Crustal and upper mantle 3D Vs structure of the Pannonian Region from joint earthquake and ambient noise Rayleigh wave tomography

Máté Timkó,Amr El-Sharkawy,Sergei Lebedev,Lars Wiesenberg,Thomas Meier,Zoltán Wéber,László Fodor

doi:10.5194/egusphere-egu22-7892

Máté Timkó, Amr El-Sharkawy + Show 5 more

https://doi.org/10.5194/egusphere-egu22-7892

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&lt;p&gt;The Pannonian basin is a continental back-arc basin in Central Europe, surrounded by the Alpine, Carpathian, and Dinaric mountain ranges. To better understand this area's tectonic affinity and evolution, a high-resolution model of the crust, the mantle lithosphere, and the asthenosphere is essential. The region's crustal structures are well documented, e.g., classical active seismic, receiver functions, and ambient noise surface wave studies, but consistent imaging of the entire lithosphere remains a challenge. Here we present a new high-resolution 3D shear wave velocity model of the crust and upper mantle of the broader Pannonian region using joint tomographic inversion of ambient noise and earthquake data.&lt;/p&gt;&lt;p&gt;For this purpose, we collected continuous waveform data from more than 1280 seismic stations for ambient noise cross-correlation measurements from a region centered to the Pannonian Basin and encompassing the rimming orogenic chains. This dataset embraces all the permanent and temporary stations operated in the time period from 2005 to 2018. We calculated Rayleigh wave ambient noise phase velocity dispersion curves using the phase of the noise cross-correlation functions of the vertical components in the period range from 5 to 80 s. Then we combined this dataset with existing measurements from earthquake data in the period range of 8-300 s.&lt;/p&gt;&lt;p&gt;At lower periods (&lt; 50 s) and shorter interstation distances, there is a well-documented systematic discrepancy between the dispersion measurements collected by the two methods. The phase-velocity curves measured by the noise-based method are slower on average than the dispersion curves extracted by the earthquake-based method. A correction term is defined by comparing phase velocity curves from both data sets for the same station pairs. Phase velocity maps are then calculated from 5 s to 250 s periods using ambient noise and earthquake measurements.&lt;/p&gt;&lt;p&gt;Local dispersion curves extracted along each grid node of the 2D phase velocity maps are inverted for depth velocity models using a newly implemented Particle Swarm Optimization (PSO) algorithm to obtain the 3D distribution of the shear-wave velocities. The shear wave velocity structure reveals pronounced variations of the lithospheric thickness and physical properties related to deep tectonic mechanisms operated in the region.&lt;/p&gt;

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