Seismology

The Slab Puzzle of the Alpine‐Mediterranean Region: Insights from a new, High‐Resolution, Shear‐Wave Velocity Model of the Upper Mantle

 

Model Name: MeRE2020
Type: 3-D shear wave tomographic model
Year: 2020
Depth coverage: Between 60 to 350 km depth
Area coordinates: Longitudes: -11°E - 46°E, latitudes: 29°N - 51°N)
   
DOI: https://doi.org/10.1029/2020GC008993
Publisher: Geochemistry, Geophysics, Geosystems

 

Description of the study:

High resolution shear wave velocity model of the Mediterranean upper mantle down to about 300 km (MeRE2020), constrained by a very large set of over 200,000 broadband (8‐350 s), inter‐station, Rayleigh‐wave, phase‐velocity curves. Phase‐velocity maps computed using these measurements were inverted for depth‐dependent, shear‐wave velocities using a new implementation of the stochastic particle‐swarm‐optimization algorithm (PSO). The resulting three‐dimensional (3‐D) model makes possible an inventory of slab segments across the Mediterranean. Fourteen slab segments of 200 ‐ 800 km length along‐strike are identified. We distinguish three categories of subducted slabs: attached slabs reaching down to the bottom of the model; shallow slabs of shorter length in down‐dip direction, terminating shallower than 300 km depth; and detached slab segments. The new high‐resolution tomography demonstrates the intricate relationships between slab fragmentation and the evolution of the relatively small and highly curved subduction zones and collisional orogens characteristic of the Mediterranean realm.

 

 

Shear wave velocity at 75 and 100km depth

Shear wave velocity at 200 and 250 km depth.

 

Data Set Description:

200.000 fundamental-mode, Rayleigh-wave, inter-station, earthquake-based phase-velocity dispersion curves. More than 3900 earthquakes recorded by around 4500 publically available seismic station provided by IRIS and WebDC in the time range 1990-2015 are used in this study. This is combined with restricted data from about 25 stations of the Egyptian National Seismological Network.

 

 

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Authors:

Amr El-Sharkawy:
Institute of Geosciences, Christian‐Albrechts‐Universität zu Kiel, Kiel, Germany
National Research Institute of Astronomy and Geophysics (NRIAG), Helwan, Cairo, Egypt

Thomas Meier, Christian Weidle and Daniel Köhn:
Institute of Geosciences, Christian‐Albrechts‐Universität zu Kiel, Kiel, Germany

Sergei Lebedev:
School of Cosmic Physics, Geophysics Section, Dublin Institute for Advanced Studies, Dublin, Ireland

Jan Behrmann:
GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany

Mona Hamada:
National Research Institute of Astronomy and Geophysics (NRIAG), Helwan, Cairo, Egypt

Luigia Cristiano:
Deutsches GeoForschungsZentrum (GFZ), Potsdam, Germany

Citation:

El-Sharkawy, A., Meier, T., Lebedev, S., Behrmann, J. H., Hamada, M., Cristiano, L., Weidle, C., Köhn, D. (2020). The slab puzzle of the Alpine-Mediterranean region: Insights from a new, high-resolution, shear wave velocity model of the upper mantle. Geochemistry, Geophysics, Geosystems, vol. 21, issue 8, e2020GC008993. https://doi.org/10.1029/2020GC008993