ВИЗНАЧЕННЯ МЕХАНІЗМУ ВОГНИЩА ЗЕМЛЕТРУСУ В РАЙОНІ АЛЬБЕРТИ, КАНАДА (Φ = 58.16°N, Λ = - 115.25°E, MW =3.98)

Д. Малицький; О. Грицай; О. Обідіна; А. Павлова

doi:10.17721/1728-2713.70.05

Authors

D. Malytskyy Carpathian Branch of Subbotin Institute of Geophysics National Academy of Sciences of Ukraine 3-b Naukova St., Lviv, Ukraine, 79060
O. Hrytsai Carpathian Branch of Subbotin Institute of Geophysics National Academy of Sciences of Ukraine 3-b Naukova St., Lviv, Ukraine, 79060
O. Obidina Carpathian Branch of Subbotin Institute of Geophysics National Academy of Sciences of Ukraine 3-b Naukova St., Lviv, Ukraine, 79060
A. Pavlova Carpathian Branch of Subbotin Institute of Geophysics National Academy of Sciences of Ukraine 3-b Naukova St., Lviv, Ukraine, 79060

DOI:

https://doi.org/10.17721/1728-2713.70.05

Keywords:

focal mechanism, correlation analysis, nodal plane, the depth of earthquake source

Abstract

The aim of this paper is to determine focal mechanism of earthquake occurred in Alberta (Canada) province by using graphic method and to clarify the focus depth by doing correlation analysis of real and artificial seismograms. The graphic method is proposed for for determining the focal mechanism of earthquake in the region with low seismic activity. This method is based on P-waves polarity distribution into zones of compression and extension, and division of nodal planes. Fuzzy P-waves arrivals in the station and the value of the ratio of the S-wave amplitude to Pwave are important parameters. They define the relative location to the nodal plane. To use the graphical method the correct velocity model of the medium and clear records of the stations might be used. The results of construction of focal mechanism in Alberta (Canada) as the the region with low seismic activity are discussed. The focal mechanisms were constructed by graphic method with using the complete records from the station and documents about these records for the different depth of the source occurence. The comparative analysis of real and artificial seismograms is made. It is determined that seismic event occurred at a depth of 6 km. For the first time the focal mechanism of the earthquake in Alberta is determined. The depth of the earthquake occurrence is specified by correlation analysis between the actual and artificial tracks (seismogram). The highest correlation coefficient is observed between real records and artificial seismograms calculated for the earthquake depth of 6 km, which indicates the depth of the earthquake source determined in this work. The results of this paper will be used for further study of Carpathian region seismicity, determination of the focal mechanisms of earthquake and analysis of stress-strain state of rocks in this region.

References

Malytskyy, D. Muyla, O. Pavlova, A. Grytsai, O. (2013). Determinationof focal mechanism of the earthquake in Transcarpathia. Visnyk of Taras Shevchenko National University of Kyiv: Geology, 4(63), 38-44. [in Ukrainian].

Voronina, E.V. (2004). Mechanics earthquake: Special Course. Moscow: Publishing House. Def. Faculty of Moscow State University. [in Russian].

Kasahara, K. (1985). Mechanics earthquakes. Moscow: Mir. [in Russian].

Balakina, L.M. Vvedenskaya, A., Golubev, N.L., Misharina, A., Shirokov, E.I. (1972). Elastic stress field of the Earth and earthquake focal mechanisms. Moscow: Science. [in Russian].

Adamova, P., Sokos, E., Zahradnik, J. (2009). Problematic nondouble-couple mechanism of the 2002 Amfilochia Mw5 earthquake. Western Greece. J. Seismol.,13, 1-12.

Aki, K., Richards, P.G. (2002). Quantitative Seismology, 2ndedn. Sausalito, California: University Science books.

Baumbach, M., Bormann, P. (2011). New Manual of Seismological Observatory Practice. Determination of source parameters from seismic spectra. Potsdam: Deutsches GeoForschungsZentrum GFZ.

Cronin, V.S. Draft Primer on Focal Mechanism Solutions for Geologists. Retrieved from http://serc.carleton.edu/files/NAGTWorkshops/ structure04/Focal_mechanism_primer.pdf.

Ebel, J.E., Bonjer, K.P. (1990). Moment tensor inversion of small earthquakes in southwestern Germany for the fault plane solution. Geophys. J. Int., 101, 133-146.

Fojtikova, L., Vavrycuk, V., Cipciar, A., Madaras, J. (2010). Focal mechanisms of micro-earthquakes in the Dobra Voda seismoactive area in the Male Karpaty Mts. (Little Carpathians), Slovakia. Tectonophysics, 492, 213-229.

Julian, B.R., Miller, A.D., Foulger, G.R. (1998). Non-double-couple earthquakes: 1. Theory. Rev. Geophys, 36, 525-549.

Madariaga, R. (1976). Dynamics of an expanding circular fault. Bull. Seism. Soc. Am., 66, 639-667.

Maruyama, T. (1966). On two-dimensional elastic dislocations in an infinite and semi-infinite medium. Bull. Earthq. Res. Inst., 44, 811-871.

Hardebeck, J.L., Shearer, P.M. (2003). Using S/P Amplitude Ratios to Constrain the Focal Mechanisms of Small Earthquakes. Bull. Seism. Soc. Am., 93(6), 2434-2444.

Nakano, H. (1923). Notes on the nature of the forces which giverise to the earthquake motions.Seism. Bull. Centr. Metrol. Observ. of Japan., 1, 92-120.

Pavlova, A., Hrytsai, O., Malytskyy, D. (2014).Ways of Determining the Focal Mechanisms in the Carpathian Region of Ukraine. Journal of Earth Science and Engineering, 4(1), 54-71.