Comparative analysis of recurrent earthquakes of 06.01.2012 and 10.01.2012 in the Transcarpathians

2013;
: pp. 225 - 227
https://doi.org/10.23939/jgd2013.02.225
Received: August 11, 2013
1
Carpathian Branch of Subbotin Institute of Geophysics of NAS of Ukraine
2
Carpathian Branch of Subbotin Institute of Geophysics of NAS of Ukraine
3
Carpathian Branch of Subbotin Institute of geophysics of NAS of Ukraine
4
Department of seismicity of the Carpathian region of the Subbotin Institute of geophysics of National Academy of Sciences of Ukraine
5
Carpathian branch of Subbotin Institute of geophysics of NAS of Ukraine

Purpose. The purpose of this paper is to show the importance of the additional information to determine the focal mechanisms of earthquakes in the Carpathian region of Ukraine, and also to determine the focal mechanisms and the spectral parameters of recurrent earthquakes. Methodology. The graphic method is proposed to determine the focal mechanisms of earthquakes in the region with a small seismic activity. This method is based on the distribution of the longitudinal P- wave polarities into compressive and extensive zones devised by nodal planes. The fuzzy arrivals of P- waves at the stations and the value of the S/P- wave amplitude ratio are important parameters witch define the placement of the station relative to nodal planes. The information about the recurrent earthquakes, that is, about the similarity of the waveforms, and therefore, about the same sign at the station for different events, is used to determine the signs of the P – waves arrivals. Results. The results of the focal mechanism determination of two events with similar waveforms that occurred in the area of NNP "Synevyr" (Transcarpathia): 06.01.2012, at 04:34:10.464, (φ=48.5309, λ=23.8365, h=5.1 km) and 10.01.2012, 12:12:55.584, (φ=48.5367, λ=238378, h=5.7 km) are presented. The focal mechanisms were determined with the use of graphic method and complete records at the stations and protocols about these events. The values of the seismic moment, the geometrical dimension of the source, the average source dislocation, the stress drop, the seismic energy and the magnitude ML were obtained for both events. Originality. For the first time the focal mechanisms of earthquakes 06.01.2012 (φ=48.5309, λ=23.8365, h=5.1 km), 10.01.2012 (φ=48.5367, λ=238378, h=5.7 km) are determined by using the graphic method and additional information about the logarithm of the S/P- wave amplitude ratio and about the recurrent earthquakes, and also obtained the spectral parameters of these earthquakes. Practical significance. The results of this work will be used to further study the seismicity of the Carpathian region, determine the focal mechanisms of earthquakes and the study of stress-strain state of rocks in this region.

  1. Aki K., Richards P.G. Kolichestvennaja sejsmologija. Teorija i metody: v 2 t. [Quantitative Seismology. Theory and Techniques: in 2 v.]. Moscow, Mir, 1983, 520 p.
  2. GnypA.R. Utochnennya vohnyshch povtornykh zemletrusiv u Zakarpatti [ Refining the sources of recurrent earthquakes in the Transacarpatians] Geodynamics, 2011, № 2 (11), pp. 66-68.
  3. Malytskyy D.V., Hrytsai O.D., Muyla O.O. Osoblyvosti pobudovy mekhanizmiv vohnyshch mistsevykh zemletrusiv na prykladi Berehivs'koyi podiyi 23.11.2006r.[ The features of the construction of the focal mechanisms of local earthquakes using the example of an event near Beregovo 23.11.2006], Visnyk KNU, Heolohiya [Bulletin of Taras Shevchenko name Kyiv National University, Geology], 2013,no. 60, pp. 37-41.
  4. Personal'nyj Blog Grichuha Konstantina Vasil'evicha Available at: http://grinikkos.com/view_post.php?Id = 153
  5. Baumbach M., Bormann P. Determination of source parameters from seismic spectra. Potsdam, 2011, doi: 10.2312/ GFZ.NMSOP-2_EX_3.4.
  6. Cronin V. A Draft Primer on Focal Mechanism Solutions for Geologists. Baylor University,2004.
  7. Hardebeck J.L., Shearer P.M. Using S/P Amplitude Ratios to Constrain the Focal Mechanisms of Small Earthquakes. Bulletin of the Seismological Society of America, 2003, vol. 93, no.6, pp. 2434-2444. https://doi.org/10.1785/0120020236