Impact of distribution of seismic ambient noise sources on surface wave characteristics

نوع مقاله : مقاله تحقیقی‌ (پژوهشی‌)

نویسندگان

1 Ph.D student, Department of Seismology, Institute of Geophysics, University of Tehran, Tehran, Iran

2 Assistant Professor, Department of Seismology, Institute of Geophysics, University of Tehran, Tehran, Iran

چکیده

The seismic ambient noise observation is widely used in site characterization studies to obtain the subsurface velocity structure because of the simplicity and low cost. Different single and array methods have been introduced in this field to study seismic ambient noise characteristics. In this paper, we investigated the effects of distributions of the seismic ambient noise sources on surface wave properties. In this regard, two datasets are simulated regarding omnidirectional and non-omnidirectional distributions of sources. In the former, it is assumed that the waves travel through the array from all even azimuths and for the latter, an arc shape distribution is considered. To process the data, the RTBF (Rayleigh three component beamforming) array signal processing technique is applied to retrieve Rayleigh and Love phase velocity dispersion curves and Rayleigh wave ellipticity. Furthermore, two well-known single station methods HVTFA (horizontal to vertical time frequency analysis) and RayDec (random decrement technique) are implemented to extract the ellipticity curves. For all the applied methods, impacts of the two considered distributions of sources are investigated. Then, the results are compared to theoretical curves which are computed from a specific earth model used to produce synthetic noise data. Moreover, a data recorded in Ramsar (north of Iran), as a typical case of non-omnidirectional distribution of noise sources, selected to justify our assertion in processing synthetic noise data. Benefitting the mentioned array and single station methods, the characteristics of surface waves are studied and the shear wave velocity profile is estimated by joint inversion of retrieved dispersion and ellipticity curves.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Impact of distribution of seismic ambient noise sources on surface wave characteristics

نویسندگان [English]

  • Naimeh Sadat Moghadasi 1
  • Elham Shabani 2
1 Ph.D student, Department of Seismology, Institute of Geophysics, University of Tehran, Tehran, Iran
2 Assistant Professor, Department of Seismology, Institute of Geophysics, University of Tehran
چکیده [English]

The seismic ambient noise observation is widely used in site characterization studies to obtain the subsurface velocity structure because of the simplicity and low cost. Different single and array methods have been introduced in this field to study seismic ambient noise characteristics. In this paper, we investigated the effects of distributions of the seismic ambient noise sources on surface wave properties. In this regard, two datasets are simulated regarding omnidirectional and non-omnidirectional distributions of sources. In the former, it is assumed that the waves travel through the array from all even azimuths and for the latter, an arc shape distribution is considered. To process the data, the RTBF (Rayleigh three component beamforming) array signal processing technique is applied to retrieve Rayleigh and Love phase velocity dispersion curves and Rayleigh wave ellipticity. Furthermore, two well-known single station methods HVTFA (horizontal to vertical time frequency analysis) and RayDec (random decrement technique) are implemented to extract the ellipticity curves. For all the applied methods, impacts of the two considered distributions of sources are investigated. Then, the results are compared to theoretical curves which are computed from a specific earth model used to produce synthetic noise data. Moreover, a data recorded in Ramsar (north of Iran), as a typical case of non-omnidirectional distribution of noise sources, selected to justify our assertion in processing synthetic noise data. Benefitting the mentioned array and single station methods, the characteristics of surface waves are studied and the shear wave velocity profile is estimated by joint inversion of retrieved dispersion and ellipticity curves.

کلیدواژه‌ها [English]

  • Seismic noise
  • Distribution of noise sources
  • ellipticity curve
  • Dispersion curve
  • Shear wave velocity profile
  • Site effects
Aki, K., 1957, Space and time spectra of stationary stochastic waves, with special reference to microtremors: Bulletin of the Earthquake Research Institute, 35, 415-456.
Asmussen, J. C., 1997, Modal Analysis Based on the Random Decrement Technique: Application to Civil Engineering Structures: PhD thesis, University of Aalborg, Denmark.
Bonnefoy-Claudet, S., Cotton, F., and Bard, P. Y., 2006, The nature of noise wavefield and its applications for site effects studies, A literature review: Earth-Science Review, 79, 205-227, doi 10.1016/j.earscirev.2006.07.004.
Capon, J., 1969, High-resolution frequency-wavenumber spectrum analysis: Proceeding of IEEE, 57, 1408-1418, doi  10.1109/PROC.1969.7278.
Fäh, D., Kind, F., and Giardini, D., 2001, A theoretical investigation of average H/V ratios: Geophys. J. Int., 145, 535-549.
Fäh, D., Kind, F., and Giardini, D., 2003, Inversion of local S-wave velocity structures from average H/V ratios, and their use for the estimation of site-effects: Journal of Seismology, 7, 449-467, doi 10.1023/B:JOSE.0000005712.86058.42.
Fäh, D., Wathelet, M., Kristekova, M., Havenith, H., Endrun, B., Stamm, G., Poggi, V., Burjanek, J., and Cornou, C., 2009, Using Ellipticity Information for Site Characterisation: NERIES deliverable JRA4D4, Final Report, http://www.neries-jra4.geopsy.org.
Foti, S., Parolai, S., Albarello, D., and Picozzi, M., 2011, Application of Surface-Wave Methods for Seismic Site Characterization: Surveys Geophysics, 32, 777–825. doi:10.1007/s10712-011-9134-2.
Hisada, Y., 1994, An efficient method for computing Green’s functions for a layered half-space with sources and receivers at depths: Bull. Seism. Soc. Am., 84(5), 1456-1472.
Hisada, Y., 1995, An efficient method for computing Green’s functions for a layered half-space with sources and receivers at close depths (Part 2): Bull Seism. Soc. Am., 85(4), 1080-1093.
Hobiger, M., Bard, P. Y., Cornou, C., and Le Bihan, N., 2009, Single station determination of Rayleigh wave ellipticity by using the random decrement technique (RayDec): Geophys. Res. Lett., 36, doi 10.1029/2009GL038863.
Hobiger, M., 2011, Polarization of surface waves: characterization, inversion and application to seismic hazard assessment: PhD thesis, University of Joseph Fourier, Grenoble, France.
Köhler, A., Ohrnberger, M., Scherbaum, F., Wathelet, M., and Cornou, C., 2007, Assessing the reliability of the modified three-component spatial autocorrelation technique: Geophys. J. Int., 168, 779-796.
Lacoss, R. T., Kelly, E. J., and Toksöz, M. N., 1969, Estimation of seismic noise structure using arrays: Geophysics, 34, 21-38, doi 10.1190/1.1439995.
Maranò, S., Reller, C., Loeliger, H. A., and Fäh, D., 2012, Seismic waves estimation and wavefield decomposition: Application to ambient vibrations: Geophys. J. Int., 191, 175-188, doi:10.1111/j.1365-246X.2012.05593.x.
Moczo, P., and Kristek, J., 2002, FD Code to generate noise synthetics: SESAME Rep. D02.09, IGSAS, Bratislava, http://SESAME-FP5.obs.ujf-grenoble.fr.
Nakamura, Y., 1989, A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface: Quarterly Report of RTRI, 30(1), 25-33.
Nogoshi, M., and Igarashi, T., 1971, On the amplitude characteristics of microtremor (Part 2): Journal of the Seismological Society of Japan, 24, 26-40, https://doi.org/10.4294/zisin1948.24.1_26.
Poggi, V., and Fäh, D., 2010, Estimating Rayleigh wave particle motion from three-component array analysis of ambient vibrations: Geophys. J. Int., 180, 251-267, doi 10.1111/j.1365-246X.2009.04402.x.
Wathelet, M., 2008, An improved neighborhood algorithm: parameter conditions and dynamic scaling: Geophys. Res. Lett., 35, L09301, doi  10.1029/2008GL033256.
Wathelet, M., Guillier, B., Roux, P., Cornou, C., and Ohrnberger, M., 2018, Rayleigh wave three-component beamforming: Signed ellipticity assessment from high-resolution frequency-wavenumber processing of ambient vibration arrays: Geophys. J. Int., 215(1), 507-523. Doi 10.1093/gji/ggy286.
Wathelet, M., Chatelain, J. L., Cornou, C., Giulio, G. D., Guillier, B., Ohrnberger, M., and Savvaidis, A., 2020, Geopsy: A user-friendly open-source tool set for ambient vibration processing: Seismol. Res. Lett., 91(3), 1878-1889. doi:10.1785/0220190360.