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The Multi-scale Laboratories (MSL) are a network of European laboratories bringing together the scientific fields of analogue modeling, paleomagnetism, experimental rock and melt physics, geochemistry and microscopy. MSL is one of nine (see below) Thematic Core Services (TCS) of the European Plate Observing System (EPOS). The overarching goal of EPOS is to establish a comprehensive multidisciplinary research platform for the Earth sciences in Europe. It aims at facilitating the integrated use of data, models, and facilities, from both existing and new distributed pan European Research Infrastructures, allowing open access and transparent use of data. The TCS MSL network allows researchers to collaborate with other labs and scientists. By becoming part of the rapidly growing TCS MSL network, new laboratories are offered a platform to showcase their research data output, laboratory equipment and information, and the opportunity to open laboratories to guest researchers through the Transnational Access (TNA) program. The EPOS Multi-scale laboratories offer researchers a fully operational data publication chain tailored to the specific needs of laboratory research, from a bespoke metadata editor, through dedicated, (domain-specific) data repositories, to the MSL Portal showcasing these citable data publications. During this process the data publications are assigned with digital object identidiers (DOI), published with open licenses (e.g. CC BY 4.0) and described with standardized and machine-readable rich metadata (following the FAIR Principles to make research data Findable, Accessible, Interoperable and Reusable. The TCS MSL is currently working on linking these data publications to the EPOS Central Portal1, the main discovery and access point for European multi-disciplinary data, and on increasing the number of connected data repositories. info:eu-repo/semantics/publishedVersion

International audience; EPOS, the European Plate Observing System, is a unique e-infrastructure and collaborative environment for the solid earth science community in Europe and beyond (https://www.epos-eu.org/). A wide range of world-class experimental (analogue modelling and rock and melt physics) and analytical (paleomagnetic, geochemistry, microscopy) laboratory infrastructures are concerted in a “Thematic Core Service” (TCS) labelled “Multi-scale Laboratories” (MSL) (https://www.epos-eu.org/tcs/multi-scale-laboratories). Setting up mechanisms allowing for sharing metadata, data, and experimental facilities has been the main target achieved during the EPOS implementation phase. The TCS Multi-scale Laboratories offers coordination of the laboratories’ network, data services, and Trans-National access to laboratory facilities.In the framework of data services, TCS Multi-Scale Laboratories promotes FAIR (Findable-Accessible-Interoperable-Re-Usable) (FAIR) sharing of experimental research data sets through Open Access data publications. Data sets are assigned with digital object identifiers (DOI) and are published under the CC BY license. Data publications are now conventionally citable in scientific journals and develop rapidly into a common bibliometric indicator and research metric. A dedicated metadata scheme (following international standards that are enriched with disciplinary controlled community vocabulary) facilitates ease exploration of the various data sets in a TCS catalogue (https://epos-msl.uu.nl/). Concerning analogue modelling, a growing number of data sets includes analogue material physical and mechanical properties and modelling results (raw data and processed products such as images, maps, graphs, animations, etc.) as well as software (for visualization, monitoring and analysis). The main geoscience data repository is currently GFZ Data Services, hosted at GFZ German Research Centre for Geosciences (https://dataservices.gfz-potsdam.de), but others are planned to be implemented within the next years.In the framework of Trans-National access (TNA), TCS Multi-scale laboratories’ facilities are accessible to any researchers, creating new opportunities for synergy, collaboration and scientific innovation, according to TNAtrans-national access rules. TNA can be realized in the form of physical access (on-site experimenting and analysis), remote service (sample analysis) and virtual access (remotely operated processing). After three successful TNA calls, the pandemic has forced a moratorium on the TNA program.The EPOS TCS Multiscale Laboratories framework is also providing the foundation for a comprehensive database of rock analogue materials, a dedicated bibliography, and facilitates the organization of community-wide activities (e.g., meetings, benchmarking) to stimulate collaboration among analogue laboratories and the exchange of know-how. Recent examples of these community efforts are also the contributions to the monthly MSL seminars, available on the MSL YouTube channel (https://www.youtube.com/channel/UCVNQFVql_TwcSBqgt3IR7mQ/featured), as well as the Special Issue on basin inversion in Solid Earth that is currently open for submissions (https://www.solid-earth.net/articles_and_preprints/scheduled_sis.html#1160).

The evolution of the Sicily Channel Rift Zone (SCRZ), located south of the Central Mediterranean, is thought to accommodate the regional tectonic stresses of the Calabrian subduction system. It is unclear whether the rifting of the SCRZ is passive from far-field extensional stresses or active from mantle upwelling beneath. To map the structure and dynamics of the region, we measure Rayleigh- and Love-wave phase velocities from ambient seismic noise and invert for an isotropic 3-D shear-velocity and radial anisotropic model. Variations of crustal S-velocities coincide with topographic and tectonic features: slow under high elevation, fast beneath deep sea. The Tyrrhenian Sea has a VSV); areas experiencing compression and subduction-related volcanism have negative anisotropy (VSH

The dynamics of subduction zones is linked to the rise and demise of forearc and backarc sedimentary basins in the overriding plate. Subsidence and uplift rates of these distinct basins are controlled by variations in plate convergence and subduction velocities and determined by the rheological and thermal structure of the lithosphere. In this study we conducted a series of high-resolution 2D numerical models of oceanic subduction and subsequent continental collision. The numerical code 2DELVIS involves erosion, sedimentation, and hydration processes. The models show the evolution of wedge-top basins overlying the accretionary wedge and retro-forearc basins in the continental overriding plate, separated by a forearc high. These forearc regions are affected by repeated compression and extension phases. Higher subsidence rates are recorded in the syncline structure of the retro-forearc basin when the slab dip angle is higher and the subduction interface is stronger. This implies the importance of the slab suction force as the main forcing factor creating up to 3-4 km negative residual topographic signals. Extensional back-arc basins are either localized along inherited weak zones at large distance from the forearc region or are initiated just above the hydrated mantle wedge. Back-arc subsidence is primarily governed by crustal and lithospheric thinning controlled by slab roll-back. Our results are compared with the evolution of the Mediterranean and we classify the Western and Eastern Alboran, Paola and Tyrrhenian, Transylvanian and Pannonian Basins to be genetically similar forearc–backarc basins, respectively.

The Sicily Channel, located on the north-central African plate foreland between Sicily, Tunis and Libya, is characterised by a seismically and volcanically active rift zone. This rift extends for more than 600 km in length offshore from the south of Sardinia to the south-east of Malta. Much of the observations we have today are either limited to the surface and the upper crust, or are broader and deeper from regional seismic tomography, missing important details about the lithospheric structure and dynamics. The project GEOMED (https://geomed-msca.eu) addresses this issue by processing all the seismic data available in the region in order to understand better the geodynamics of the Central Mediterranean. A recently compiled earthquake catalogue for the eastern part of the Sicily Channel Rift Zone (SCRZ) will be presented highlighting offshore active faults in the region, and new results from seismic tomography give an insight of what lies beneath. We measure seismic velocities from across the region using ambient seismic noise recorded on more than 50 stations located on Algeria, Italy (Lampedusa, Linosa, Pantelleria, Sardinia, Sicily), Libya, Malta, and Tunisia. The phase-velocity dispersion curves have periods ranging from 5 to 100 seconds and sample through the entire lithosphere. We find that slow and fast seismic velocities coincide with regional tectonic and topographic features. At short periods, Africa and Italy have slower velocities indicating these areas have thick continental crust in contrast to areas beneath Tyrrhenian and Ionian basins. The central area of the SCRZ has relatively faster velocities suggesting that there is a thinner crust. At longer periods the central area of SCRZ is characterised by slower velocities indicative of warmer temperatures than the surrounding. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 843696., peer-reviewed

Datasets for this article are available in 655 http://hdl.handle.net/20.500.11850/364963 (DOI: 10.3929/ethz-b-000364963)., In this work we study the dynamics of double subduction systems with opposite polarity in adjacent segments. A combined approach of numerical and analog experiments allows us to compare results and exploit the strengths of both methodologies. High‐resolution numerical experiments complement laboratory results by providing quantities difficult to measure in the laboratory such as stress state, flow patterns and energy dissipation. Results show strong asymmetries in the mantle flow that produce in turn asymmetries in the trench and in the downgoing slab deformation. The mantle flow pattern varies with time; the toroidal cells between the plates evolve until merging into one unique cell when the trenches align. In that moment the maximum upward flow is observed close to the trenches. The interaction between the mantle flow produced by each subducting plate makes the rollback processes slower than in a single subduction case. This is consistent with the observed energy dissipation rate that is smaller in the double subduction system than in two single subductions. Moreover, we provide a detailed analysis on the setup and boundary conditions required to numerically reproduce the analog experiments. Boundary conditions at the bottom of the domain are crucial to reproduce their analog counterparts. Numerical results are compared to natural examples of multi‐slab subduction systems in terms of upper mantle seismic anisotropy, relative trench‐retreat velocities and composition of subduction‐related magmatism., This work is part of the PhD Thesis of MP developed under the projects SUBTETIS647 CSIC-201830E039, and AGAUR 2017-SGR-847/2017-SGR-1471. We also thank projects 648 AECT-2018-1-0007 and AECT-2018-3-0007 of the Barcelona Supercomputing Center (BSC649 CNS). JR was supported by the Swiss National Science Foundation (grant number 2-77297-15). 650 SZ thank the funding from AGAUR 2017-SGR-1278, the Agencia Estatal de Investigación 651 project DPI2017-85139-C2-2-R and the European Union project H2020-RISE MATHROCKS 652 GA nº 777778. The grant provided to the Department of Science, Roma Tre University (MIUR653 ITALY Dipartimenti di Eccellenza, ARTICOLO 1, COMMI 314‐337 LEGGE 232/2016) is 654 gratefully acknowledged by F.F.

laboratories and form one of the Thematic Cores Services (TCS) of the European Plate Observing System (EPOS), an ESFRI Landmark and European Research Infrastructure Consortium (ERIC). , . The diversity of experimental and analytical methods employed in such infrastructures reflects the multi-scale nature of the Earth system and is essential for the understanding of its evolution, for the assessment of geo-hazards, and for the sustainable exploitation of geo-resources. The TCS MSL is committed to make Earth science laboratory data FAIR: Findable, Accessible, Interoperable, and Reusable. For this purpose, the TCS MSL has developed an online portal that brings together DOI-referenced data publications from research data repositories related to the TCS MSL context (https://epos-msl.uu.nl/). In addition, the TCS MSL has developed a Trans-national access (TNA) program that allows researchers and research teams to apply for physical or remote access to the participating EPOS MSL laboratories. Access is currently supported by national funding or in-kind contribution. Based on the EPOS Data policy & TNA General Principles, access is regulated by common rules and a transparent policy, including procedures and mechanisms for application, negotiation, proposal evaluation, user feedback, use of laboratory facilities and data curation. Access to EPOS Multi-scale laboratories is a unique opportunity to create new synergy, collaboration and innovation, in a framework of trans-national access rules. Unaffiliated European solid Earth sciences laboratories are welcome and encouraged to join the growing TCS MSL community.

Tsunamigenic earthquakes pose a large hazard in subduction zones, but it is currently unclear in which - if any - tectonic setting they preferentially occur. We compile the Subduction Nature & Interconnected Tsunamigenic earthquake Characteristics (SNITCH) database with parameters on the geodynamics, megathrust seismicity, and tsunami characteristics for tsunamis caused by earthquakes in all subduction zones. We use a bivariate regression analysis to detect possible relationships between the tsunamigenic earthquake characteristics of a subduction zone and its interplate seismicity, as well as its geometric, structural, and kinematic parameters. We focus our analysis on the normalised number of tsunamigenic earthquakes Nt. The bivariate analysis does not reveal any significant correlations between Nt and the seismogenic zone geometry of the megathrust. However, we do find correlations between Nt and the megathrust seismicity and tectonic parameters characterising a subduction zone. We employ a multivariate Fisher analysis on the tectonic parameters to see which combinations best distinguish the subduction zone segments in which relatively many and few tsunamis occurred. We find that the type of margin (i.e., erosional or accretionary), the trench-normal component of the subduction and convergence velocity, the amount of sediments at the trench and the roughness of the incoming plate are the most important parameters to achieve this. Therefore, tsunamigenic earthquakes may be more prone to occur in tectonic settings where plates subduct relatively fast beneath a sediment-starved, erosional margin. A complex, shallow subduction interface, characterised by multiple faults and fractures that arise at a margin with little trench sediments to smooth subducting plate topography, could account for the larger number of tsunamigenic earthquakes. These results could have implications for hazard assessment.

International audience; Since several decades, the processes allowing for the subduction of the continental lithosphere less dense than the mantle in a collision context have been widely explored, but models that are based upon the premise that slab pull is the prominent driver of plate tectonics fail. The India–Asia collision, where several episodes of continental subduction have been documented, constitute a case study for alternative views. One of these episodes occurred in the early collision time within the Asian plate where continental lithosphere not attached to any oceanic lithosphere subducted southward in front of the Indian lithosphere during its northward subduction that followed the oceanic subduction of the Tethys ocean. This process, known as collisional subduction, has a counter-intuitive behavior since the subduction is not driven by slab pull. It has been speculated that the mantle circulation can play an important role in triggering collisional subduction but a detailed, qualitative analysis of it is not available, yet. In this work we explore the southward subduction dynamics of the Asian lithosphere below Tibet by means of analogue experiments with the aim to highlight how the mantle circulation induces or responds to collisional subduction. We found that during the northward oceanic subduction (analogue of Tethys subduction) attached to the indenter (Indian analogue), the main component of slab motion is driven vertically by its negative buoyancy, while the trench rolls back. In the mantle the convective pattern consists in a pair of wide convective cells on both sides of the slab. But when the indenter starts to bend and plunge in the mantle, trench motion reverses. Its advance transmits the far field forces to two upper plates (Asian analogues). The more viscous frontal plate thickens, and the less viscous hinterland plate, which is attached to the back wall of the box, subducts. During this transition, a pair of sub-lithospheric convective cells is observed on both sides of the Asian analogue slab, driven by the shortening of the frontal plate. It favors the initiation of the backwall plate subduction. Such subduction is maintained during the entire collision by a wide cell with a mostly horizontal mantle flow below Tibet, passively advecting the Asian analogue slab. Experimental results suggest that once the tectonic far-field force related to the forward horizontal motion becomes dominant upon the buoyancy forces, trench advancing and the transmission of the tectonic force to the upper and backwall plates are promoted. This peculiar condition triggers the subduction of the backwall plate, despite it is light and buoyant.

The evolution of the Gibraltar Arc and the whole western Mediterranean region is still highly debated by geologists and geophysicists. This work is based on a recent geodynamic model proposing a lateral change in subduction polarity of the Ligurian Tethys oceanic domain to explain its formation and evolution since 46 Myr. The aim of this study is to reproduce and analyze the curvature evolution of the Rif-Gibraltar-Betic slab in such tectonic scenario by means of numerical modelling. The 3D numerical model is carried out via the Underworld framework that solves the Stokes flow equations using Finite Elements combined with a particle-in-cell approach, thus the discretization combines a standard Eulerian Finite Element mesh with Lagrangian particles. The model setup consists of two oceanic plates with a visco-plastic rheology subducting into the viscous upper mantle in opposite directions. In the present-day Alboran Basin region, the plate dips to the southeast with the trailing edge fixed to the Iberian margin, whereas in the present Algerian Basin region the plate dips to the northwest and the trailing edge is fixed to the African margin. To initiate subduction a small slab perturbation is initially imposed. In addition, we include a continental African plate segment west of the present Alboran Basin region, with different shear strength values. We study the influence of the lateral side plates on the trench curvature and the geodynamic consequences in terms of trench velocities, stress distribution, mantle flow, and plate deformation produced by the proximity between the opposite retreating slabs., This work is part of the projects ALPIMED (PIE-CSIC-201530E082) and MITE (CGL2014-59516-P). We also thank to the project AECT-2017-3-0008 of the Barcelona Supercomputing center (BSC-CNS).

Subduction trench curvature is generally attributed to the Earth's sphericity. Although, observed trench curvature in Nature are usually larger than those imposed by Earth radius. Other factors potentially influencing curvature are the mantle flow (produced by some other geodynamic process), internal heterogeneities in the subducting plate (e.g. variations in plate age and consequently in its thickness), the presence of crustal features (e.g. seamounts or plateaus), the orientation of the main plate structures (parallel/perpendicular to the trench) and the geometry of the upper plate. The role of a weak lithosphere on a lateral side perpendicular to the strike of the retreating subduction, e.g. continent/transfer zones, is unexplored. We study the influence of this boundary condition in a retreating subduction setting by varying its kinematic nature using analog modelling. A continental block is considered in one side of the plate, and the kinematic nature of the contact with the oceanic plate is varied considering: 1) fully attached, 2) half attached, and 3) completely free. To first order, lateral boundary perpendicular to the trench introduces an asymmetry in the trench curvature. The magnitude of this asymmetry is proportional to the resistance of the transfer zone. This kinematic resistance slows down the subduction of the oceanic plate near the contact and enhances the subduction in the free lateral side, thus affecting the retreat velocities along the trench. This work has implications for present and geologic past subduction zones where asymmetric trench and laterally varying retreat velocities have been observed/postulated. This is a SUBITOP (674899-SUBITOP-H2020-MSCA-ITN-2015) contribution., This is a SUBITOP (674899-SUBITOP-H2020-MSCA-ITN-2015) contribution.

In this study we present the results of numerical and analogue experiments of a double subduction system characterized by two adjacent slabs retreating in opposite directions. Such a tectonic scenario has been proposed to occur in several regions of the Earth, most recently in the Westernmost Mediterranean. The basic setup consists of two oceanic plates with a linear viscous rheology descending into the upper mantle. Both plates are fixed at their trailing edge to enforce roll-back behavior during subduction driven by a Rayleigh-Taylor instability. The two retreating plates interact with each other as a result of subduction-induced mantle counter-flow. Previous laboratory experiments, based on viscous syrup (representing the mantle) and silicone putty (representing the plates), show that the mantle flow induced by both plates is asymmetrical producing variations of rollback velocities and lateral separation between plates. Additionally, a high-resolution finite difference 3D numerical model (I3ELVIS code) is carried out with the identical material parameters and geometry as for the analogue model. The combination of both experiments allows us to numerically quantify the physical parameters that characterize the evolution of the system such as trench velocities, strain rates, and stresses. We also study how boundary conditions and scaling for analogue modelling may affect the numerical results., This work is part of the projects ALPIMED (PIE-CSIC-201530E082) and MITE (CGL2014-59516-P). We also thank to the project AECT-2017-3-0008 of the Barcelona Supercomputing center (BSC-CNS).