A newly compiled high-quality ground-shaking dataset of 207 intermediate-depth earthquakes recorded in the Vrancea region of the south-eastern Carpathian mountains in Romania was used to develop region-specific empirical predictive equations for various intensity measures: peak ground acceleration, peak ground velocity, and 5%-damped pseudo-spectral acceleration up to 10 s. Besides common predictor variables (e.g. moment magnitude, depth, hypocentral distance, and site conditions), additional distance scaling parameters were added to describe the specific attenuation pattern observed at the stations located not only on the back and fore but also along the Carpathian arc. In this model, we introduce a proxy measure for the site as the fundamental frequency of resonance to characterize the site response at each recording seismic station beside the soil classes. To additionally reduce the site-to-site variability, a non-ergodic methodology was considered, resulting in a lower standard deviation of about 25%. Statistical evaluation of the newly proposed ground-motion models indicates robust performance compared to regional observations. The model shows significant improvements in describing the spatial variability (at different spectral ordinates), particularly for the fore-arc area of the Carpathians where a deep sedimentary basin is located. Furthermore, the model presented herein improves estimates of ground shaking at longer spectral ordinates (>1 s) in agreement with the observations. The proposed ground-motion models are valid for hypocentral distances less than 500 km, depths over 70 km and within the moment magnitude range of 4.0–7.4.
AbrahamsonNGregorNAddoK (2016) BC Hydro ground motion prediction equations for subduction earthquakes. Earthquake Spectra32(1): 23–44.
2.
AkaikeH (1974) A new look at the statistical model identification. IEEE Transactions on Automatic Control19(6): 716–723.
3.
AkkarSBommerJJ (2006) Influence of long-period filter cut-off on elastic spectral displacements. Earthquake Engineering and Structural Dynamics35: 1145–1165.
4.
Al AtikLAbrahamsonNBommerJJScherbaumFCottonFKuehnN (2010) The variability of ground-motion prediction models and its components. Seismological Research Letters81(5): 794–801.
5.
AllenTIWaldDJ (2009) On the use of high-resolution topographic data as a proxy for seismic site conditions (Vs30). Bulletin of the Seismological Society of America 99(2A):935–943.
6.
AndersonJGBruneJN (1999) Probabilistic seismic hazard analysis without the ergodic assumption. Seismological Research Letters70(1): 19–28.
7.
AschK (2003) The 1:5 million international geological map of Europe and adjacent areas: Development and implementation of a GIS-enabled concept. Geologisches Jahrbuch SA 3, Stuttgart: E. Schweizerbartsche Verlagsbuchhandlung.
8.
AtkinsonGMBooreDM (2003) Empirical ground-motion relations for subduction-zone earthquakes and their application to Cascadia and other regions. Bulletin of the Seismological Society of America93(4): 1703–1729.
9.
BaltayASAbrahamsLSHanksTC (2020) When source and path components trade-off in ground-motion prediction equations. Seismological Research Letters91(4): 2259–2267.
10.
BaltayASHanksTCAbrahamsonN (2017) Uncertainty, variability, and earthquake physics in ground-motion prediction equations. Bulletin of the Seismological Society of America107(4): 1754–1772.
11.
BatesDMaechlerMBolkerBWalkerS (2015) Fitting linear mixed-effects models using lme4. Journal of Statistical Software67(1): 1–48.
12.
BokelmannGRodlerFA (2014) Nature of the Vrancea seismic zone (Eastern Carpathians): New constraints from dispersion of first-arriving P-waves. Earth and Planetary Science Letters390: 59–68.
13.
BommerJJAbrahamsonNA (2006) Why do modern probabilistic seismic-hazard analyses often lead to increased hazard estimates?Bulletin of the Seismological Society of America96(6): 1967–1977.
14.
BooreDMStewartJPSeyhanEAtkinsonGM (2014) NGA-West2 equations for predicting PGA, PGV, and 5% damped PSA for shallow crustal earthquakes. Earthquake Spectra30(3): 1057–1085.
15.
BooreDM (2010) Orientation-independent, nongeometric-mean measures of seismic intensity from two horizontal components of motion. Bulletin of the Seismological Society of America100(4): 1830–1835.
16.
CadetHBardPYDuvalAMBertrandE (2012) Site effect assessment using KiK-net data: Part 2—Site amplification prediction equation based on f0 and Vsz. Bulletin of Earthquake Engineering10(2): 451–489.
17.
CastellaroSMulargiaFRossiPL (2008) VS30: Proxy for seismic amplification?Seismological Research Letters79(4): 540–543.
18.
CauzziCFaccioliE (2018) Anatomy of sigma of a global predictive model for ground motions and response spectra. Bulletin of Earthquake Engineering16(5): 1887–1905.
19.
ChambersJM (1992) Linear models. In: ChambersJMHastieTJ (eds) Statistical Models in S. Chapter 4, pp. 95–144. Wadsworth & Brooks/Cole Advanced Books & Software, USA.
20.
ChaoSHLinCMKuoCHHuangJYWenKLChenYH (2020) Implementing horizontal-to-vertical Fourier spectral ratios and spatial correlation in a ground-motion prediction equation to predict site effects. Earthquake Spectra37: 827–856.
21.
ChiouBSJYoungsRR (2014) Update of the Chiou and Youngs NGA model for the average horizontal component of peak ground motion and response spectra. Earthquake Spectra30(3): 1117–1153.
22.
CioflanCOManeaEFApostolBF (2021) Insights from Neo: Deterministic seismic hazard analyses in Romania. In: PanzaGKossobokovVGLaorEDe VivoB (eds) Earthquakes and Sustainable Infrastructure: Neodeterministic (NDSHA) Approach Guarantees Prevention Rather than Cure. Chapter 20, pp. 415–429, Amsterdam: Elsevier.
23.
CioflanCOMarmureanuAMarmureanuG (2009) Nonlinearity in seismic site effects evaluation. Romanian Journal of Physics54(9-10): 951–964.
24.
ComanAManeaEFCioflanCORadulianM (2020) Interpreting the fundamental frequency of resonance for Transylvanian Basin. Romanian Journal of Physics65: 809.
25.
Comité Européen de Normalisation (CEN) (2004) Eurocode 8, design of structures for earthquake resistance—Part 1: General rules, seismic actions and rules for buildings. European Standard NF EN 1998-1. Brussels: CEN.
26.
ConstantinAPPanteaAStoicaR (2011) Vrancea (Romania) subcrustal earthquakes: historical sources and macroseismic intensity assessment. Romanian Journal of Physics, 56: 813826.
27.
CraiuMMărmureanuACraiuAIonescuC (2015) Real time earthquake location performance of Romanian seismic network (RONET) for Vrancea intermediate depth earthquakes, as the first step in EEWS. International Multidisciplinary Scientific GeoConference3: 925–932.
28.
DanciuLHiemerSNandanSWeatherillGLammersSRovidaAMaesanoFE (2019). Status, milestones and next activities on the development of the 2020 European seismic hazard model (ESHM20). Geophysical Research Abstracts21: 1–1.
29.
DanciuLŞeşetyanKDemirciogluMGülenLZareMBasiliREliasAAdamiaSTsereteliNYalçınHUtkucuM (2018.) The 2014 earthquake model of the Middle East: Seismogenic sources. Bulletin of Earthquake Engineering16(8): 3465–3496.
30.
DouglasJ (2020) Ground motion prediction equations 1964 -2020. Available at: http://www.gmpe.org.uk (accessed October 12, 2020).
31.
DouglasJEdwardsB (2016) Recent and future developments in earthquake ground motion estimation. Earth-Science Reviews160: 203–219.
32.
EnescuBDEnescuD (2005) Isoline maps of ground motion acceleration caused by the Vrancea (Romania) earthquake of May 30, 1990: Comparison with the macroseismic intensity map. Romanian Reports in Physics57(1): 141–150.
33.
FähDKindFGiardiniD (2003) Inversion of local S-wave velocity structures from average H/V ratios, and their use for the estimation of site-effects. Journal of Seismology7(4): 449–467.
34.
HassaniBAtkinsonGM (2016) Applicability of the site fundamental frequency as a VS 30 proxy for central and eastern North America. Bulletin of the Seismological Society of America106(2): 653–664.
35.
HassaniBAtkinsonGM (2018) Site-effects model for central and eastern North America based on peak frequency and average shear-wave velocity. Bulletin of the Seismological Society of America108(1): 338–350.
36.
Ismail-ZadehAMatencoLRadulianMCloetinghSPanzaG (2012) Geodynamic and intermediate-depth seismicity in Vrancea (the south-eastern Carpathians): Current state-of-the-art. Tectonophysics530–531: 50–79.
37.
Ismail-ZadehASchubertGTsepelevIKorotkiiA (2008) Thermal evolution and geometry of the descending lithosphere beneath the SE-Carpathians: An insight from the past. Earth and Planetary Science Letters273(1–2): 68–79.
38.
Ismail-ZadehASolovievASokolovVVorobievaIMüllerBSchillingF (2018) Quantitative modeling of the lithosphere dynamics, earthquakes and seismic hazard. Tectonophysics746: 624–647.
39.
IvanM (2007) Attenuation of P and pP waves in Vrancea area —Romania. Journal of Seismology11(1): 73–85.
40.
KothaSRWeatherillGBindiDCottonF (2020) A regionally-adaptable ground-motion model for shallow crustal earthquakes in Europe. Bulletin of Earthquake Engineering18: 4091–4125.
41.
KronrodTRadulianMPanzaGPopaMPaskalevaIRadovanovichSPekevskiL (2013) Integrated transnational macroseismic data set for the strongest earthquakes of Vrancea (Romania). Tectonophysics590: 1–23.
42.
KtenidouOJRoumeliotiZAbrahamsonNCottonFPitilakasKHollenderF (2018) Understanding single-station ground-motion variability and uncertainty (sigma): Lessons learnt from EUROSEISTEST. Bulletin of Earthquake Engineering16(6): 2311–2336.
43.
KwakDYStewartJPMandokhailSJParkD (2017) Supplementing VS30 with H/V spectral ratios for predicting site effects. Bulletin of the Seismological Society of America107(5): 2028–2042.
44.
LinPSLeeCT (2008) Ground-motion attenuation relationships for subduction-zone earthquakes in northeastern Taiwan. Bulletin of the Seismological Society of America98(1): 220–240.
45.
ManeaEFCioflanCOComanAMichelCPoggiVFähD (2020) Estimating geophysical bedrock depth using single station analysis and geophysical data in the extra-Carpathian area of Romania. Pure and Applied Geophysics177: 4829–4844.
46.
ManeaEFComanACioflanCO (2021) Evaluation of the predominant frequency of resonance of sedimentary layers using 2014 5.7 ML Vrancea crustal event records. Romanian Reports in Physics73(3).
47.
ManeaEFMichelCHobigerMFähDCioflanCORadulianM (2017) Analysis of the seismic wavefield in the Moesian Platform (Bucharest area) for hazard assessment purposes. Geophysical Journal International210(3): 1609–1622.
48.
ManeaEFMichelCPoggiVFähDRadulianMBalanFS (2016) Improving the shear wave velocity structure beneath Bucharest (Romania) using ambient vibrations. Geophysical Supplements to the Monthly Notices of the Royal Astronomical Society207(2): 848–861.
49.
ManeaEFPredoiuACioflanCDiaconescuM (2019) Interpretation of resonance fundamental frequency for Moldavian and Scythian platforms. Romanian Reports in Physics71: 709.
50.
MarmureanuAIonescuCGrecuBToma-DanilaDTiganescuANeagoeCIlieşI (2021) From national to transnational seismic monitoring products and services in the Republic of Bulgaria, Republic of Moldova, Romania, and Ukraine. Seismological Society of America92(3): 1685–1703.
51.
MarmureanuGCioflanCOMarmureanuA (2008) New approach on seismic hazard isoseismal map for Romania. Romanian Reports in Physics60(4): 1123–1135.
52.
MarmureanuGManeaEFCioflanCOMarmureanuAToma-DanilaD (2017) Spectral response features used in last IAEA stress test to NPP Cernavoda (ROMANIA) by considering strong nonlinear behaviour of site soils. Romanian Journal of Physics62: 822.
53.
MarmureanuGMarmureanuAManeaEFToma-DanilaDVladM (2016) Can we still use classic seismic hazard analysis for strong and deep Vrancea earthquakes?Romanian Reports in Physics61(3–4): 728–738.
54.
NakamuraY (1989) A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface. Quarterly Report of Railway Technical Research Institute30: 25–30.
55.
OlteanuPVacareanuR (2020) Ground motion model for spectral displacement of intermediate-depth earthquakes generated by Vrancea seismic source. Geosciences10(8): 282.
56.
OthAWenzelFRadulianM (2007) Source parameters of intermediate-depth Vrancea (Romania) earthquakes from empirical Green’s functions modeling. Tectonophysics438(1–4): 33–56.
57.
PaganiMMonelliDWeatherillGDanciuLCrowleyHSilvaVSimionatoM (2014) OpenQuake engine: An open hazard (and risk) software for the global earthquake model. Seismological Research Letters85(3): 692–702.
58.
PavelFVacareanuR (2016) Scaling of ground motions from Vrancea (Romania) earthquakes. Earthquakes and Structures11(3): 505–516.
59.
PavelFVacareanuRDouglasJRadulianMCioflanCBarbatA (2016) An updated probabilistic seismic hazard assessment for Romania and comparison with the approach and outcomes of the SHARE project. Pure and Applied Geophysics173(6): 1881–1905.
60.
PinheiroJCBatesDM (1995) Approximations to the log-likelihood function in the nonlinear mixed-effects model. Journal of Computational and Graphical Statistics4(1): 12–35.
61.
PinheiroJCBatesDM (2000) Linear mixed-effects models: Basic concepts and examples. In: PinheiroJCBatesDM (eds) Mixed-Effects Models in S and S-Plus. New York: Springer, pp. 3–56.
62.
PinheiroJDBatesSDebRoyD, Sarkar and R Core Team (2018) nlme: Linear and Nonlinear Mixed Effects Models (R Package version 3.1-137). Available at: https://CRAN.R-project.org/package=nlme (accessed December 12, 2019).
63.
PitilakisKRigaEAnastasiadisAFotopoulouSKarafagkaS (2019) Towards the revision of EC8: Proposal for an alternative site classification scheme and associated intensity dependent spectral amplification factors. Soil Dynamics and Earthquake Engineering126: 105137.
64.
PitilakisKRigaEAnastasiadisA (2013) New code site classification, amplification factors and normalized response spectra based on a worldwide ground-motion database. Bulletin of Earthquake Engineering11(4): 925–966.
65.
PoggiVFähDBurjanekJGiardiniD (2012) The use of Rayleigh-wave ellipticity for site-specific hazard assessment and microzonation: Application to the city of Lucerne, Switzerland. Geophysical Journal International188(3): 1154–1172.
66.
RadulianMPanzaGFPopaMGrecuB (2006) Seismic wave attenuation for Vrancea events revisited. Journal of Earthquake Engineering10(03): 411–427.
67.
Rodriguez-MarekACottonFAbrahamsonNAAkkarSAl AtikLEdwardsBDawoodHM (2013) A model for single-station standard deviation using data from various tectonic regions. Bulletin of the Seismological Society of America103(6): 3149–3163.
68.
Rodriguez-MarekARathjeEMBommerJJScherbaumFStaffordPJ (2014) Application of single-station sigma and site-response characterization in a probabilistic seismic-hazard analysis for a new nuclear site. Bulletin of the Seismological Society of America104(4): 1601–1619.
69.
Rodriguez-MarekABommerJJYoungsRRCrespoMJStaffordPJBahrampouriM (2020) Capturing epistemic uncertainty in site response. Earthquake Spectra37: 921–936.
70.
SørensenMBStromeyerDGrünthalG (2010) A macroseismic intensity prediction equation for intermediate depth earthquakes in the Vrancea region, Romania. Soil Dynamics and Earthquake Engineering30(11): 1268–1278.
71.
SchwarzG (1978) Estimating the dimension of a model. Annals of Statistics6: 461–464.
72.
SkarlatoudisAAPapazachosCBMargarisBNVentouziCKalogerasI and EGELADOS Group (2013) Ground-motion prediction equations of intermediate-depth earthquakes in the Hellenic Arc, southern Aegean subduction area. Bulletin of the Seismological Society of America103(3): 1952–1968.
73.
SokolovVBonjerKPWenzelFGrecuBRadulianM (2008) Ground-motion prediction equations for the intermediate depth Vrancea (Romania) earthquakes. Bulletin of Earthquake Engineering6(3): 367–388.
74.
StrasserFOAbrahamsonNABommerJJ (2009) Sigma: Issues, insights, and challenges. Seismological Research Letters80(1): 40–56.
75.
VacareanuRPavelFAldeaA (2013) On the selection of GMPEs for Vrancea subcrustal seismic source. Bulletin of Earthquake Engineering11(6): 1867–1884.
76.
VacareanuRRadulianMIancoviciMPavelFNeaguC (2015) Fore—arc and back—arc ground motion prediction model for Vrancea intermediate depth seismic source. Journal of Earthquake Engineering19(3): 535–562.
77.
VillaniMAbrahamsonNA (2015) Repeatable site and path effects on the ground-motion sigma based on empirical data from southern California and simulated waveforms from the CyberShake platform. Bulletin of the Seismological Society of America105(5): 2681–2695.
78.
WaldDWaldLWordenBGoltzJ (2003) ShakeMap: A tool for earthquake response U.S. Geological Survey Fact Sheet 087-03.
79.
WeatherillGKothaSRCottonFBindiDDanciuL. (2020) D25.4: Updated GMPE Logic Tree and rock/soil parameterization for ESHM18. SERA deliverable 254.
80.
WeatherillGADanciuL (2018) Regional variation of spectral parameters for seismic design from broadband probabilistic seismic hazard analysis. Earthquake Engineering and Structural Dynamics47(12): 2447–2467.
81.
WoessnerJDanciuLGiardiniDCrowleyHCottonFGrünthalGValensiseGArvidssonRBasiliRDemirciogluMBHiemerSMelettiCMussonRWRovidaANSesetyanKStucchiM and The SHARE Consortium (2015) The 2013 European seismic hazard model: Key components and results. Bulletin of Earthquake Engineering13(12): 3553–3596.
82.
YenierEAtkinsonGM (2015) Regionally adjustable generic ground-motion prediction equation based on equivalent point-source simulations: Application to central and eastern North America. Bulletin of the Seismological Society of America105: 1989–2009.
83.
ZhaoJXZhangJAsanoAOhnoYOouchiTTakahashiTOgawaHIrikuraKThioHKSomervillePFukushimaYFukushimaY (2006) Attenuation relations of strong ground motion in Japan using site classification based on predominant period. Bulletin of the Seismological Society of America96: 898–913.
84.
ZhuCPilzMCottonF (2020) Which is a better proxy, site period or depth to bedrock, in modelling linear site response in addition to the average shear-wave velocity?Bulletin of Earthquake Engineering18(3): 797–820.
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