26 Jul 2023
 | 26 Jul 2023
Status: a revised version of this preprint is currently under review for the journal NHESS.

Seismogenic depth and seismic coupling estimation in the transition zone between Alps, Dinarides and Pannonian Basin for the new Slovenian seismic hazard model

Polona Zupančič, Barbara Šket Motnikar, Michele M. C. Carafa, Petra Jamšek Rupnik, Mladen Živčić, Vanja Kastelic, Gregor Rajh, Martina Čarman, Jure Atanackov, and Andrej Gosar

Abstract. The seismogenic depth and seismic coupling are important inputs into seismic hazard estimates. Although the importance of seismic coupling is often overlooked, it significantly impacts seismic hazard results. We present an estimation of upper and lower seismogenic depth and hypocentral depth and seismic coupling in the transition zone between the Alps, Dinarides and Pannonian Basin, characterized by complex deformation pattern, highly variable crustal thickness, and moderate seismic hazard, supporting the development of the 2021 seismic hazard model of Slovenia. We estimated the lower seismogenic depth using seismological and geological data and compared them. The seismological estimate was based on two regional earthquake catalogues prepared for this study. In the area source model, estimates of lower seismogenic depth from seismological data are deeper or equal to the ones derived from geological data, except in one case. In the fault source model, we analyzed each fault individually and chose seismological lower depth estimates in 12 among 89 faults as more representative. The seismogenic thickness for each individual fault source was determined for seismic coupling determination. The seismic coupling was assessed by two approaches, i.e. we chose the most trusted value from the literature, and the value determined for each fault individually by using the approach based on the updated regional fault and earthquake datasets. The final estimate of seismic coupling ranges from 0.77 to 0.38. We compared the tectonic moment rate based on long-term slip rate using different values of seismic coupling with the seismic moment rate obtained from the earthquake catalogue. The analysis is done for the whole area, as well as for the individual area zones. The analysis of N-S components of estimated slip for the largest faults in the area of west Slovenia shows that the regional geologic and geodetic shortening rates are comparable. The total activity rate of three global seismic source models is compared, which gives up to a 10 % difference. Our results contribute to a better understanding of the seismic activity in the region and the approach for seismic coupling estimation can be applied in other similar regions.

Polona Zupančič et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on nhess-2023-127', Anonymous Referee #1, 23 Aug 2023
    • AC1: 'Reply on RC1', Polona Zupančič, 25 Sep 2023
  • RC2: 'Comment on nhess-2023-127', Anonymous Referee #2, 02 Sep 2023
    • AC2: 'Reply on RC2', Polona Zupančič, 25 Sep 2023

Polona Zupančič et al.

Polona Zupančič et al.


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Short summary
We considered two parameters that affect seismic hazard assessment in Slovenia. The first parameter we determined is the thickness of the lithosphere's section where earthquakes are generated. The second parameter is the activity of each fault, which is expressed by its average displacement per year (slip rate). Since the slip rate can be either seismic or aseismic, we estimated both components. This analysis was based on geological and seismological data and was validated through comparisons.