Strong ground motion records of the Zagreb earthquake of 22 March 2020

Prevolnik, Snježan; Markušić, Snježana; Ivančić, Ines

doi:10.5592/co/1crocee.2021.248

Cited by 4 publications

(12 citation statements)

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“…4 (case 2) and Fig. 7b are similar to those predicted by the USGS shake map (https://earthquake.usgs.gov/data/shakemap/) and strong motions records (Prevolnik et al, 2021). Except of direct comparison of EQL modelled PGA surf (amplification factor at zero period) with empirical strong motions records (QUHS and QARH), it is interesting to compare 2D model of variation of PGA surf (Fig.…”

Section: Sitesupporting

confidence: 70%

“…1-10) following both input rock motion scenarios with detailed site param eters (V S30 , fundamental frequency, estimated bedrock depth). Prevolnik et al (2021) presented strong motion records of the M L 5.5 Zagreb earthquake record ed on two stations located close to the epicentres (approx. 10 km distant): station QARH to be 0.20 g and station QUHS to be 0.22 g with presumable classification of ground type C by Eurocode 8 (EN1998-1).…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, Anba zhagan et al ( 2013) also observed that the AF in site response analysis can be different when the input ground motions are applied at depths shallower than 30 m. Also, presence of high plasticity clays can substantially amplify ground shaking (Dobry and Vučetić, 1987). Prevolnik et al (2021) presented strong motion records of the M L 5.5 Zagreb earthquake recorded on two stations located close to the epicentres (10 km): sta Figure 8. Response spectra at surface for earthquake scenario "case 2" with Eurocode 8 (Type 1) spectra for 95 (0.12 g), 225 (0.18 g), and 475 (0.25 g) yrp (Herak et al, 2011) compared to the me dian response spectra (thick black line) from 1D EQL site response analysis for site profiles No.…”

Section: Sitementioning

confidence: 99%

“…At the time of Markušić et al (2020) publication, strong ground motion re cords of the M L 5.5 Zagreb earthquake were not publicly available, so direct com parison and validation with accelerometric measurements were not possible. Prevolnik et al (2021) presented strong motion records of the M L 5.5 Zagreb earthquake recorded on two stations located close to the epicentres (about 10 km): station QARH to be 0.20 g and station QUHS to be 0.22 g with presumable clas sification of ground type C by Eurocode 8 (EN1998-1). However, both ground motion amplification studies (Lokmer et al, 2002;Markušić et al, 2020) were made without publicly available reports on detailed geotechnical and geophysical local site condition investigations or microzonation studies mostly determined by geological or inferred from topographic data.…”

Section: Introductionmentioning

confidence: 97%

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Semi-empirical estimation of the Zagreb ML 5.5 earthquake (2020) ground motion amplification by 1D equivalent linear site response analysis

Uglešić

Markušić

Padovan³

et al. 2022

Geofizika (Online)

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The 22 March 2020 Zagreb ML 5.5 earthquake ground shaking resulted in damage to buildings and infrastructure. The most affected buildings were older and cultural heritage buildings (built before 1963) in the old city centre with significant damage extent in the epicentral zone (southeastern foothills of Medvednica Mt.). This study presents site response analysis on the realistic site profiles from the epicentre towards the accelerometric stations QUHS and QARH and comparison with strong motion data recorded during the Zagreb 2020 earthquake. Semi-empirical estimation of the ground motion amplification (i.e., peak ground acceleration at surface) showed that modelled and recorded values are comparable. Moreover, we present 2D model of peak ground acceleration at surface (PGAsurf ) variation for the superimposed site profile from the epicentre towards two accelerometric stations. Ground motion amplification for the Zagreb ML 5.5 earthquake scenario showed that PGAsurf is larger by a factor of 2 than the bedrock value (approx. 0.35 g in the epicentre and 0.20 g on the 12 km distant accelerometric station). This study is a contribution to better understanding of the Zagreb ML 5.5 earthquake effects and significance of local site effects in the damage extent, something that combined with older and heritage buildings resulted in high economic consequences. Therefore, it is important that site-specific ground motion simulation and seismic microzonation of the Zagreb continues with installation of an accelerometric array. This is very important for earthquake retrofitting and resilience of the low, mid- and high-rise buildings with particular care of cultural and historical buildings as well for the further urban planning.

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Section: Sitesupporting

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Section: Sitementioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Semi-empirical estimation of the Zagreb ML 5.5 earthquake (2020) ground motion amplification by 1D equivalent linear site response analysis

Uglešić

Markušić

Padovan³

et al. 2022

Geofizika (Online)

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“…If site amplification [14] is considered, we can estimate that resulting peak ground acceleration was between 0.03 and 0.11 g. Again, if we consider a distance of about 40-50 km from the location of the Zagreb 2020 earthquake to the Trakošćan site, estimated peak ground acceleration using attenuation relation for the rock is about 0.03 g [22]. With accounted site amplification [14], ground shaking can be assumed between 0.06 and 0.10 g. We compared these assumed values with recorded ground motions-accelerations for the Zagreb 2020 event recorded on stations 10 km distant from the epicenter were about 0.20 g on alluvial sediment sites [23], whereas six accelerometric stations in Zagreb recorded the Petrinja 2020 event on different local sites in a range of 0.04 g up to 0.25 g (see analysis of accelerogram for Petrinja earthquake, [24]).…”

Section: Ambient Vibration Measurements: Pre-and Post-earthquakesmentioning

confidence: 99%

Preliminary Observations on Historical Castle Trakošćan (Croatia) Performance under Recent ML ≥ 5.5 Earthquakes

et al. 2021

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Trakošćan Castle, built on a rocky peak in the late 13th century, is a cultural heritage site protected as a historical entity by the Republic of Croatia. The Castle is constructed as a highly irregular masonry structure with timber or shallow masonry arches, vaults or dome floors. It was substantially renewed, upgraded and partially retrofitted from the 16th century until the year 2000. The M5.5 (VIII EMS) and M6.2 (VIII-IX EMS) earthquakes, which struck the city of Zagreb on 22 March 2020 and the Pokupsko-Petrinja area on 29 December 2020, strongly shook the Castle’s structure. Earthquake damage was observed and assessed by visual inspection accompanied by ambient vibration measurements. The slight cracks that appeared on masonry arches were found to be critically positioned, and can likely lead to the arches’ collapse if their spreading is not prevented. Ambient vibration measurements, which were compared to pre-earthquake ones, revealed the decrease in the fundamental frequencies of the Castle’s central tower unit and the second floor, thus possibly indicating the loss of structural stiffness as a consequence of the earthquake damage.

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The Mw5.4 Zagreb (Croatia) earthquake of March 22, 2020: impacts and response

Atalić

Uroš

Novak

et al. 2021

Bull Earthquake Eng

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This paper highlights the principal features of the Mw5.4 Zagreb earthquake. Located within the city limits at a depth of 10 km, the earthquake generated a peak ground acceleration of more than 0.2 g and a maximum spectral acceleration of about 0.6 g at 0.1 s in the historic downtown area. The situation was particularly challenging since the event occurred amid a partial Covid-19 lockdown at temperatures close to 0 °C, emphasizing the extensive and complex vulnerability of the local communities and individuals. 27 people were reported severely injured, one of which later died. The surprisingly high economic costs, needed to achieve a full reconstruction of damaged buildings and infrastructure in the affected area, are currently evaluated at more than 10B euros. Description of the organization of the emergency response in the first days and the observed damage to buildings is given with typical examples. The focus is on the performance of older masonry residential and cultural heritage buildings in the historic downtown, their inspection and evaluation of damage to structural and non-structural components. This information provides the basis for understanding of the negative impacts and clarifies the overall context identifying the enablers and barriers to the still ongoing recovery process. It also helps to increase the awareness of the seismic vulnerability of European cities with similar construction practices.

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Strong ground motion records of the Zagreb earthquake of 22 March 2020

Cited by 4 publications

References 0 publications

Semi-empirical estimation of the Zagreb ML 5.5 earthquake (2020) ground motion amplification by 1D equivalent linear site response analysis

Semi-empirical estimation of the Zagreb ML 5.5 earthquake (2020) ground motion amplification by 1D equivalent linear site response analysis

Preliminary Observations on Historical Castle Trakošćan (Croatia) Performance under Recent ML ≥ 5.5 Earthquakes

The Mw5.4 Zagreb (Croatia) earthquake of March 22, 2020: impacts and response

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