Acta Geophysica

, Volume 66, Issue 2, pp 153–165 | Cite as

Characterization of site conditions for selected seismic stations in eastern part of Romania

  • B. Grecu
  • B. Zaharia
  • M. Diaconescu
  • A. Bala
  • E. Nastase
  • E. Constantinescu
  • D. Tataru
Research Article - Solid Earth Sciences


Strong motion data are essential for seismic hazard assessment. To correctly understand and use this kind of data is necessary to have a good knowledge of local site conditions. Romania has one of the largest strong motion networks in Europe with 134 real-time stations. In this work, we aim to do a comprehensive site characterization for eight of these stations located in the eastern part of Romania. We make use of a various seismological dataset and we perform ambient noise and earthquake-based investigations to estimate the background noise level, the resonance frequencies and amplification of each site. We also derive the Vs30 parameter from the surface shear-wave velocity profiles obtained through the inversion of the Rayleigh waves recorded in active seismic measurements. Our analyses indicate similar results for seven stations: high noise levels for frequencies larger than 1 Hz, well defined fundamental resonance at low frequencies (0.15–0.29 Hz), moderate amplification levels (up to 4 units) for frequencies between 0.15 and 5–7 Hz and same soil class (type C) according to the estimated Vs30 and Eurocode 8. In contrast, the eighth station for which the soil class is evaluated of type B exhibits a very good noise level for a wide range of frequencies (0.01–20 Hz), a broader fundamental resonance at high frequencies (~ 8 Hz) and a flat amplification curve between 0.1 and 3–4 Hz.


Ambient seismic noise Resonance frequency Soil amplification Rayleigh waves Vs30 



This work was partly supported by a grant from the Romanian National Authority for Scientific Research and Innovation (ANCSI)-UEFISCDI, project number PN-II-RU-TE-2014-4-0701 and partly by a project carried out within Nucleu Program, supported by ANCSI, project number PN 16 35 01 01. The authors express their thanks to Viorel Pirvu who helped with the active seismic measurements performed at seismic stations.

Compliance with ethical standards

Conflict of interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.


  1. Balan SF, Ioane D, Cioflan C, Panea I, Apostol B, Malita Z, Chitea F, Anghelache MA (2014) Scenarios for local seismic effects of Tulcea (Romania) crustal earthquakes—preliminary approach of the seismic risk characterization for Tulcea city. In: Bostenaru D, Armas M, Goretti A (eds) Earthquake hazard impact and urban planning. Springer, Dordrecht, pp 85–103CrossRefGoogle Scholar
  2. Bard PY (1999) Microtremor measurements: a tool for site effects estimation. In: Irikura K, Kudo K, Okada H, Sasatani T (eds) The effects of surface geology on seismic motion. Balkema, Rotterdam, pp 1251–1279Google Scholar
  3. Dal Moro G (2008) VS and VP vertical profiling and poisson ratio estimation via joint inversion of Rayleigh waves and refraction travel times by means of bi-objective evolutionary algorithm. J Appl Geophys 66:15–24CrossRefGoogle Scholar
  4. Dal Moro G (2014) Surface wave analysis for near surface applications. Elsevier, Amsterdam, p 244Google Scholar
  5. Dal Moro G, Ferigo F (2011) Joint analysis of Rayleigh and love wave dispersion for near-surface studies: issues, criteria and improvements. J Appl Geophys 75:573–589CrossRefGoogle Scholar
  6. Dal Moro G, Pipan M, Gabrielli P (2007) Rayleigh wave dispersion curve inversion via genetic algorithms and marginal posterior probability density estimation. J Appl Geophys 61(1):39–55CrossRefGoogle Scholar
  7. Diaz J, Villasenor A, Morales J, Pazos A, Cordoba D, Pulgar J, Garcia-Lobon JL, Harnafi M, Carbonell R, Gallart J, TopoIberia Seismic Working Group (2010) Background noise characteristics at the IberArray Broadband Seismic Network. Bull Seismol Soc Am 100(2):618–628CrossRefGoogle Scholar
  8. Evangelidis CP, Melis NS (2012) Ambient noise levels in Greece as recorded at the Hellenic Unified Seismic Network. Bull Seismol Soc Am 102(6):2507–2517CrossRefGoogle Scholar
  9. Field EH, Jacob KH (1995) A comparison and test of various site-response estimation techniques, including three that are not reference-site dependent. Bull Seismol Soc Am 85(4):1127–1143Google Scholar
  10. Ghica DV, Grecu B, Popa M, Radulian M (2016) Identification of blasting sources in the Dobrogea seismogenic region, Romania using seismo-acoustic signals. Phys Chem Earth Parts A/B/C 95:125–134CrossRefGoogle Scholar
  11. Grecu B, Raileanu V, Bala A, Tataru D (2011) Estimation of site effects in the eastern part of Romania on the basis of H/V ratios of S and coda waves generated by Vrancea intermediate-depth earthquakes. Rom J Phys 56:563–577Google Scholar
  12. Grecu B, Neagoe C, Tataru D (2012) Seismic noise characteristics at the Romanian broadband seismic network. J Earthq Eng 16(5):644–661CrossRefGoogle Scholar
  13. Grecu B, Negoe C, Tataru D, Borleanu F, Zaharia B (2016) Analysis of seismic noise in the Romanian-Bulgarian cross-border region (submitted to Journal of Seismology)Google Scholar
  14. Grecu B, Neagoe C, Partheniu R, Nastase E, Zaharia B (2017) New seismic noise model for Romania, science and technologies in geology, exploration and mining. In: Proceedings of 17th International Multidisciplinary Scientific Geoconference, pp 285–292, Eds. STEF92 Technology Ltd (ISBN 976-619-7408-00-3)Google Scholar
  15. Ibs-von Seht M, Wohlenberg J (1999) Microtremor measurements used to map thickness of soft sediments. Bull Seis Soc Am 89(1):250–259Google Scholar
  16. Ionesi L (1989) Geologia Romaniei: unitati de platforma si orogenul Nord Dobrogean (translated title: The geology of Romania: platform units and the North-Dobrogean orogen). Thesis, Univ. Al. I. Cuza, Iasi, Romania. p 253 (in Romanian)Google Scholar
  17. Konno K, Ohmachi T (1998) Ground-motion characteristics estimated from spectral ratio between horizontal and vertical components. Bull Seis Soc Am. 88(1):228–241Google Scholar
  18. Lermo J, Chávez-García FJ (1993) Site effect evaluation using spectral ratios with only one station. Bull Seismol Soc Am 83(5):1574–1594Google Scholar
  19. Matenco L, Bertotti G, Cloetingh S, Dinu C (2003) Subsidence analysis and tectonic evolution of the external Carpathian-Moesian Platform region during Neogene times. Sed Geol 156:71–94CrossRefGoogle Scholar
  20. McNamara DE, Buland RP (2004) Ambient noise levels in the continental United States. Bull Seis Soc Am 94:1517–1527CrossRefGoogle Scholar
  21. Nakamura Y (1989) A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface. QR Railw Tech Res Inst 30:25–33Google Scholar
  22. Oncescu MC, Marza V, Rizescu M, Popa M (1999) The Romanian earthquakes catalogue between 984 and 1997. In: Wenzel F, Lungu D (eds) Vrancea earthquakes: tectonics, hazard and risk mitigation. Kluwer Academic Publishers, Berlin, pp 43–47CrossRefGoogle Scholar
  23. Peterson J (1993) Observation and modeling of seismic background noise, U.S. Geol. Surv. Tech. Rept. 93–322, pp 1–95Google Scholar
  24. Philips WS, Aki K (1986) Site amplification of coda waves from local earthquakes in central California. Bull Seism Soc Am 76:627–648Google Scholar
  25. Popa M, Oros E, Dinu C, Radulian M, Borleanu F, Rogozea M, Munteanu I, Neagoe C (2016) The 2013 earthquake swarm in the galati area: first results for a seismotectonic interpretation. In: Vacareanu R, Ionescu C (eds) The 1940 Vrancea Earthquake. issues, insights and lessons learnt. Springer International Publishing, Switzerland. Google Scholar
  26. Radulian M, Mandrescu N, Panza GF, Popescu E, Utale A (2000) Characterization of seismogenic zones of Romania. In: Panza G, Radulian M, Trifu C (eds) Seismic hazard of the Circum-Pannonian Region. Birkhäuser, Basel, pp 57–77CrossRefGoogle Scholar
  27. Raileanu V (2006) Annual report for the Contract no: 31 N/23.01.2006, Project—Advanced research of the disaster management of the strong Romanian earthquakes, Director of the project dr. Raileanu V., NIEPGoogle Scholar
  28. Sandulescu M (ed) (1984) Geotectonica Romaniei (translated title: Geotectonics of Romania). Tehnica, Bucharest, p 335 (in Romanian) Google Scholar
  29. Site Effects Assessment using Ambient Excitations (SESAME) European project (2005) Deliverable D23.12—Guidelines for the implementation of the H/V spectral ratio technique on ambient vibrations: measurements, processing and interpretation.
  30. Stutzmann E, Schimmel M, Patau G, Maggi A (2009) Global climate imprint on seismic noise. Geochem Geophys Geosyst. Google Scholar

Copyright information

© Institute of Geophysics, Polish Academy of Sciences & Polish Academy of Sciences 2018

Authors and Affiliations

  • B. Grecu
    • 1
  • B. Zaharia
    • 1
  • M. Diaconescu
    • 1
  • A. Bala
    • 1
  • E. Nastase
    • 1
  • E. Constantinescu
    • 1
  • D. Tataru
    • 1
  1. 1.National Institute for Earth PhysicsMăgureleRomania

Personalised recommendations