Regionally adjusted ground motion model: Case study of the ML6.2 (Mw6.4) Petrinja (Croatia) 2020 earthquake

• Published in: Studia geophysica et geodaetica 2022-10, Vol.66 (3-4), p.162-186
• Main Authors: Uglešić, Jakov Stanislav, Skendrović, Filip, Lončar, Iva, Markušić, Snježana, Stanko, Davor
• Format: Article
• Language: English
• Subjects: Atmospheric Sciences; Earth and Environmental Science; Earth Sciences; Earthquakes; Frequency ranges; Geological hazards; Geophysics/Geodesy; Ground motion; Instruments; Modelling; Movement; Random vibration; Seismic activity; Seismic hazard; Seismicity; Structural Geology; Vibration
• ISSN: 0039-3169; 1573-1626
• DOI: 10.1007/s11200-022-0914-6

In the wake of recent 2020 M L ≥ 5.5 earthquakes in Croatia, Zagreb M L 5.5 and Petrinja M L 6.2, the insufficient instrumental network as well as the lack of regional ground motion prediction equation (GMPE) were identified as the drawbacks of our engineering community. The former is related to the quality definition of active seismicity (most of the instruments are installed in the southern part of Croatia with fewer installed around Zagreb in the northwestern part of Croatia), and the latter is related to the proper number of strong motion recordings. In Croatia, there is a sparse database of ground motion recordings for moderate earthquakes which makes a well-designed ground motion selecting procedure hardly achievable. Following this, strong motion BSHAP database for empirical estimation of the response spectrum based on Fourier amplitude spectrum and the ground motion duration using Random Vibration Theory approach adjusted to source, propagation, and local site conditions was used. Regionally adjusted ground motion model estimations for the M L 6.2 Petrinja 2020 earthquake scenario are comparable with the previously published GMPEs models for this part of Europe and for the Western part of North America. However, model-to-model variability and uncertainties in local GMPE exceeded those of global GMPEs and are influenced by statistically less stable and more limited datasets. Model is applicable for magnitudes up to M w 6.5 and Joyner-Boore distances up to 200 km with usable frequency range between 0.4 and 33 Hz. The presented model is a step forward toward performing hybrid-empirical seismic hazard studies in areas with sparse ground motions such as the region of Croatia.