1. JGD
  2. All Volumes and Issues
  3. 2(33)2022
  4. Determination of differential locations and focal mechanism of the 2013-2015. Earthquakes in Trosnyk, Transcarpatians: methodological aspects and analysis of the results

Determination of differential locations and focal mechanism of the 2013-2015. Earthquakes in Trosnyk, Transcarpatians: methodological aspects and analysis of the results

JGD.
2022;
Volume 2(33)2022, Number 2(33)
: 50-63
https://doi.org/10.23939/jgd2022.02.050
Received: August 31, 2022
Authors:
  1. Andriy Gnyp
1
Carpathian Branch of Subbotin Institute of Geophysics of the NAS of Ukraine

The differential and source terms locations of a series of small (1.0<ML<2.5) similar (recurrent) earthquakes that occurred during 2013-2015 near the village of Trosnyk in the south of Transcarpathians were determined. Adaptive filtering was proposed to reduce the effect of correlated noise in records with very low signal-to-noise ratio and to improve the reliability of differential arrivals. The maximum correlation criterion was modified to include the minimum departure from the calculated arrival times. Analysis of the intervals between phase arrivals at pairs of stations was proposed to further reduce the number of problematic arrivals. The sensitivity of the final solution to the network configuration was assessed using the jack-knife principle, when the coordinates are calculated, each time removing one station from the full set. The focal mechanism common to all earthquakes in the series was defined using the polarities of P-wave arrivals at 16 stations. Based on the results of the 3D interpretation of the differential hypocenters, the nodal plane with a strike of 150° was identified as the rupture plane, and the mechanism itself was classified as left-lateral slip with a component of thrust. The epicenter of the strongest earthquake was located almost exactly on the fault of the pre-Neogene basement with a strike parallel to the Carpathian arc, almost the same as the strike of the rupture plane. The axis of compression in the focal mechanism is directed to the east, which is fully consistent with the northeast direction of the general regional field.

recurrent (similar) earthquakes
waveform correlation
differential arrivals
station terms
focal mechanism
fault-block tectonics
tectonic stress.
  1. Davis, J. C. (1986). Statistics and Data Analysis in Geology. John Wiley & Sons, Inc., Second edition.
  2. Efron, B. (1982). The Jackknife, the Bootstrap, and Other Resampling Plans. SIAM. https://doi.org/10.1137/1.9781611970319
  3. Gnyp, A. (2010). Refining locations of the 2005-2006 recurrent earthquakes in Mukacheve, West Ukraine, and implications for their source mechanism and the local tectonics. Acta Geophysica 58 (4), 587–603. https://doi.org/10.2478/s11600-010-0006-9
  4. Gnyp, A. (2013). Recovering Relative Locations of the 2005-2006 Mukacheve Earthquakes from Similarity of their Waveforms at a Single Station. Acta Geophysica 61 (5), 1074–1087. https://doi.org/10.2478/s11600-012-0096-7
  5. Gnyp, A. (2014). On Reproducibility of Relative Locations of Recurrent Earthquakes Recovered from Similarity of their Waveforms at a Single Station. Acta Geophysica 62 (6), 1246–1261. https://doi.org/10.2478/s11600-013-0195-0
  6. Gnyp, A., & Malytskyy, D., (2021). Differential and source terms locations of the 2015 Teresva (East Carpathians) series and their tectonic implications. Acta Geophysica 69 (6), 2099–2112. https://doi.org/10.1007/s11600-021-00655-w, https://rdcu.be/cyPNh
  7. Harris, D. B. (1991). A waveform correlation method for identifying quarry explosions, Bull. seism. Soc. Am. 81(6), 2395–2418. https://doi.org/10.1785/BSSA0810062395
  8. Harris, D. B., & Douglas, A. D. (2021). The geometry of signal space: a case study of direct mapping between seismic signals and event distribution. Geophys. J. Int. 224, 2189–2208. https://doi.org/10.1093/gji/ggaa572
  9. Herrmann, R. B. (1979). FASTHYPO – a hypocenter location program. Earthquake notes 50(2), 25–37. https://doi.org/10.1785/gssrl.50.2.25
  10. Khomenko, , V. I. (1971). Deep Structure of the Transcarpathian Depression. Naukova Dumka. (in Ukrainian)
  11. Khomenko, , V. I. (1987). Deep Structure of the South-West Edge of the East-European platform. Naukova Dumka. (in Russian)
  12. Malytskyy, D. V., Obidina, O. O., Gnyp, A. R., Pavlova, A. Y., & Grytsai, O. D. (2017). Tectonic stresses in the area of Solotvyno deep, Eastern Carpathians, from focal mechanisms of local earthquakes. 16th International Conference on Geoinformatics - Theoretical and Applied Aspects, 15-17 May 2017, Kyiv, Ukraine, Conference Paper 11137_ENG. https://doi.org/10.3997/2214-4609.201701868
  13. Malytskyy, D., Murovska, A., Obidina, O., Gnyp, A., Grytsai, O., Pavlova, A., & Pugach, A. (2017). Determining the stress field in earth's crust from source mechanisms of local earthquakes in the Transcarpatians. Visnyk of Taras Shevchenko National University of Kyiv: Geology. 3(78), 36-45. http://doi.org/10.17721/1728-2713.78.05
  14. Nadeau, R. M., & McEvilly, T. V. (1999). Fault slip rates at depth from recurrence intervals of repeating microearthquakes. Science 285(5428), 718–721. https://doi.org/10.1126/science.285.5428.718
  15. Poupinet, G., Ellsworth, W.L., & Fréchet, J. (1984). Monitoring velocity variations in the crust using earthquake doublets: An application to the Calaveras Fault, California. J. Geophys. Res. 89, B7, 5719–5731. https://doi.org/10.1029/JB089iB07p05719.
  16. Pronishyn, R. S., & Pustovitenko, B. G. (1982). Some aspects of seismic “climate and weather” in the Transcarpathians. Izv. Acad. Sci. USSR, Phys. Solid Earth 18, 74–81. (in Russian).
  17. Robinson, D. J, Sambridge, M., Sneider, R., & Hauser, J. (2013). Relocating a Cluster of Earthquakes Using a Single Seismic Station. Bull. Seism. Soc. Am. 108(6), 3057–3072. https://doi.org/10.1785/0120130004
  18. Robinson, D. J, Sambridge, M., & Sneider, R. (2007). Constraints on coda wave interferometry estimates of source separation: The acoustic case. Explor. Geophys. 38(3), 189–199. https://doi.org/10.1071/EG07019
  19. Robinson, D. J, Sneider, R., & Sambridge, M. (2007). Using coda wave interferometry for estimating the variation in source mechanism between double couple events. J. Geophys. Res. 112(В12), B12302. https://doi.org/10.1029/2007JB004925
  20. Shearer, P. M. (1997). Improving local earthquake locations using L1 norm and waveform cross correlation: Application to the Whittier Narrows, California, aftershock sequence. J. Geophys. Res. 102(B4), 8269–8283. https://doi.org/10.1029/96JB03228
  21. Shearer, P., Hauksson, E., & Lin, G. (2005). Southern California hypocenter relocation with waveform cross-correlation. Part2: Results using source-specific station terms and cluster analysis. Bull. Seism. Soc. Am. 95(3), 904–915. https://doi.org/10.1785/0120040168
  22. Sibson, R. (1973). SLINK: an optimally efficient algorithm for the single-link cluster method. The Computer Journal. British Computer Society 16 (1): 30–34. https://doi.org/10.1093/comjnl/16.1.30
  23. Starodub, G., & Gnyp, A. (1999). Models of the Earth’s Crust Structure in the East Carpathian Region determined from Inversion of Farfield P-waveforms. Acta Geophysica Polonica 47(4), 375–400. Id. YADDA: bwmeta.element.baztech-article-BSL6-0006-0061
  24. Tibuleac, I. M., & Herrin, E. (1999). Lower mantle heterogeneity beneath the Caribbean Sea. Science 285(5434), 1711–1715. https://doi.org/10.1126/science.285. 5434.1711
  25. Verbytskyi, Yu.T., Gnyp, A. R., Narivna, M. M., Novotna, O. M., & Yarema, I. I. (2011). Identification of quarry blasts in the Carpathian region of Ukraine by the criterion of similarity of their waveforms. Geodynamics 1(10), 103–109. https://doi.org/10.23939/jgd2011.01.103
  26. Verbickij, S. T, Pronishin, R. S., Verbickij, Yu. T,. Chuba, M. V., Keleman, I. N., & Stetskiv, A. T. (2014). Seismological bulletin of Ukraine for 2013. Sevastopol, NPC EHkosi-Gidrofizika, 92–158. (in Russian)
  27. Verbitsky, S. T., Pronishin, R. S., Procopishin, V. I., Stetskiv, A. T., Chuba, M. V., Nischimenko, I. M., & Keleman, I. N. (2014). The seismicity of the Carpathians in 2014. Scientific Notes of V.I. Vernadsky Crimean Federal University. Geography. Geology 27 (66), № 2, 87–151. (in Russian)
  28. Verbitsky, S. T., Pronishin, R. S., Procopishin, V. I., Stetskiv, A. T., Chuba, M. V., Nischimenko, I. M., & Keleman, I. N. (2016), The seismicity of the Carpathians in 2015. Scientific Notes of V.I. Vernadsky Crimean Federal University. Geography. Geology 2(68), № 4, 69–219. (in Russian)
  29. Waldhauser, F, & Ellsworth, L. W. (2000). A Double-Difference Earthquake Location Algorithm: Method and Application to the Northern Hayward Fault. California. Bull. Seism. Soc. Am. 90(6), 1353–1368. https://doi.org/10.1785/0120000006
  30. Wessel, P., Smith, W.H.F., Scharroo, R., Luis, J. F., & Wobbe, F. (2013). Generic mapping tools: improved version released. EOS Trans. AGU. 94, 409–410. https://doi.org/10.1002/2013EO450001