STRESS FIELD IN A SHEAR ZONE, AND FORMATION OF THE MAIN FAULT
https://doi.org/10.5800/GT-2021-12-3-0536
Abstract
Using the analytical approximation method, we calculated stress field parameters for cases with different relative positions of Riedel shears and loads required for shearing. Considering an internal friction angle of 30°, and the distance between adjacent shears exceeding 0.7 of the characteristic shear length, we estimated the Coulomb stress that can lead to fracturing. In the areas between the shears, it is below the shear strength value. This means that if an increase in the external load is lacking, there are no prerequisites for the formation of new fractures that may connect adjacent shears. If the shears are spaced closer to each other (i.e. at distances less than 0.7 of the shear length), the shear strength is exceeded in the areas between them, and new shears can occur there and connect the Riedel shears to each other. Therefore, in observations of a natural system of Riedel shears, it becomes possible to assess whether this system is sufficiently stable in its current status, or, in case of a critical increase in the Coulomb stress in the areas between adjacent shears, the equilibrium can be easily disturbed, and there is a possibility that the main fault forms in the strike-slip zone under study.
Keywords
Coulomb stress,
shear strength,
second-order structures,
system of subparallel shears,
shear zone,
secondary dislocations
Supporting agencies: The study was carried out under the state assignment of IPE RAS.
About the Author
A. S. Lermontova
Schmidt Institute of Physics of the Earth, Russian Academy of Sciences
Russian Federation
Russian Federation
10-1 Bolshaya Gruzinskaya St, Moscow 123242
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For citations:
Lermontova A.S. STRESS FIELD IN A SHEAR ZONE, AND FORMATION OF THE MAIN FAULT. Geodynamics & Tectonophysics. 2021;12(3):499-507. (In Russ.) https://doi.org/10.5800/GT-2021-12-3-0536
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