Cohesive strength and seismogenic stress pattern along the active basement faults of the Precordillera-Sierras Pampeanas ranges, western Argentina: An experimental analysis by means of numerical model |
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| Authors: | Md Rafiqul Islam |
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| Institution: | (1) Institute of Geology, China Earthquake Administration, Beijing, 100029, China |
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| Abstract: | A two-dimensional finite element method (FEM) model that incorporates faults, elastic rock physical properties, topographical
load due to gravity and far-field plate velocity boundary conditions was used to recognize the seismogenic stress state along
the fold-and-thrust belt of the Precordillera-Sierras Pampeanas ranges of western Argentina. A plane strain model with nine
experiments was presented here to examine the fault strength with two major rock phyical properties: cohesion and angle of
internal friction. Mohr-Coulomb failure criterion with bulk rock properties were applied to analyse faults. The stress field
at any point of the model was assumed to be comprised of gravitational and tectonic components. The analysis was focused to
recognize the seismogenic shear strain concentrated in the internal-cristaline domain of the orogene shown by the modeling.
Modeling results are presented in terms of four parameters, i. e., (i) distributions, orientations, and magnitudes of principal
stresses (σ1 and σ3), (ii) displacement vector, (iii) strain distribution, and (iv) maximum shear stress (τ
max
) contour line within the model. The simulation results show that the compressive stress is distributed in and around the
fault systems. The overall orientation of σ1 is in horizontal directions, although some stress reorientations do occur within weaker parts, especially subsequent to the
faults. A large-scale shear stress is accumulating along the active faults of Tapias-Villicum Fault (TVF), Salinas-Berros
Fault (SBF), Ampacama-Niquizanga Fault (ANF) and Las Charas Fault (CF), which could act as local stress and strain modulators
to localize the earthquakes occurrence. |
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| Keywords: | Finite element method Rock physical property Fold-and-thrust belt Fault strength Seismogenic shear stress pattern |
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