Preprints
https://doi.org/10.5194/se-2020-192
https://doi.org/10.5194/se-2020-192

  25 Nov 2020

25 Nov 2020

Review status: a revised version of this preprint was accepted for the journal SE and is expected to appear here in due course.

Relocation of earthquakes in the Southern and Eastern Alps (Austria, Italy) recorded by the dense, temporary SWATH–D network using a Markov chain Monte Carlo inversion

Azam Jozi Najafabadi1,2, Christian Haberland1, Trond Ryberg1, Vincent Verwater3, Eline Le Breton3, Mark R. Handy3, Michael Weber1, and the AlpArray working group Azam Jozi Najafabadi et al.
  • 1GFZ German Research Centre for Geosciences, Potsdam, Germany
  • 2Institute of Geosciences, Potsdam University, Potsdam, Germany
  • 3Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
  • For further information regarding the team, please visit the link which appears at the end of the paper.

Abstract. Local earthquakes with magnitudes in the range of 1–4.2 (ML) in the Southern and Eastern Alps (2017–2018) registered by the dense, temporary SWATH-D network and the AlpArray network reveal seismicity in the upper crust (0–20 km). The seismicity is characterized by pronounced clusters along the Alpine frontal thrust, e.g., Friuli-Venetia (FV) region, in the Giudicarie-Lessini (GL) and Schio-Vicenza domains, as well as in the Austroalpine Nappes and the Inntal area. Some seismicity also occurs along the Periadriatic Fault. The general pattern of seismicity reflects head-on convergence of the Adriatic Indenter with the Alpine orogenic crust. The deeper seismicity in the FV and GL regions indicate southward propagation of the Southern Alpine deformation front (blind thrusts). The first arrival-times of P- and S-waves of earthquakes are determined by an automatic workflow and then visually/manually checked and corrected. We applied a Markov chain Monte Carlo inversion method to achieve precise hypocenter locations of the 344 local earthquakes. This approach simultaneously calculates hypocenters, 1-D velocity model, and station-corrections without prior assumptions such as initial velocity models and earthquake locations. A further advantage of the method is the derivation of the model parameter uncertainties and noise levels of the data. The accuracy of the localization procedure is checked by inverting a synthetic travel-time dataset from a complex 3-D velocity model and using the real stations and earthquakes geometry. The location accuracy is further investigated by the relocation of quarry blasts. The average uncertainties of the locations of the earthquakes are below 500 m in the epicenter and ∼1.7 km in depth when using the average VP and VP/VS models and the station-corrections from the simultaneous inversion.

Azam Jozi Najafabadi et al.

 
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Status: closed
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Azam Jozi Najafabadi et al.

Data sets

The Swath-D Seismic Network in Italy and Austria Heit, Benjamin, Weber, Michael, Tilmann, Frederik, Haberland, Christian, Jia, Yan, and Pesaresi, Damiano https://doi.org/10.14470/MF7562601148

Azam Jozi Najafabadi et al.

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Short summary
The achieved high precision hypocenter locations of 344 earthquakes (with magnitudes in the range of 1–4.2 ML) have average uncertainties of ~500 m in epicenter and ~1.7 km in depth. The general pattern of seismicity in the Southern and Eastern Alps reflects head-on convergence of the Adriatic Indenter with the Alpine orogenic crust. The relatively deeper seismicity clusters in the eastern Southern Alps and Giudicarie Belt indicate southward propagation of the Southern Alpine deformation front.