Model study of influence of internal stresses on deformation and seismic processes in convergent plate boundary zones by the example of Lake Baikal ice cover
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Інститут геофізики ім. С.I. Субботіна НАН України
2010
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| Назва видання: | Геофизический журнал |
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| Цитувати: | Model study of influence of internal stresses on deformation and seismic processes in convergent plate boundary zones by the example of Lake Baikal ice cover / S. Psakhie, E. Shilko, S. Astafurov, A. Dimaki, V. Ruzhich // Геофизический журнал. — 2010. — Т. 32, № 4. — С. 134-135. — Бібліогр.: 3 назв. — англ. |
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irk-123456789-1030892016-06-14T03:04:17Z Model study of influence of internal stresses on deformation and seismic processes in convergent plate boundary zones by the example of Lake Baikal ice cover Psakhie, S. Shilko, E. Astafurov, S. Dimaki, A. Ruzhich, V. 2010 Article Model study of influence of internal stresses on deformation and seismic processes in convergent plate boundary zones by the example of Lake Baikal ice cover / S. Psakhie, E. Shilko, S. Astafurov, A. Dimaki, V. Ruzhich // Геофизический журнал. — 2010. — Т. 32, № 4. — С. 134-135. — Бібліогр.: 3 назв. — англ. 0203-3100 http://dspace.nbuv.gov.ua/handle/123456789/103089 en Геофизический журнал Інститут геофізики ім. С.I. Субботіна НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| format |
Article |
| author |
Psakhie, S. Shilko, E. Astafurov, S. Dimaki, A. Ruzhich, V. |
| spellingShingle |
Psakhie, S. Shilko, E. Astafurov, S. Dimaki, A. Ruzhich, V. Model study of influence of internal stresses on deformation and seismic processes in convergent plate boundary zones by the example of Lake Baikal ice cover Геофизический журнал |
| author_facet |
Psakhie, S. Shilko, E. Astafurov, S. Dimaki, A. Ruzhich, V. |
| author_sort |
Psakhie, S. |
| title |
Model study of influence of internal stresses on deformation and seismic processes in convergent plate boundary zones by the example of Lake Baikal ice cover |
| title_short |
Model study of influence of internal stresses on deformation and seismic processes in convergent plate boundary zones by the example of Lake Baikal ice cover |
| title_full |
Model study of influence of internal stresses on deformation and seismic processes in convergent plate boundary zones by the example of Lake Baikal ice cover |
| title_fullStr |
Model study of influence of internal stresses on deformation and seismic processes in convergent plate boundary zones by the example of Lake Baikal ice cover |
| title_full_unstemmed |
Model study of influence of internal stresses on deformation and seismic processes in convergent plate boundary zones by the example of Lake Baikal ice cover |
| title_sort |
model study of influence of internal stresses on deformation and seismic processes in convergent plate boundary zones by the example of lake baikal ice cover |
| publisher |
Інститут геофізики ім. С.I. Субботіна НАН України |
| publishDate |
2010 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/103089 |
| citation_txt |
Model study of influence of internal stresses on deformation and seismic processes in convergent plate boundary zones by the example of Lake Baikal ice cover / S. Psakhie, E. Shilko, S. Astafurov, A. Dimaki, V. Ruzhich // Геофизический журнал. — 2010. — Т. 32, № 4. — С. 134-135. — Бібліогр.: 3 назв. — англ. |
| series |
Геофизический журнал |
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Model study of influence of internal stresses
on deformation and seismic processes in convergent plate
boundary zones by the example of Lake Baikal ice cover
S. Psakhie1, E. Shilko1, S. Astafurov1, A. Dimaki1, V. Ruzhich2, 2010
1Institute of Strength Physics and Materials Sciences, SB RAS, Tomsk, Russia
shilko@ispms.tsc.ru
2Institute of the Earth's Crust, SB RAS, Irkutsk, Russia
ruzhich@crust.irk.ru
An important class of problems in mechanics of heterogeneous media (including geological ones)
isstudying regularities of deformation and destruction of specific quasi-two-dimensional (plate) systems,
whose structural elements are mainly located in one plane. A classical example of a natural plate medi-
um is the lithosphere. Macroscopic geometry of the lithosphere and mechanic characteristics of sub-
strate stimulate its fragmentation (breaking into ensemble of interacting plates) and appearance of
specific deformation mechanisms, connected with removal of mature material from the plane of defor-
mation (subduction) and formation of a new one (spreading). Studying zones of subduction and their
influencing the stressed medium condition is one of the most urgent geotectonic and geodynamic prob-
lems, connected with understanding regularities of deformation processes in the lithosphere. Due to
huge spatial and temporal scale of deformation pro-cesses in such zones, one of the perspective ways to
analyze their peculiarities is physical modeling with the help of simplified model systems. As the
results of previous researches have shown [Hamagu-chi, Goto,1978; Psakhie et al., 2009], a perspec-
tive model medium for studying tectonic processes (in particular, the conditions of subduction zone for-
mation and development) is a plate ice cover of large water reservoirs. The present paper is devoted to
evaluation of typical level of stress in plate medium and the role of underride/subduction as relaxation
mechanism by the example of Lake Baikal ice cover. The conducted full-scale research have shown that
regularities of localization of interplate defor-mations in the Lake Baikal ice cover are determined by
distribution, value and sign of internal plate stres-ses. In particular, convergent interplate movements,
leading to forming and developing underride zones (analogous to subduction zones in the lithosphere),
are the results of increase in positive (stretching) stresses. Decrease in value and change of stress
sign to negative result in partial consolidation of blocks consisting in "healing" some of previously
active interfaces and localization of small, mainly divergent interblock movements on the rest of the
interfaces. These regularities are consistent with modern conception on the connection between sign
and value of regional tectonic stresses near inter-plate boundaries in the lithosphere and type of rela-
tive displacement of tectonic plates (convergent or divergent). It is important to mention that stress dis-
tribution inside the consolidated (i.e. not separated by through-thickness cracks) fragments of the ice
cover is rather homogeneous and correlates mainly with the direction of movement of the fragments them-
selves. At the same time, stress state of neighbo-uring fragments can differ greatly. In accordance with
traditional definition [Zoback,1992], stresses deter-mining deformation processes on the ice cover in-
terplate boundaries can be regarded as "tectonic". Thus, measurement results prove the existence of
"plate tectonics" in the ice cover of Lake Baikal and support its usage for the physical modeling of tec-
tonic processes in the lithosphere being grounded.
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On the basis of measurements of internal plate deformations the threshold stresses of activation of
convergent processes in the underride zones as high-rank deformation-induced structures are esti-
mated. The value of these stresses is connected with inner cohesion on the most solid parts of inter-
plate boundaries and, as a rule, varies within the range 2—10 % of the compression strength of plate
material. In case of "healed" boundaries (after ra-ther long "calm" periods of deformation activity) the
activation threshold value can rise anomalously high (20—30 % of plate material strength). The recent
research results show that high internal stresses can provoke changes of the character of deforma-
tion processes in a block-structured medium, in-cluding the appearance of "precursors" of dynamic
convergent events and effects of fragmentation of consolidated blocks. It gives the ground to the sup-
position that anomalies of deformation regime of the Earth’s crust, registered at various times before large
earthquakes, seem to be connected with reaching a certain threshold level of stress in the area of regi-
stration. Basing on the data obtained on the ice cover we can suppose that a characteristic value of
such strains can reach 20—30 % of rock strength.
It is important to mention that activation of inter-plate boundaries in the ice cover as a multiscale
block-structured medium is preceded by the involve-ment of low-rank deformation mechanisms. As the
seismic monitoring data show, the intensity of their involvement rises abruptly when the activation moment
approaches. Alongside with it, immediately before the activation the number of relatively high-energetic seis-
mic events increases, which reflects growing charac-teristic scale of the involved deformation mechanisms
with the increase in internal stresses.
All said above indicates that both ice cover and the lithosphere are multiscale media with a hierar-
chical system of relaxation mechanisms. Each mechanism corresponds to a typical activation
threshold (stress). Relaxation (and deformation) mechanisms with maximum involvement threshold
are connected with the formation and functioning of interblock boundaries. Thereby, the ice cover of Lake
Baikal gives a unique possibility to study the influ-ence of a strained state on the regularities of defor-
mation accommodation processes in block-struc-tured (plate) media of different nature, particularly, in
the lithosphere.
Hamaguchi H., Goto K. A study on ice faulting and
icequake activity in the Lake Suwa, (2) Temporal
variation of m-value // The Sci. Rep. of the Tohoku
Univer. — 1978. — Ser. 5. 25. — � 1. — P. 25—38.
Psakhie S. G., Dobretsov N. L., Shilko E. V. Model study
of the formation of deformation-induced structures
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cover of Lake Baikal as a model medium // Tec-
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Zoback M. L. First- and second-order patterns of stress
in the lithosphere: The world stress map project //
Geophys. J. Res. — 1992. — 97(B8). — P. 11703—
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