SM5.4 | Alpine-Mediterranean mountain belts and basins from mantle to surface studied by seismic large-scale passive experiments
Alpine-Mediterranean mountain belts and basins from mantle to surface studied by seismic large-scale passive experiments
Co-organized by GD9/TS6
Convener: Claudia Piromallo | Co-conveners: Petr Kolínský, Gergana Georgieva, Iva DasovićECSECS, Jordi Diaz
| Thu, 27 Apr, 10:45–12:30 (CEST)
Room 0.16
Posters on site
| Attendance Thu, 27 Apr, 14:00–15:45 (CEST)
Hall X2
Posters virtual
| Attendance Thu, 27 Apr, 14:00–15:45 (CEST)
Orals |
Thu, 10:45
Thu, 14:00
Thu, 14:00
We invite contributions that address the present and past structure and dynamics of the Alpine orogens and the back-arc basins of the Mediterranean area, which in the last decades has been the target of broadband large-scale passive experiments. The TopoIberia-Iberarray project, carried out in the 2000s in the Iberian Peninsula, is a successful example of the scientific progress that these experiments allow. More recently, the international AlpArray mission and related projects have generated a large amount of new data, not only seismic, to test the hypothesis that mantle circulation driving plates’ re-organization during collision has both immediate and long-lasting effects on the structure, motion, earthquake distribution and landscape evolution in mountain belts. Links between Earth’s surface and mantle have been forged by integrating 3D geophysical imaging of the entire crust-mantle system, with geologic observations and modelling to provide a look both backwards and forwards in time, the 4th dimension. This integrated 4D approach, initially focused on the Alps, has been expanded to the Pannonian-Carpathian region, with the ongoing PACASE experiment. A new initiative, AdriaArray, based on the deployment of the extensive AdriaArray Seismic Network, is underway to cover the Adria plate on both sides, including the Apennines and Dinarides-Hellenides, to shed light on plate-scale deformation and orogenic processes in this dynamic part of the Alpine-Mediterranean chain. This session provides an interdisciplinary platform for highlighting the newest results and open questions of the aforementioned projects, regions and themes.

Orals: Thu, 27 Apr | Room 0.16

Chairpersons: Claudia Piromallo, Petr Kolínský, Iva Dasović
On-site presentation
Stephen Beller, Najmieh Mohammadi, Vadim Monteiller, and Stéphane Operto

The Alps, which result from the convergence between the African and Eurasian plates, are an ideal natural laboratory to study the dynamics and evolution of continental orogens. This mountain range is indeed well documented both by geology and geophysics, which have notably allowed to highlight the different stages of continental subduction and collision during its formation. Nevertheless, large uncertainties remain about the 3D shape of structures and the internal composition of the Alps at crustal and upper mantle scales. This context motivated the European initiative AlpArray which deployed a dense array of more than 600 seismic sensors in the Alps and its periphery paving the way for the application of advanced seismic imaging techniques such as teleseismic waveform inversion (FWI). FWI is becoming a state-of-the-art method for lithospheric imaging as it allows the determination of various subsurface properties (seismic wavespeed, density, anisotropy or even attenuation) with high resolution and accuracy. In this study, we present the preliminary results of the LisAlps project which aimed at applying teleseismic FWI to the AlpArray  dataset to build isotropic and anisotropic high-resolution seismic models of the Alps from the surface down to the transition zone. Our preliminary application successfully built an isotropic (P and S seismic wave-speeds and density) model of the entire Alpine lithosphere from the assimilation of the first 60 s of the direct P waveforms of 18 teleseismic events within a period band ranging from 30 to 10 seconds. The resulting models recover large crustal structures of the Alpine range. In the crust, it recovers the surroundings sedimentary basins, crustal thickening in the internal part of the Alps as well as crustal thinning in the Ligurian sea and in the Ivrea zone. In the upper-mantle, where only the P wave-speed model is currently resolved, our model recovers large-scale mantle structures of the European and Apennines slabs.

How to cite: Beller, S., Mohammadi, N., Monteiller, V., and Operto, S.: Preliminary 3D isotropic full-waveform inversion model of the Alpine lithosphere from assimilation of AlpArray teleseismic body waves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6772,, 2023.

On-site presentation
Matteo Bagagli, Edi Kissling, Tobias Diehl, and Irene Molinari

The European Alps and its surrounding mountain belts (e.g., the northern Apennines, the northwestern Dinarides, and the western Carpathians) forms a tectonically complex system, referred as the “greater Alpine region” (GAR). Although being extensively  investigated, the evolving dynamic tectonic system and microplates relation are still under debate.

From 2016-2019 the AlpArray project, with its seismic network of ~700 broadband sensors, created an unprecedented chance to uniformly investigate the recorded seismicity in the GAR. After the successful compilation of the AlpArray research seismicity catalog (AARSC, Bagagli et al., 2022) we took a major leap to repick the seismicity reported by the European-Mediterranean Seismological Centre (EMSC) from May 2007 to December 2015. We use the same approach as for the AARSC to repick and consistently relocate 1397 events. Eventually, we consistently and homogeneously re-calculated the local magnitudes on the vertical component only (MLv). This allows a better data selection for the inversion stages, avoiding the magnitude scales mixing reported in bulletins. In addition to these two dataset, we also use the already published dataset for the latest GAR tomography spanning the time-period from January 1996 to May 2007 (Diehl et al., 2009). These three combined dataset have an average picking error observations of 0.2 seconds and provide an unique opportunity to perform a local earthquake tomography (LET) in the GAR.

We select 2343 MLv >=2.5 well-locatable events (azimuthal gap <180 degree, number of P-observations > 7) for the calculation of a new Minimum 1D model for the GAR. For the inversion procedure, we select 2285 events for a total of 84664 rays. The 99% of the rays are shorter than 350 km. We use SIMULPS software to derive the 3D P-wave velocity model using a model parametrization of 20x20x10 km cells in the well-resolved area. 

The preliminary velocity model correctly delineates the GAR major tectonic features, and due to the dense ray coverage it provides excellent resolution of the shallow crustal heterogeneities. This model will help the seismological community push forward the understanding of the GAR geodynamics.

How to cite: Bagagli, M., Kissling, E., Diehl, T., and Molinari, I.: A new 3D P-wave velocity model for the greater Alpine Region from 24 years of local earthquakes data., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9775,, 2023.

On-site presentation
Benedikt Braszus, Andreas Rietbrock, Christian Haberland, and Trond Ryberg

The increase in seismic data availability as well as the improvement of automated picking algorithms allows us to reassess the seismicity and velocity structure in many regions around the globe with higher accuracy. Using the seismic recordings from a total of more than 1100 stations of the AlpArray Seismic Network and other permanent and temporary stations within the area we work towards a comprehensive 3D P- and S-wave crustal velocity model for the European Alpine region using Local Earthquake Tomography. Phase arrival times of local seismicity are determined by the widely used deep neural network PhaseNet.
We present first a P- & S-wave minimum 1D model of the Greater Alpine region computed with the established linearized inversion algorithm VELEST and compare it to our new 1D model using a bayesian Markov chain Monte Carlo (McMC) algorithm exploring a broader model space. Pg and Pn phase arrivals in the epicentral distance ranges from 0-130km and 300-600km, respectively, are included while picks within the triplication zone from 130-300km are not considered due to difficult phase identification. Both models match within the error margin of the McMC result, while the discrepancy is largest in the lower crust where the resolution decreases due to the chosen epicentral distance ranges. 
With our minimum 1D model as starting model we compute a 3D P-wave model using the SIMULPS code. As the remaining residual distributions of the 1D and 3D model show, the removal of outliers in the pick catalog is more accurate when based on the 3D residuals due to insufficient incorporation of velocity variations along epicentral distance and backazimuth in the 1D model. The most prominent first order structures of the 3D model are in agreement with previous local studies of the area and the model already can be used to consistently improve crustal correction terms on an orogenic scale for teleseimic tomographies and thus sharpen the seismic image of the upper mantle. Furthermore, it will allow to the associate the phases Pg, Pmp & Pn to picked onset times in the crustal triplication zone more accurately. Due to their ray paths these picks are of special importance to the resolution in the lower crust and will contribute significantly to the final 3D P- and S-wave model. Absolute velocities along the Moho interface are higher than in previous studies and therefore in better accordance with values expected from petrology.  

How to cite: Braszus, B., Rietbrock, A., Haberland, C., and Ryberg, T.: AI based 1D and 3D P- and S-Wave Velocity Models for the Alpine Mountain Chain from Local Earthquake Data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12870,, 2023.

On-site presentation
Jaroslava Plomerova, Helena Zlebcikova, and AlpArray Working Group

First images of structure and dynamics of the Alpine orogeny came mostly from recordings of permanent observatories. Though density of permanent observatories has increased substantially since mid of the 20th century, yet it was not enough for detailed structural studies of the lithosphere-asthenosphere system in the complex Alpine-Mediterranean mountain belts. The tomographic images have changed especially during the last three decades, when several both small- and large-scale passive seismic experiments recorded huge amount of high-quality data at dense arrays, composed from both permanent and hundreds of temporarily installed stations. Thus the former monotonous eastward striking bend of the Alpine orogeny split into separated subductions with opposite polarity, one in the Western Alps and one in the Eastern Alps (Babuška et al., Tectonophysics 1990), later confirmed in more detailed tomography by Lippitsch et al. (2003), which included data from the TRANSALP experiment (TRANSALP Working Group, EOS 2001), the first research transect oriented on orogenic processes in the Eastern Alps. Data recorded during international AlpArray experiment, series of its complementary projects (e.g., EASI, SWATH-D, PACASE) as well as several other previous small-scale  experiments (e.g., ALPASS, BOHEMA, CIFALPS, CPB) allowed to unravel details of the Alpine structure and to search geodynamic models of the Alpine subductions. However, new questions arise with the new more precise images of the Alps. Following questions belong among them: 1) what is the origin of the E. Alpine subduction (Adriatic or European, or both); 2) if the E. Alpine slab is attached or detached, or, at which depth it resides; 3) how different methods, particularly crustal models incorporated into the body-wave tomography, disturb the real visualization of the E. Alpine slab. In this contribution we image the E. Alpine slab, evaluate effects of the crustal models on perturbations in the upper 100 km of the mantle and aim at answering the basic questions on the subduction beneath the Eastern Alps.

How to cite: Plomerova, J., Zlebcikova, H., and Working Group, A.: Where is the Eastern Alpine slab?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5577,, 2023.

On-site presentation
Somayeh Abdollahi, Piotr Sroda, Taghi Shirzad, and AniMaLS Working Group

During the last few years, the determination of the crust and upper mantle structures in southern Poland is the target of passive seismic experiments such as AniMaLS and PACASE. In this research, the area of Sudetes has been focused on that is located at the margin of the Bohemian Massif. This region represents the NE-most part of the Variscan internides between the Elbe Fault in SW and the Odra Fault in NE. The lithosphere of the region is a mosaic of several distinct units/terranes with complex tectonic history ranging from the upper Proterozoic to the Quaternary. 

To provide information about the crust and upper mantle structure beneath the Sudetes region, Ambient Noise Tomography Analysis has been used. As the input, continuous seismic data acquired during about 2 years (2017 to 2019)   have been used. The acquisition involved 41 broadband seismic stations — 23 temporary stations deployed in the area of Sudetes and Fore-Sudetic block in SW Poland, supplemented with the data from 12 permanent seismic stations, operating in this area in the Czech Republic, Germany, and Poland. Furthermore, data from 6 broadband seismic stations of the Alp Array Seismic Network have been used. 

Ambient seismic noise methods are now well-established and used in different period bands for different scales. To retrieve the surface wave dispersion curves from the vertical component of recorded noise for a given station pair, the cross-correlation in the frequency domain and stacking of noise records has been done. Then, the spectra from every combination of station pairs are cross-correlated by selecting the longest common time window available between the two stations and the average inter-station dispersion measurements with respect to the periods that have been retrieved. In the next step, the Multiple Filter Analysis technique was applied to analyze the waveforms and obtain the group velocity dispersion curves. In the final step, we are working on surface wave tomography and applying inversion for the shear (or compressional) velocities in the region. Based on the preliminary results, the depth resolution is between 5-50 km and the average shear velocity that is calculated so far is about 2.8 to 4.5 km/s at these depths. 

 Financial support 

This presentation is supported by the National Science Centre, Poland, according to the agreements UMO-2019/35/B/ST10/01628 and UMO-2016/23/B/ST10/03204. 


"The AniMaLS Working Group comprises: Monika Bociarska, Wojciech Czuba, Marek Grad, Tomasz Janik, Kuan-Yu Ke, Weronika Materkowska, Marcin Polkowski and Monika Wilde-Piórko." 


How to cite: Abdollahi, S., Sroda, P., Shirzad, T., and Group, A. W.: Ambient Noise Tomography Analysis in the Polish Sudetes: Preliminary results, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6250,, 2023.

On-site presentation
Rainer Kind, Stefan Schmid, Felix Schneider, Thomas Meier, Xiaohui Yuan, Ben Heit, and Christian Schiffer

For the understanding of the fate of the lithosphere when continents are colliding, it is necessary to image the structures of the lithosphere. In the case of the Alps, the structure of the Moho is very well known. This is, however, not yet the case for the lower boundary of the lithosphere, the lithosphere-asthenosphere boundary (LAB). We are using S-to-P converted seismic waves to study the structures of the Moho and the LAB beneath the greater Alpine Area with data from the Alparray project and the European networks of permanent seismic stations. Besides a new European Moho map, we present more detailed information about negative velocity gradients (NVG) below the Moho which may be interpreted as LAB. We found the European mantle lithosphere is deepening from about 50°N below the Alps to the Apennines and Dinarides along the entire east-west extension of the Alps. This area has also an east dipping component towards the Pannonian Basin and the Bohemian Massif. In the East and West of this area the European mantle lithosphere is dipping towards the North. We also discuss possible source locations of the volcanoes of the European Cenozoic Rift System in the light of our data.

How to cite: Kind, R., Schmid, S., Schneider, F., Meier, T., Yuan, X., Heit, B., and Schiffer, C.: Moho and sub-Moho structure in the larger Alpine area from S-to-P conversions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3927,, 2023.

On-site presentation
Dániel Kalmár, Laura Petrescu, Josip Stipčević, Attila Balázs, and István János Kovács and the the AlpArray Working Group

We perform the first, detailed S-to-P receiver function analysis to determine the depth of the lithospheric thickness in the Eastern Alps, Carpathians, and the Pannonian Basin. The Pannonian Basin hosts deep sedimentary depocentres superimposed on a complex basement structure and it is surrounded by mountain belts. The geophysical data on which investigated the lithospheric thickness was derived in the whole Pannonian Basin, are more than 20 years old. The determination and compilation of a new dataset is timely. This work is the first uniform and comprehensive S receiver function study of the Alpine-Carpathian-Pannonian system. We present our detailed workflow from the data download via quality controls to the calculations and interpretations of the S receiver functions in this study.

We use data from the temporary seismic networks, the permanent stations of the Hungarian National Seismological network, as well as the permanent seismological stations in neighboring countries for the time range between and 31.01.2022. Owing to the dense station coverage we can achieve so far unprecedented resolution, altogether 389 seismological stations are used in this study. This enables us to provide new, hitherto unknown information about the lithospheric thickness of the region. We apply two different quality control procedures for the downloaded waveforms and the calculated S receiver functions. S receiver functions are determined by the iterative time domain deconvolution approach.

We apply 1D and 2D migration of the S receiver function. We compare our result maps with map from previous geophysical investigation. We show migrated Common Conversion Point cross-sections beneath the Pannonian Basin and Carpathians, and the Eastern Alps–Pannonian Basin transition zone. Furthermore, we would like to provide new information about lithospheric thickness in the eastern part of the investigated region (e.g., Apuseni Mountains, Eastern-, Southern-Carpathians, Moesian Platform and Transylvanian Plateau).

Furthermore, we jointly interpret the S receiver function results with the seismic tomography calculations of the P and S wave

How to cite: Kalmár, D., Petrescu, L., Stipčević, J., Balázs, A., and Kovács, I. J. and the the AlpArray Working Group: S-to-P receiver function analysis in the Alpine-Carpathian-Pannonian system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3885,, 2023.

On-site presentation
Nicolas Bellahsen, Claudio Rosenberg, Ahmed Nouibat, Jean Baptiste Girault, Bastien Huet, Anne Paul, Loic Labrousse, Laurent Jolivet, Philippe Agard, Matthias Bernet, and Raphael pik

We provide new interpretations of the most recent geophysical models (Vs and Vp tomography mainly) coupled to geological surface information. We show that along-strike significant differences, but also first-order similarities in collision kinematics can be described from the Western to the Central Alps. Moreover, new, precise shortening estimates are obtained, giving some realistic convergence rates since 35 Ma.

In both the Western and Central Alps, after the subduction-collision transition (37-32 Ma), the orogen evolved to a doubly verging wedge with distributed shortening throughout the orogen during a first collision phase (~32-20 Ma) controlling the first mega-sequence of the molasse-type basin. From 20 Ma until recent times, the orogen was structured by localized west- or northwest-verging thrusts in the pro-side below the External Crystalline Massifs controlling the second mega-sequence of the molasse basin. This probably witnesses localization processes in the proximal European crust (i.e., below the Penninic Frontal Thrust) on a 10 Myr timescale. These structures (both distributed and localized ones) root in middle- to lower crustal low velocity (Vs) zones; the low seismic velocity being most probably controlled by fluid circulation, structural anisotropy, and/or metamorphic Alpine paragenesis (amphibolite facies). Balanced cross sections with realistic inherited Mesozoic structures allow locating the different paleogeographical domains at depth and then construction of the pre-collisional geometry.

In the Central Alps, the orogen forms a doubly verging wedge during both phases of collision with a strong amphibolite facies metamorphic imprint in the internal zone. There, the north-alpine foreland basin consists of a thick, large basin recording rather continuous sedimentation. At depth, the crustal root reaches a depth of around 50 km. Below the wedge, the subducting slab in the upper mantle is steep with no clear break-off, but possibly showing an area of attenuation.

In the Western Alps, doubly verging kinematics switch to west-verging kinematics between the two collisional phases and the overall collisional shortening is smaller than in the Central Alps; it is characterized by frontal accretion in the pro-side (while it corresponds to underplating/underthrusting in the Central Alps). As a consequence, the west alpine foreland basin is very segmented and composed of thin sub-basins. At depth, the crustal root is longer than in the Central Alps and underthrusted below the orogen down to at least 70 km. The slab in the upper mantle is moderately East-dipping with a probable break-off at around 120 km depth.

While similarities in terms of deformation localization in both parts of the orogen most likely reflect crustal rheology, the differences allow discussing the influence of both the inherited Mesozoic structure and the kinematics of Adria after the subduction phase.

How to cite: Bellahsen, N., Rosenberg, C., Nouibat, A., Girault, J. B., Huet, B., Paul, A., Labrousse, L., Jolivet, L., Agard, P., Bernet, M., and pik, R.: Kinematics of collisional processes in the Western and Central European Alps: Insights from a synthesis of geological data and new geophysical models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6047,, 2023.

On-site presentation
Anne Gaelle Bader, Philippe Calcagno, Nicolas Bellahsen, and Anne Paul

The French Geological Reference Platform (RGF) is a national programme for acquisition and management of geological data launched in the early 2010’s and coordinated by BRGM ( It involves the geosciences community to develop a new 3D knowledge of the underground to support innovative responses to a wide range of scientific first order questions as well as issues our society is facing. The RGF’s Alps and surrounding basins (Abp) worksite aims at a better understanding of the 3D structure of an emblematic mountain range and at addressing the impact of climate change and geological risk.

Within the RGF’s Abp, we proposed to build a 3D reference geomodel covering the area of the whole worksite ([41.5°N-48°N; 4°E-10°E]; ~350 000 km²) investigating the subsurface down to the Moho. This geomodel aims at federating the geoscientific community and intends to integrate existing data and information, e.g. geology, geophysics, relevant at that scale. It will be updated using the data acquired during the Abp worksite and serve to set up boundary information for local studies.

The geomodel is constructed in a collaborative approach where contributors discuss their data and knowledge and converge to a common interpretation of the investigated major geological boundaries that are the Moho (European lithosphere, Adriatic lithosphere, Ligurian backarc basin) and the boundaries of the subduction wedge.

We present here the state of progress of the geomodel based on the geological interpretive sections established at lithospheric scale by the RGF community (see Bellahsen at al., this session) and the integration of the available geophysical data and models (velocity models Vp and Vs, seismic reflection and refraction, gravimetry, etc.).

This work benefits from the French Geological Reference Platform - Alps and surrounding basins programme funding.

How to cite: Bader, A. G., Calcagno, P., Bellahsen, N., and Paul, A.: Towards a 3D crustal geomodel of the Western Alps in the French Geological Reference Platform (RGF), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11633,, 2023.

On-site presentation
Ivone Jimenez-Munt, Wentao Zhang, Montserrat Torné, Jaume Vergés, Estefanía Bravo-Gutierrez, Ana M Negredo, Eugenio Carminati, and Daniel Garcia-Castellanos

In this study we present a geophysical-geochemical integrated model of the thermochemical structure of the lithosphere and uppermost mantle of the Adria and Tisza microplates along two transects running from the Northern Apennines to the Pannonian Basin, and from the Southern Apennines to the Balkanides, respectively. The objectives are to image crustal thickness variations and characterize the different mantle domains. In addition, we evaluate the topographic response of opposed subductions and discuss their implications in the evolution of the region. Results show a more complex structure and slightly higher average crustal density of Adria compared to Tisza microplate. Below the Tyrrhenian Sea and Western Apennines, Moho is much shallower (< 25 km) than along the Eastern Apennines, where it can reach depths of 50-55 km. The LAB depth shows significant lateral variations, from the shallow LAB of the Tyrrhenian Sea and Western Apennines (< 80 km) to the thick LAB underneath the eastern Apennines and Adriatic Sea (150 and 125 km, respectively). Our results are consistent with the presence of two mantle wedges, resulting from the rollback of the Ligurian-Tethys and Vardar-NeoTethys oceanic slabs followed by continental mantle delamination of the eastern and western distal margins of Adria. These two opposed slabs beneath the Apennines and Dinarides are modelled as two thermal sublithospheric anomalies of -200°C. A Tecton garnet lherzolite (Tc_2 of Griffin et al., 2009) for the whole lithospheric mantle allows fitting geoid height and long-wavelength Bouguer anomalies. Most of the elevation along the profile is under thermal isostasy and departures can be explained by regional isostasy with an elastic thickness between 10 and 20 km.

This research has been funded by the GeoCAM Project (PGC2018-095154-B-I00) with the contribution of the China Scholarship Council.

How to cite: Jimenez-Munt, I., Zhang, W., Torné, M., Vergés, J., Bravo-Gutierrez, E., Negredo, A. M., Carminati, E., and Garcia-Castellanos, D.: Geophysical-petrological model for bidirectional mantle delamination of the Adria microplate beneath the Apennines and Dinarides orogenic systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14009,, 2023.

Posters on site: Thu, 27 Apr, 14:00–15:45 | Hall X2

Chairpersons: Claudia Piromallo, Gergana Georgieva, Jordi Diaz
Petr Kolínský, Thomas Meier, and the AdriaArray Seismology Group

With the advent of plate tectonics in the last century, our understanding of the geological evolution of the Earth system improved essentially. The internal deformation and evolution of tectonic plates remain however poorly understood. This holds in particular for the Central Mediterranean: The formerly much larger Adriatic plate is recently consumed in tectonically active belts spanning at its western margin from Sicily, over the Apennines to the Alps and at its eastern margin from the Hellenides, Dinarides towards the Alps. High seismicity along these belts indicates ongoing lithospheric deformation. It has been shown that data acquired by dense, regional networks like AlpArray provide crucial information on seismically active faults as well as on the structure and deformation of the lithosphere. The Adriatic Plate and in particular its eastern margin have however not been covered by a homogeneous seismic network yet.

Here we report on the status of AdriaArray – a seismic experiment to cover the Adriatic Plate and its actively deforming margins by a dense broad-band seismic network. Within the AdriaArray region, currently about 990 permanent broad-band stations are operated by more than 40 institutions. Data of 97% of these stations are currently available via EIDA. In addition to the existing stations, 414 temporary stations from 24 mobile pools are deployed in the region achieving a coverage with an average station distance of 50 – 55 km. The experiment is based on intense cooperation between local network operators, mobile pool operators, field teams, ORFEUS, and interested research groups. Altogether, more than 50 institutions are participating in the AdriaArray experiment. We will report on the time schedule, participating institutions, mobile station pools, maps of temporary station distribution with station coverage and main points of the agreed Memorandum of Collaboration. The AdriaArray experiment will lead to a significant improvement of our understanding of the geodynamic causes of plate deformation and associated geohazards.

How to cite: Kolínský, P., Meier, T., and Seismology Group, T. A.: AdriaArray Seismic Network – status in April 2023, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12284,, 2023.

Rens Hofman, Jörn Kummerow, and Simone Cesca and the AlpArray Working Group

We exploit a new template matching based catalogue to study the spatial
and temporal patterns of seismicity in the Eastern and Southern Alps. Data
from the AlpArray Swath-D network from late 2017 to late 2019 were used to
enhance the resolution of the seismic catalogues provided by local
agencies. The template matching method was implemented using our own
GPU-accelerated algorithm to deal with the large data volume. All events
are relocated using waveform-based picking methods.

Based on this result, we study statistical characteristics of the extended
seismicity catalogue, which now has a magnitude of completeness of Mc=0.6
and contains about 7,500 seismic events. We analyse the main spatial and
temporal features of seismicity revealed by this novel dataset. Finally,
we analyse specific event clusters that originated from the template
matching method, and seek to link event interconnectivity to geometrical
properties of the clusters.

How to cite: Hofman, R., Kummerow, J., and Cesca, S. and the AlpArray Working Group: Spatial and Temporal Patterns in Eastern-Alpine Seismicity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12921,, 2023.

Iva Dasović, Davorka Herak, Marijan Herak, Helena Latečki, Marin Sečanj, Bruno Tomljenović, Snježana Cvijić-Amulić, Marija Mustać Brčić, Tena Belinić Topić, and Josip Stipčević

A strong earthquake, ML = 6.0 (MW = 5.7), occurred on 22 April 2022 at 21:07 UTC with an epicentre near Berkovići in Bosnia and Herzegovina, with focal depth of about 20 km. The earthquake was felt throughout Bosnia and Herzegovina, Montenegro, Croatia (especially Dalmatia), but also in Slovenia, Italy (especially the western coast of the Adriatic), Serbia, Albania and North Macedonia. The maximum intensity of the earthquake was rated as VII–VIII EMS in Berkovići and Ljubinje. A young woman in Stolac lost her life from a rock slide caused by the earthquake. In the wider epicentral area the earthquake caused a number of large or small rock falls, many chimneys were damaged, tiles fell from the roofs, plaster fell off, and there were also large cracks in the walls.

By 31 October 2022, the DuFAULT project researchers located 6220 aftershocks (39 with ML≥ 3.0), with as many as 900 located in the first 12 h of the series. The strongest aftershock, ML = 4.9, occurred on 24 April 2022 at 4:27 UTC with focus at a depth of about 25 km and the epicentre also close to Berkovići. The vast majority of earthquakes have their foci relatively deep for this area, at depths between 15 and 28 km. Most of the epicentres form a compact group slightly elongated parallel to the NW-SE Dinaric strike, however two smaller groups northwest and southeast of the main group stand out with extension perpendicular to the Dinaric strike with somewhat shallower foci. The analysis of the focal mechanism and the hypocentral spatial distribution suggest that the mainshock resulted from the NE-SW directed compression and occurred on a reverse fault, on a moderately NE-dipping plane. Interestingly though, this series is also characterized by earthquakes released by a tension along the NE-SW striking and approximately 45° dipping normal faults, documented in the smaller north-western group.

We will present spatio-temporal analysis of seismicity, resulting focal plane solutions and seismotectonic interpretation.

How to cite: Dasović, I., Herak, D., Herak, M., Latečki, H., Sečanj, M., Tomljenović, B., Cvijić-Amulić, S., Mustać Brčić, M., Belinić Topić, T., and Stipčević, J.: The Berkovići (BA) 22 April 2022 earthquake sequence – seismological and seismotectonic analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13405,, 2023.

Caterina Montuori, Stephen Monna, Francesco Frugoni, Claudia Piromallo, Lev Vinnik, and AlpArray Working Group

We used the data from the dense, broadband AlpArray Seismic Network to derive a set of Receiver Function (RF) measurements on the Moho and Lithosphere-Asthenosphere Boundary (LAB) for a broad region encompassing the Western Alps and including the Ivrea Geophysical Body (IGB), a fragment of mantle emplaced in the lower continental crust. Our analysis fills an information gap since, in spite of numerous active and passive seismological investigations on the Alpine orogen, many of the observations focus on the Moho or the deeper part of the mantle, while reliable information on the LAB below the Alps is scarce. Moreover, our findings provide an additional contribution to resolving the debated topic of the existence of continuous or interrupted continental subduction below the Western Alps.

We derive seismic velocity profiles of the crust-uppermost mantle below each of the 50 analyzed stations down to about 250 km depth, through the joint inversion of P and S RFs. We constrain the lateral variations of the Moho and LAB topographies across the colliding plates, and quantify the errors related to our measurements. Our observations allow us to considerably expand the published data of the Moho depth and to add a unique set of new measurements of the LAB (Monna et al., 2022). 

Our results yield a comparable thickness (on average 90–100 km) of the Eurasia and Adria lithospheres, which are colliding below the IGB; Eurasia is not presently subducting below Adria with vertical continuity. These findings suggest that there is a gap between the superficial (continental) European lithosphere and the deep (oceanic) lithosphere, confirming the discontinuous structure imaged by some seismic tomography models.

the AlpArray Working Group: list on

Monna, S., Montuori, C., Frugoni, F., Piromallo, C., Vinnik, L., & AlpArray Working Group (2022). Moho and LAB across the Western Alps (Europe) from P and S receiver function analysis. Journal of Geophysical Research: Solid Earth, 127, e2022JB025141.

How to cite: Montuori, C., Monna, S., Frugoni, F., Piromallo, C., Vinnik, L., and Working Group, A.: Moho and LAB below the Western Alps from P and S Receiver Function analysis and joint inversion, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12370,, 2023.

Irene Bianchi, Irene Menichelli, and Claudio Chiarabba

Detailed 3D elastic crustal models are of fundamental relevance to many applications in Geosciences, from geodynamic modelling, to simulation of seismic wave propagation and seismic engineering. However, most of the recent models suffer from two main drawbacks: (1) they are often obtained from interpolation of local 1D models; and (2) they cannot be easily updated, without recomputing the entire model (which, as a corollary, implies the availability of the complete data-set of raw seismic data). The first drawback leads to mainly oversmoothed models on the horizontal scale, where vertical boundaries are not considered either in the 1D models and in the interpolated 3D model. The second disadvantage implies that current models are generally "static" and their updates require a research effort which is often not paying back in terms of outputs.

In this study, we build the framework for an evolutionary elastic model of the Central Apennines. The starting data are represented by a huge data-set of local 1D S-wave velocity models (originally obtained from Receiver Function inversion). We invert such data-set following a Bayesian fusion approach, where the full posterior probability distribution (PPD) of the1D models is exploited to build the 3D elastic model (in absence of the full PPD information, estimators like mean posterior and standard deviation can also be used). The 3D distribution of elastic properties (i.e. a model) is represented by a 3D Voronoi tassellation of the study volume, where the number of 3D Voronoi cells and their positions are unknown. A Markov chain Monte Carlo (McMC) algorithm is used to sample the family of Voronoi models which "fit" the data adequately (here the "data" are the PPD of the 1D models). 

Our results are shown on a regular 5x5x5 km grid down to 100 km depth, and they are consistent with previous models in terms of difference in crustal structure between the Tyrrhenian and Adriatic side of the Apennines. The model shows which of the features are coherent between adjacent stations, and which areas are better resolved. Point of strength over previous models is the possibility of identifying  sub-vertical boundaries, that in a complex region of subduction and neo-formed crust are more likely than a horizontally layered structure. More complementary or additional data (in the form, e.g. of tomographic models or 1D models from dispersion curves) can be easily added to this model, to update it, as new data become available. In fact, new "data" can be either added to the full data-set or can be included modifying the PPD of the 3D Voronoi cells.

How to cite: Bianchi, I., Menichelli, I., and Chiarabba, C.: Evolutionary 3D Vs crustal model for Central Apennines, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5849,, 2023.

Konstantinos Michailos and the AlpArray Receiver Function working group

The Alpine orogen is a unique geological formation with a highly variable crustal structure. Despite numerous active and passive seismic investigations in the past, constraints on the crustal structure across the whole Alpine domain are still limited. To improve on this, we use waveform data from four past and ongoing large-scale passive experiments in the broader Alpine region: namely the AlpArray Seismic Network (AASN), which also includes many permanent stations in its footprint, the Eastern Alpine Seismic Investigation (EASI), the China-Italy-France Alps seismic transect (CIFALPS-1) and the Pannonian-Carpathian-Alpine Seismic Experiment (PACASE). This results in a composite seismic network of more than 700 broadband seismic stations, providing unprecedented data coverage.  

We apply a systematic processing workflow to these data and calculate Receiver Functions (RF). After applying strict quality control we obtained 107,633 high-quality RF traces, on average of 122 per station. Next, we developed codes to perform time-to-depth migration in a newly implemented 3D spherical coordinate system using a reference P and S wave velocity model. Finally, we compiled a new detailed Moho map by manually picking the depth of the discontinuity. Our Moho depth estimates generally support the results of previous studies in the region and vary from ca. 20 to ca. 55 km depth with the maximum values observed beneath the Alpine orogen. The RF dataset along with the codes and new Moho map are all open-access. 

The high quality and homogeneously calculated RF dataset, along with the new, coherently derived Moho depth map of the Alpine region, can provide helpful information for interdisciplinary imaging and modeling studies investigating the geodynamics of the European Alps orogen and its forelands (e.g., joint inversions with other geophysical and geological datasets). 

How to cite: Michailos, K. and the AlpArray Receiver Function working group: Moho map and receiver functions database beneath the European Alps using data from recent large-scale passive experiments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13077,, 2023.

Andrés Olivar-Castaño, David Pedreira, Javier A. Pulgar, Marco Pilz, Alba Díaz-González, and Juan Manuel González-Cortina

The Basque-Cantabrian Zone (BCZ) is a large, inverted Mesozoic basin (the Basque-Cantabrian basin or BCB) forming part of the Pyrenean-Cantabrian mountain belt, in the north of Iberian Peninsula. The Mesozoic basin developed in one of the most subsident regions between the European plate and the Iberian sub-plate during the stage of crustal hyperextension linked to the rifting of the Central-North Atlantic and the opening of the Bay of Biscay. The high subsidence rate led to the accumulation of more than 15 km of sediments according to some estimates, and the significant crustal extension caused the exhumation of the mantle in the easternmost sector of the BCB. The Alpine orogeny caused the closure and inversion of the BCB and its incorporation to the Pyrenean-Cantabrian orogen. In this work, we studied the crustal structure of the BCZ resulting from this long and complex tectonic evolution using five years of continuous seismic recordings gathered by a local network of broadband stations, most of them deployed in the framework of projects SISCAN and MISTERIOS. A total of 66 locations were used (not all of them simultaneously), with an average spacing of ~30 km between stations. From this dataset, we extracted the multi-mode phase velocities of surface waves and the ellipticity of Rayleigh waves from cross-correlations of the seismic ambient noise. This allowed us to retrieve the shear-wave velocity structure of the crust, especially at shallow to intermediate depths. To better constrain the deeper crustal structure, we also extracted teleseismic P-wave receiver functions for all suitable events. Each dataset was carefully analyzed before performing a nonlinear, joint inversion using the simulated annealing technique. The result is a set of 1D shear-wave velocity models that represent a compromise between all three datasets. These 1D models were then used in a linear interpolation to build a 3D model of the BCZ. The main feature of the 3D model is a thickened crust of up to 50 km beneath the Cantabrian Mountains. A discontinuous, intracrustal level of high-velocities is identified in the northern part of the model, coherently with previous geological and geophysical observations, suggesting that the thick crustal root would be caused by the indentation of the Cantabrian Margin lower crust into the Iberian crust, as has been already proposed. This new 3D model fills a gap in the knowledge of the study area, whose seismic characterization was primarily based on active source studies, which often only provide estimates of the P-wave velocities along 2D profiles.

How to cite: Olivar-Castaño, A., Pedreira, D., Pulgar, J. A., Pilz, M., Díaz-González, A., and González-Cortina, J. M.: 3D Crustal structure of the Basque-Cantabrian Zone (N Spain) through a nonlinear joint inversion of surface wave phase velocities, teleseismic receiver functions and Rayleigh wave ellipticity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14741,, 2023.

Silvia Pondrelli, Judith M. Confal, and Paola Baccheschi

In a recent study, a large amount of splitting intensity measurements of the seismic anisotropy for the Central Mediterranean region has been made available, to retrieve an anisotropy tomography (see Baccheschi et al. and Confal et al. posters of session GD7.1). Here we focus on the images obtained for the Alpine region, that strongly benefit of AlpArray and Cifalps1 and 2 data. 
The 3-D distribution of seismic anisotropy, from 70 to 300 km of depth, has been compared with previous SKS shear wave splitting measurements and has been interpreted taking into account remnant and active pieces of slabs. Most of previously defined mantle flows are confirmed, as the asthenospheric toroidal flow around the tip of the slab beneath the Western Alps. Shallower anisotropy pattern show strong relation with main tectonic structures, from the Rhine Graben to the Western Alps arc and so on. However, the no uniqueness of available seismic velocity anomalies mapping keep some part of the interpretation open, as for instance the detectability of proper slab anisotropy. Out of the directional patterns, this splitting intensity tomography gives a map of anisotropy intensity and its variations with depth, with some strong heterogeneities corresponding to regions where previous seismic anisotropy studies described the presence of complex structure, as for the upper mantle beneath the Eastern Alps. All these new information, if integrated with the most recent studies for the Alpine region, may be a relevant support to innovative hypotheses on crust-to-mantle Alpine transition and structure.

How to cite: Pondrelli, S., Confal, J. M., and Baccheschi, P.: New Interpretations of the Deep Structure of the Alps based on 3D Anisotropy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7713,, 2023.

Najmieh Mohammadi, Stephen Beller, Vadim Monteiller, and Stephane Operto

The convergence between the African and European plates has created the magnificent Alpine chain with a very complex geological structure. This natural laboratory helps researchers to decipher the geotectonic processes imposed on the region. One useful way to understand better the prevailing geodynamics system is to interpret high-resolution crustal and upper-mantle models developed by full wavefield tomographic methods simultaneously. The high density of broadband stations deployed during the AlpArray project allows us to apply Full Waveform Inversion (FWI) on the teleseismic earthquakes recorded in the Alpine region. FWI minimizes the misfit between the entire recorded and simulated seismograms to reconstruct multiparameter models of the Earth’s interior with a resolution close to the wavelength. We used 203 teleseismic earthquakes with 6.8MW7.4 and 8depth630 km recorded by 1232 stations including permanent seismological broadband stations and AlpArray temporary seismic network. To model the propagation of the teleseismic wavefields through the target area, we used a hybrid technique that couples a global wavefield computed by AxiSEM in axisymmetric Earth from the source to the boundaries of the study area to regional wavefield propagating through the lithospheric domain computed by SPECFEM3DCartesian. This target-oriented wavefield injection method mitigates the computational cost of the wavefield simulation at the global scale, hence making high-frequency wavefield simulations in the lithospheric target possible (up to the 1Hz period). We use the AK135 velocity model as the initial model and iteratively inverted the band-pass filtered data at 10-30 s periods using the limited-memory BFGS optimization algorithm to obtain a 3D high-resolution elastic VP, VS, and density model for the crust and upper mantle of the entire Alpine chain. Our results show that the main documented structures of the Alps have been recovered well in the crust and upper mantle and confirm that a reliable geotechnical interpretation in the Alps depends on the consideration of the geodynamical process on Apennine and Dinaric simultaneously.

How to cite: Mohammadi, N., Beller, S., Monteiller, V., and Operto, S.: 3D high-resolution imaging of lithospheric VP, VS, and density structure in the Alps using full-waveform inversion of the teleseismic P waves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13742,, 2023.

Felix Borleanu, Laura Petrescu, Fabrizio Magrini, and Luca De Siena

The collisional area between the ALCAPA microplate and East European Craton across the Carpathian Orogen, is one of the most intriguing geological areas in Europe.  Here, a variety of tectonic processes are occurring simultaneously, including extensional basins, oceanic subduction, post-collisional volcanism, and active crustal deformation due to the push of the Adria plate or the pull of the actively detaching Vrancea slab, creating it a distinctive tectonic setting.

To explore the lithospheric structure of this collision region, broadband stations operating in the Carpatho-Pannonian area between 2006and 2022 were transformed into virtual sources by cross-correlating simultaneous noise recordings at pairs of stations in the frequency domain and stacking the cross-correlations to obtain one inter-station cross-correlogram per pair (Empirical Green functions). Rayleigh and Love phase velocities, as well as Rayleigh wave attenuation coefficients, were measured and mapped at six discrete periods (5, 10, 15, 25, and 30s) using the latest multiscale seismic imaging algorithms. We used a least-squares inversion approach based on ray theory with adaptive parameterization to map the lateral variations in surface-wave velocity, whereas the attenuation structures were revealed by mapping the frequency-dependent Rayleigh-wave attenuation coefficient.

Our results reveal a strong correlation between geology and tomographic images, suggesting a highly heterogeneous crust. An inverse correlation trend between Rayleigh wave phase velocity and attenuation maps was obtained for all period ranges, revealing a contrast between high attenuation features from the Pannonian Basin, including intra-Carpathian areas, and stable platform regions placed in front of the Carpathians. The shallow crust shear velocity model shows low velocities beneath Neogene and Paleozoic sedimentary basins and volcanic regions and high velocities under collisional fronts. In the middle to lower crust (25–30 km), high shear velocities beneath the Pannonian basin are in agreement with the previous findings.

How to cite: Borleanu, F., Petrescu, L., Magrini, F., and De Siena, L.: Shear wave velocity and attenuation tomography acquired from seismic ambient noise data analysis in a complex collisional area at the edge of the East European Craton, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15098,, 2023.

Sergi Ventosa, Martin Schimmel, Jordi Díaz, and Mario Ruiz

We present here a 3D shear-velocity regional model of the eastern Pyrenees centered at the Cerdanya Basin using seismic ambient noise to image structure of the Iberian and Eurasian uppermost crust. In the context of the SANIMS project, we deployed a network of 24 broadband seismic stations that complement existing permanent stations from the CA, ES and FR networks and previous temporal deployments from the OROGEN project, and aside, a high-density short-period seismic network focused on the study the Cerdanya Basin. For the regional study, we use the broadband dataset to compute symmetric cross-correlations of the seismic noise using the wavelet phase cross-correlation and the time-scale phase weighted stack, then estimate the phase and group velocity of Rayleigh waves between 1.5 – 7 s and 1.5 – 5 s, respectively. Afterwards, we build a 3D S-wave velocity model from path-average velocities in two steps: regionalization and pointwise depth inversion. In the regionalization step, we build velocity maps from the dispersion curves measured using the fast marching method on the forward problem and a hybrid l1 – l2 norm criterion on the inversion to enforce robustness to outliers. In the depth inversion step, we apply transdimensional inference to explore for S-wave velocity profiles with an unknown number of layers of constant velocity and the noise variance of the Rayleigh phase and group velocity maps using a least-square misfit function. The best models show a top low-velocity layer 2 – 3 km thick followed by distinct velocity profiles to the North and to the South, corresponding to the expected differences between the Iberian and Eurasian plates. To the South we observe two layers with a boundary at 6 – 7 km depth and velocities of about 3.2 and 3.5 km/s respectively, while to the North velocities are generally lower, increase much less with depth and there is no clear boundary.

How to cite: Ventosa, S., Schimmel, M., Díaz, J., and Ruiz, M.: Imaging the upper crust in the eastern Pyrenees with ambient seismic noise, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9451,, 2023.

Christian Schuler and Boris Kaus

The Alpine-Mediterranean region is area of interest for many studies seeking to better understand the geological evolution as well as the present-day mantle and lithosphere structure. However, despite numerous studies, the geological structure of the upper mantle and the geometry of the different subduction zones remain matter of debate.

Here, we use 3D geodynamic models to investigate the impact of the structure and material properties of the upper mantle and lithosphere on the motion of the Alpine-Mediterranean area. The geodynamic simulations are performed by the finite-difference code LaMEM (Kaus et al. (2016)) and a visco-plastic rheology is used to explore the dynamic behaviour of the upper mantle. In particular, we use the recently developed Julia interface to LaMEM to start simulations and read back the results which simplifies postprocessing and comparing the results to observational constraints.

Specifically, we compare the models with recently compiled GPS velocity data (Serpelloni at al. (2022)). As a result of the geological history in the Mediterranean the density and viscosity structure of the upper mantle is rather complex and influenced by various subduction zones, such that geometry, viscosity and density structures are primary parameters of interest in this study.

First results suggest that the Calabria subduction and the Hellenic subduction explain the fastest horizontal velocities in the Mediterranean whereas the horizontal motion in the Alpine area cannot arise from an active subduction zone but rather from large density and viscosity differences caused by the remnants of older subduction zones.


Kaus B J P, Popov A A, Baumann T S, Pusok A E, Bauville A, Fernandez N, and Collignon M (2016): Forward and inverse modelling of lithospheric deformation on geological timescales. Proceedings of NIC Symposium.

Serpelloni E, Cavaliere A, Martelli L, Pintori F, Anderlini L, Borghi A, Randazzo D, Bruni S, Devoti R, Perfetti P and Cacciaguerra S (2022): Surface Velocities and Strain-Rates in the Euro-Mediterranean Region From Massive GPS Data Processing. Front. Earth Sci. 10:907897. doi: 10.3389/feart.2022.907897

How to cite: Schuler, C. and Kaus, B.: Geodynamic inversion to explain the present-day plate motion in the Alpine-Mediterranean area, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7881,, 2023.

Posters virtual: Thu, 27 Apr, 14:00–15:45 | vHall GMPV/G/GD/SM

Chairpersons: Claudia Piromallo, Gergana Georgieva, Jordi Diaz
Joan Antoni Parera-Portell, Flor de Lis Mancilla, and José Morales

Thermal and compositional anomalies are known to drive changes in the thickness of the mantle transition zone (MTZ), as they modify the P-T conditions under which phase transitions occur. Typically, the phase changes defining the upper and lower boundaries of the MTZ take place at 410 km and 660 km respectively, thus yielding a standard MTZ thickness of 250 km. These phase transitions have opposite Clapeyron slopes, so while a cold temperature anomaly makes the 410 discontinuity shallower and the 660 deeper, a hot anomaly has the contrary effect. In this ongoing study we use P-wave receiver functions to map the MTZ discontinuities below southern Iberia and northwestern Africa and identify anomalous regions that can be linked to regional structures in the mantle. In this area, convergence of the African and Eurasian plates led to the subduction of the ancient Tethys oceanic lithosphere, from which a remnant slab is stalled below the Gibraltar arc, introducing thermal and chemical heterogeneities that alter the MTZ.

Roughly 33000 receiver functions were obtained from 501 seismic stations, from both permanent and temporary deployments, including four seismic profiles with high density of stations (interstation distances from 2 to 10 km). We constructed a grid of N-S and W-E sections with a spacing of 0.25x0.25 degrees by depth-migrating and projecting the receiver functions with a phase-weighted common conversion point stacking method. An algorithm for the automatic detection of the MTZ discontinuities was then used, and the results allowed us to obtain preliminary 2D and 3D maps containing the depth, width and number of peaks of the pulses attributed to the 410 and 660 discontinuities. Overall, the MTZ reaches its maximum thickness under the Alboran basin (290 km), but the region with anomalous thickness extends well into southeastern Iberia. This feature is attributable to a cold temperature anomaly and matches the position where tomographic studies locate the stalled Tethys slab. Two small areas in the Gulf of Cadiz also stand out for displaying a MTZ thickness of 290 km, coinciding with a region where the 410 discontinuity splits in two pulses. On the contrary, the MTZ is generally thinner than usual towards the south and west of the Alboran basin, especially in sections of the Rif and the Strait of Gibraltar where it can reach 205 km. Our results show, though, that while changes in the 410 discontinuity can be correlated with the tectonic configuration of the region and known anomalies in the mantle such as the Tethys slab, the 660 displays a much more unpredictable pattern.

How to cite: Parera-Portell, J. A., Mancilla, F. D. L., and Morales, J.: Mapping the mantle transition zone beneath the Ibero-Maghrebian region with P-wave receiver functions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11792,, 2023.