SEASONAL VARIATIONS OF AMPLITUDE-FREQUENCY PATTERNS OF LOCAL AMBIENT NOISES BY BAIKAL NETWORK SEISMIC STATION DATA

Purpose. The purpose of the paper is evaluation and analysis of the amplitude-frequency patterns of background microseisms (local ambient noises) and their possible seasonal variations in the territory of the Baikal seismic zone. Methods. The method of spectral relations of the vertical and horizontal components of the microseism (H/V-ratio) or Nakamura method is used. The continuous seismic recording data obtained by 23 short-period seismic stations of the Baikal Branch of the Federal Research Centre “Single Unified Geophysical Survey of the Russian Academy of Science” located in the Baikal seismic zone are used as an input material for the analysis. Only long segments of seismic records with the duration of at least 1 hour have been selected for the analysis in order to exclude possible random errors related to human-made noises, earthquakes, industrial explosions, etc. Results. The obtained curves of H/V-ratios and their seasonal variations characterize the amplitude-frequency patterns of local ambient noises in the frequency range from 0.5 to 10.0 or 20.0 Hz depending on the type of the recording equipment used. Conclusions. The obtained H/V-ratio curves can be conditionally divided into two groups: stable and featuring significant seasonal variations. The first group includes the stations with stable amplitude-frequency characteristics of the microseismic signal, which do not depend on the season. The second group includes the stations for which the H/V-ratio curves demonstrating significant seasonal variations have been obtained. Having compared the position of the seismic stations and the obtained H/V-ratio curves, the authors identified the dependence of the amplitude-frequency characteristics of the microseismic signal on their local conditions in the station setup area (at the outcrops of bedrock, in the zone of large active faults or in the rift depressions with a thick sedimentary cover).

Baikal seismic zone, amplitude-frequency content of the seismic signal, microseisms (ambient noise), Nakamura method, spectral analysis

1. Borcherdt R.D. Effects of local geology on ground motion near San Francisco Bay. Bulletin of the Seismological Society of America, 1970, vol. 60, рр. 29–61.

2. Borcherdt R.D., Glassmoyer G. On the characteristics of loсal geology and their influence on ground motions generated by the Loma Prieta earthquake in the San Francisco Bay region, California. Bulletin of the Seismological Society of America, 1992, vol. 82, рр. 603–641.

3. Andrews D.J. Objective determination of source parameters and similarity of earthquakes of different sizes. Earthquake Source Mechanics. Washington: American Geophysical Union, 1986, рр. 259–268.

4. Field E.H., Jacob K.H. The theoretical response of sedimentary layers to ambient seismic noise. Geophysical Research Letters, 1993, vol. 20, рр. 2925–2928.

5. Lermo J.F., Chavez-Garcia F.J., Are microtremors useful in site response evaluation? Bulletin of the Seismological Society of America, 1994, vol. 84, рр. 1350–1364.

6. Drouet S., Chevrot S., Cotton F., Souriau A. Simultaneous Inversion of Source Spectra, Attenuation Parameters, and Site Responses: Application to the Data of the French Accelerometric Network. Bulletin of the Seismological Society of America, 2008, vol. 98, рр. 198–219.

7. Langston C.A. Structure under Mount Rainier, Washington, inferred from teleseismic body waves. Journal of Geophysical Research, 1979, vol. 84, рр. 4749–4762.

8. Nakamura Y. A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface. Quarterly Report of Railway Technical Research Institute, 1989, vol. 30, рр. 25–33.

9. Nogoshi M., Igarashi T. On the amplitude characteristics of microtremor (part 2). Journal of the Physical Society of Japan, 1971, vol. 24, рр. 26–40.

10. Field E.H., Jacob K.H. A comparison and test of various site response estimation techniques, including three that are non reference-site dependent. Bulletin of the Seismological Society of America, 1995, vol. 86, рр. 991–1005.

11. Lachet C., Hatzfeld D., Bard P.-Y., Theodulidis N., Papaioannou C., Savvaidis A. Site effects and microzonation in the city of Thessaloniki (Greece): comparison of different approaches. Bulletin of the Seismological Society of America, 1996, vol. 86, рр. 1692–1703.

12. Bonilla L.F., Steidl J.H., Lindley G.T., Tumarkin A.G., Archuleta R.J. Site amplification in the San Ferdinando Valley, California: variability of site effect estimation using S-wave, coda, and H/V methods. Bulletin of the Seismological Society of America, 1997, vol. 87, рр. 710–730.

13. Kondorskaya N.V., Shebalin N.V. Novyi katalog sil'nykh zemletryasenii na territorii SSSR s drevneishikh vremen do 1975 g. [A new catalog of strong earthquakes on the territory of the USSR from ancient times to 1975]. Moscow: Nauka Publ., 1977, 536 р. (In Russian).

14. Gordienko I.V. Metallogeny of various geodynamic settings in the MongolTransbaikalia region. Geologija i mineral'no-syr'evye resursy Sibiri [Geology and mineral resources of Siberia], 2014, vol.S3-1, pp. 7–13. (In Russian).

15. Masal'skii O.K., Chechel'nitskii V.V., Gileva N.A. Sovremennoe sostoyanie seismicheskikh nablyudenii v Pribaikal'e [Current state of seismic observations in the Baikal region]. Materialy II Mezhdunarodnoi seismologicheskoi shkoly “Sovremennye metody obrabotki i interpretatsii seismologicheskikh dannykh” [Materials of the Second International Seismological School: Modern methods of seismological data processing and interpretation]. Obninsk: Geophysical Survey RAS Publ., 2007, рр. 140–144. (In Russian).

16. Solonenko V.P., Khil'ko S.D., Khromovskikh V.S. Seismicheskoe raionirovanie Vostochnoi Sibiri i ego geologogeofizicheskie osnovy [Seismic zoning of Eastern Siberia and its geological and geophysical foundations]. Novosibirsk: Nauka, 1977, 304 р. (In Russian).

17. SESAME group. Final report on measurements guidelines, LGIT Grenoble, CETE Nice, WP02, H/V technique: experimental conditions, 2003. Available at: http://sesame-fp5.obs.ujf-grenoble.fr/Delivrables/D08-02_Texte.pdf

18. Chernykh E.N., Dobrynina A.A. Variations of the microseism spectral ratios for Baikal seismic station network. Geophysical Research Abstracts, 2010, vol. 12, EGU2010-479. Available at: https://meetingorganizer.copernicus.org/EGU2010/EGU2010-479.pdf

19. Bard P.-Y. Effects of surface geology on ground motion: recent results and remaining issues. 10th European Conference on Earthquake Engineering, Duma (Editor). Rotterdam: Balkema, 1995, рр. 305–323.

20. Tabulevich V.N., Drennova N.N., Potapov V.A., Chernykh E.N. The effect of storm microseisms on seismicity manifestation in the coastal zone of lake Baikal. Geologiya i geofizika [Russian Geology and Geophysics]. 2001, vol. 42, no. 8, pp. 1271–1278. (In Russian).

21. Drennov A.F., Dzhurik V.I., Serebrennikov S.P., Drennova N.N. Influence of the upper section on the amplitudefrequency content of a seismic signal by the example of seismic stations in Pribaikalye and Trans-Baikal area. Seismicheskie pribory [Seismic Instruments], 2010, vol. 46, no. 2. рр. 15–25. (In Russian).

22. Sankov A.V., Dobrynina A.A., Chernykh E.N., Sankov V.A., Shagun A.N. Investigation of the boundary and internal fault zones of Tunka basin (Baikal rift system) using HVSR method. Proceedings of the International Conference on Astronomy and Geophysics in Mongolia. Ulaanbaatar, Mongolia, 20–22 July 2017. Ulaanbaatar: Mongol Altay printing Co Ltd, 2017, рр. 231–234.