МЕХАНІЗМИ ВОГНИЩ ЗЕМЛЕТРУСІВ ТА ПОЛЕ НАПРУЖЕНЬ СОЛОТВИНСЬКОЇ ЗАПАДИНИ ЗАКАРПАТТЯ

Д. Малицький; А. Муровська; О. Гінтов; А. Гнип; О. Обідіна; С.  Мичак; О. Грицай; А. Павлова

doi:10.17721/1728-2713.77.05

Authors

D. Malytskyy Carpathian Branch of the Subbotin Institute of Geophysics NAS of Ukraine 3-b Naukova Str., Lviv, 79060, Ukraine
A. Murovska Subbotin Institute of Geophysics NAS of Ukraine 32 Palladina Ave., Kyiv, 03680, Ukraine
O. Gintov Subbotin Institute of Geophysics NAS of Ukraine 32 Palladina Ave., Kyiv, 03680, Ukraine
A. Gnyp Carpathian Branch of the Subbotin Institute of Geophysics NAS of Ukraine 3-b Naukova Str., Lviv, 79060, Ukraine
O. Obidina Carpathian Branch of the Subbotin Institute of Geophysics NAS of Ukraine 3-b Naukova Str., Lviv, 79060, Ukraine
S. Mychak Subbotin Institute of Geophysics NAS of Ukraine 32 Palladina Ave., Kyiv, 03680, Ukraine
O. Grytsai Carpathian Branch of the Subbotin Institute of Geophysics NAS of Ukraine 3-b Naukova Str., Lviv, 79060, Ukraine
A. Pavlova Carpathian Branch of the Subbotin Institute of Geophysics NAS of Ukraine 3-b Naukova Str., Lviv, 79060, Ukraine

DOI:

https://doi.org/10.17721/1728-2713.77.05

Keywords:

earthquake source, stress tensor, principal stresses, cinematic method, outcrops, normal stress, shear stress, Michael's method

Abstract

In the paper, two different methods are presented for evaluation of the stress field in the Solotvyno depression, the part of the Transcarpathians trough. In one method, stress field is determined by inverting the focal mechanisms of local earthquakes, in the other one – from data of field tectonophysics investigations. (In the Michael's method, to determine principal stresses from source mechanisms it is needed to know which of the nodal planes exactly coinsides with the fault plane.) In the paper, a Vavrychuk's version of Michael's method and his fault instability constraint is used to identify the fault planes and the directions of principal stresses σ1, σ2, σ3 for 30 earthquakes which occurred in the area of Tyachiv during the period from 19.07.2015 to 06.08.2015. Focal mechanisms of the Tyachiv earthquakes are determined by graphic method, from polarities of first arrivals of P-waves, emergence angles (or incidence angles) at each of the stations and station azimuths. To determine principal axes of stress tensor from the data of tectonophysics investigations the cinematic approach is used for processing of tectonic slickensides with slide grooves and the structuralparagenetic method for processing of ruptures without the traces of displacement. In the paper, eight outcrops from the area of Solotvyno depression are analyzed: three of them are from the zone of Pienniny cliffs; three outcrops are located in the area of vulcanite formation in the Vyhorlat-Huta range, and two outcrops are from the Solotvyno depression itself. In all the outcrops, the types and orientations of recovered stress fields are found to recur. In general, stress fields of strike type and of faulting type prevail. The fields of faulting type are characterized by south-western orientation of tension axis σ3 and are similar to the mechanisms of Tyachiv earthquakes. Age correlation of the recovered stress fields is difficult to estimate only from field observations. That is why it is important to correlate the stress fields recovered in tectonophysics studies and from earthquake mechanisms. That enables to evaluate the current stress field.

References

Bubnyak, I.N., Vyhot Yu, M., Nakapelyuh, M.V. (2013). Stress-strain state of the south-eastern part of Skibovogo and Borislav-Pokutsko covers Ukrainian Carpathians. Geodynamics & Tectonophysics, 3(4), 313–326. [in Russian].

Gintov, O.B. (2005). Field geotektonofizika and its application in the study of crustal deformation in Ukraine. Kiev: Feniks, 572 р. [in Russian].

Gintov, O.B., Bubnyak, I.N., Vyhot, Yu. M., Murovska, A.V., Nakapelyuh, M. V., Shlapisnkyy, B.E. (2014). Tectonophysical and palinspastic cuts Ukrainian Carpathians along geotraverse DOBRE-3 (PANCAKE). Geophysical Journal, 3 (36), 3–33. [in Russian].

Gintov, A., Murovskaya, A., Yegorova, T., Volfman, Yu., Tsvetkova, T., Buhayenko, I., Kolesnikov, E., Ostrovnoy, A., Bubniak I., Farfulyak, L., Amashukely, T. (2015). The deep seismogenic zone of Vrancea as an indicator of the geodynamic process. Geophysical journal, 3 (27), 22-49. [in Russian].

Ukrainian Carpathians Geological Map, scale 1: 100 000. IvanoFrankivsk, Lviv, Chernivtsi region of Ukraine. (2007) Compiled by Glushko, V., Kuzovenko, V.V., Shlapinsky, V.E. Editor Yu. Z. Krupski. Report of JSC "Nadra Concern". Report of JSC "Nadra Concern". JSC "Concern Nadra" Foundation. Kiev, 228 р. [in Russian].

Gnyp, A., Nischimenko, I. (2016). Identification of repeated earthquakes Tiachiv 2015 series. Materials Conference. Lviv, 25-28. [in Ukrainian].

Gushchenko, O.I. (1979). The method of kinematic analysis of the structures of destruction in the reconstruction of tectonic stress fields. Stress field and deformation in the lithosphere. M.: Nauka, 7-25. [in Ukrainian].

Malytskyy, D., Grytsay, O., Muyla, O. (2014). Determining the focal mechanism of earthquake in the Carpathian region. Geophysical journal, 4(36), 118 – 135. [in Ukrainian].

Murovska, A.V., Nakapelyuh, M. V., Vyhot, Yu. M., Shlapisnkyy B.E., Bubnyak I.N., Mychak S.V. (2016) Kinematic evolution of the Valais area in the Cenozoic rocks. (Ukraiskie Carpathians). Geophysical Journal, 5. [in Russian].

Proshyshyn, R.S., Kuznetsova, V.G. (2011). How the spatial distribution of seismic tectonic structure of the Transcarpathian basin, Geodynamics, 2 (11), 254-256. [in Ukrainian].

Murovska, A., Іppolit, Zh.-K., Sheremet, Ye., Yegorova, T., Wolfman, Yu., Kolesnikova, K. (2015). Deformation structure and stress field southwestern Crimea in the context of the evolution of the Western Black Sea. Geodinamics , 1, 10-29. [in Ukrainian].

Seismological Bulletin of Ukraine for 2015 (2015). Department of seismicity of Carpathian region IGPh NAS of Ukraine. Lviv, 295 р. [in Ukrainian].

Tretiak, C.R., Maksymchuk, Yu. V., Kutas, R.I. (Ed.) (2015). Modern geodynamics and geophysical fields Carpathians and adjacent territories. Lviv: Lviv. Polytechnics, 418 р. [in Ukrainian].

Shevchuk V., Vasilenko A. (2015). Tectonophysical conditions of late stages of development of the middle link of the Transcarpathian deep fault. Geophysical Journal, 5(37), 121-128. [in Ukrainian].

Angelier, J. (1984). Tectonic analysis of fault slip data sets. J. Geophys. Res., 8 (B7), 5835 – 5848.

Angelier, J. (2002). Inversion of earthquake focal mechanisms to obtain the seismotectonic stress IV – a new method free of choice among nodal lines. Geophys. J. Int., 150, 588-609.

Arnold, R., Townend, J. (2007). A Bayesian approach to estimating tectonic stress from seismological data. Geophys. J. Int., 170, 1336-1356.

Bott, M.H.P. (1959). The mechanics of oblique slip faulting. Geol. Mag., 96, 109-117.

Byerlee, J. (1978). Fiction of rocks. Pure appl. Geophys., 116, 615-626.

Csontos, L., Vörös, A. (2004). Mesozoic plate tectonic reconstruction of the Carpathian region, Palaeoecology, 210 (1), 1-56. Palaeogeography, Palaeoclimatology,

Devlaux, D., Sperner, B. (2003). New aspects of tectonic stress inversion with reference to the TENSOR program, New insights into Structural interpretation and Modelling. Geological Society. – London: Special Publications, 75–100.

Fodor, L., Csontos, L., Bada, G., Györfi, I., Benkovics, L. (1999). Tertiary tectonic evolution of the Pannonian basin system and neighbouring orogens: a new synthesis of paleostress data. In: B. Durand et al. (Editors). The Mediteranean basins: Tertiary extension within the Alpine orogen. Geol. Soc. of London Spec. Publ., 156, 295–334.

Gephart, J.W., Forsyth, D.W. (1984). An improved method for determining the regional stress tensor using earthquake focal mechanism data: application to the San Fernando earthquake sequence. J. geophys. Res., 89, 9305-9320.

Hardebeck, J.L., Michael, A.J. (2006). Damped regional-scale stress inversions: methodology and examples for southern California and Coalinga aftershock sequence, J. geophys. Res., 111, B11310. doi: 10.1029/2005JB004144.

Horváth, F., Bada, G., Szafián, P., Tari, G., Ádám, A., Cloetingh, S. (2006). Formation and deformation of the Pannonian Basin: constraints from observational data. In: Gee D. and Stephenson R. (Eds.). European Lithosphere Dynamics, Geological Society Memoir, 32, 191-206.

Lay, T., Wallace, T.C. (1995). Modern Global Seismology. Academic Press.

Lund, B., Slunga, R. (1999). Stress tensor inversion using detailed microearthquake information and stability constraints: application to Olfus in southwest Iceland. J. geophys. Res., 104, 14947-14964.

Malytskyy, D., Muyla, O., Pavlova, A., Hrytsai, O. (2013). Determining the focal mechanism of an earthquake in the Transcarpathian region of Ukraine. Visnyk KNU, Geology, 4(63), 38-44.

Maury, J., Cornet, F.H. & Dorbath, L. (2013). A review of methods for determining stress fields from earthquake focal mechanisms: application to the Sierentz 1980 seismic crisis (Upper Rhine graben). Bull. Soc. Geol. France, 184(4-5), 319-334.

Vavrychuk, V. (2014). Iterative joint inversion for stress and fault orientations from focal mechanisms. Geophys. J. Int., 199, 69-67. 31. Wallace, R.E. (1951). Geometry of shearing stress and relation to faulting. J. Geol., 59, 118-130.