values, obtained using various seismic phases with the perspective to reach joint inversions and interpretations of seismic anisotropy. An important goal indeed is the interaction with the other CRGs focusing on body and surface waves as well as receiver functions to share our new data.

CRG ‘Engineering Seismology’

CRG ‘Linking geophysical observables with geodynamics’

  • Chair: T. Meier.

  • Co-chair: L. Petrescu.

  • Using AdriaArray data, the interior of the Adriatic plate and its margins, slabs and slab windows as well as upper mantle flow will be imaged to clarify open questions regarding the driving forces of plate deformation and kinematics. To test the resolution capabilities of imaging methods and to design input models for numerical geodynamic experiments, at first existing hypotheses of lithospheric and upper mantle structure are to be described in digital form. Hypotheses of slabs and slab windows along the margins of the Adriatic plate (Alps, Apennines, Calabrian Arc, Carpathians, Dinarides, Hellenides) are to be reviewed and discussed based on available observables like seismicity, Moho maps, tomographic models, and receiver function images. Different hypotheses for the slab interface are to be provided in digital format. For these hypotheses, consistent 3D models of various parameters (seismic velocities, temperatures, densities, composition, viscosity) are to be set up using thermomechanical modelling. They form the basis for numerical geodynamic modelling of quantities like plate kinematics, stress, strain fields or exhumation rates that are to be compared with field observations and the geological record. Experts from various relevant disciplined are invited to join the CRG.