Paleostress Analysis in the Northern Birjand, East of Iran: Insights from Inversion of Fault-Slip Data

Ezati, Maryam; Rashidi, Ahmad; Gholami, Ebrahim; Mousavi, Seyed Morteza; Nemati, Majid; Shafieibafti, Shahram; Derakhshani, Reza

doi:10.3390/min12121606

Cited by 11 publications

(7 citation statements)

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“…In this research, to estimate seismic strain rates, we employed two different zoning approaches: 1) For a general investigation based on tectonic zones, we considered occurred earthquakes, information about the tectonics of the study area, mechanisms of the faults, focal mechanisms of the earthquakes, seismic states, fault trends, and geological evidence presented in various studies, e.g., Zagros (Navabpour and Barrier, 2012), Kopeh Dagh (Hollingsworth et al, 2006); Alborz (Rashidi, 2021), Sistan (Ezati et al, 2022b(Ezati et al, , 2023, resulting in fourteen defined tectonic zones. 2) For detailed investigation, we segmented the study area into 336, 1°×…”

Section: Methodsmentioning

confidence: 99%

Quantitative analysis of crustal deformation, seismic strain, and stress estimation in Iran via earthquake mechanisms

Nemati,

Rashidi,

Ezati

et al. 2024

Front. Earth Sci.

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This study investigates the variations in stress, strain, and deformation of the Earth’s crust in Iran arising from tectonic movements and seismic activities. We employed the Kostrov and Molnar methods to quantify these parameters, focusing on the influence of different zoning techniques on the estimations. Analyzing data from 637 earthquakes (moment magnitudes > 5.5) spanning 1909 to 2016, we determined the directions of maximum pressure, tension, and seismic strain through two primary approaches: comprehensive zoning and individual earthquake analysis. Additionally, we assess horizontal shortening and vertical crustal adjustments. Our methodology involves three distinct strategies: individual earthquake analysis, 1° × 1° zoning, and tectonic zoning. The findings demonstrate that the choice of zoning method significantly affects the direction and magnitude of seismic strain estimations. Although both methods identified significant deformations in the Dasht Bayaz and Qaen regions of Eastern Iran, differences between the Kostrov and Molnar methods in estimating seismic strain are observed. The high Zagros region shows signs of crustal thickening, whereas the Zagros foreland exhibits crustal thinning. Intriguingly, Eastern Alborz indicates uplift, and Western Alborz suggests subsidence, offering an alternative view to the conventional tectonic understanding of the Alborz range. These results highlight the critical role of zoning in stress analyses and the disparities between widely used estimation techniques. They underscore the necessity of careful method selection and interpretation in geodynamic studies, particularly in seismically active regions like Iran.

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Section: Methodsmentioning

confidence: 99%

Quantitative analysis of crustal deformation, seismic strain, and stress estimation in Iran via earthquake mechanisms

Nemati,

Rashidi,

Ezati

et al. 2024

Front. Earth Sci.

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“…For a comprehensive tectonic analysis of the study area, a combination of structural and current/paleo-stress is required (Rashidi and Derakhshani, 2022). Therefore, we used stress data from recently published articles by some authors (Jentzer et al, 2017;Ezati et al, 2022b). The Tensor software (Delvaux et al, 1997;Delvaux et al, 2012;Delvaux and Sperner, 2003) was applied to illustrate the structural data, especially for the faults with slickenlines.…”

Section: Methodsmentioning

confidence: 99%

“…In orogenic belts with long deformation history (e.g., East Iran orogen), the general patterns of the deformations (e.g., folds) are related to buckling phases of orogenic belts during various geological times. Here, we used the drastic temporal changes in the stress regimes of East Iran orogenic during the post-late Cretaceous, which have been published by some researchers (Jentzer et al, 2017;Ezati et al, 2022b) 17). Therefore, by changing the stress regime, the characteristics of folds and faults related to the splays (e.g., geometry, mechanism, and strain rates) could have changed several times.…”

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confidence: 99%

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Flexural-slip folding in buckling phases of orogenic belts: Insight into the tectonic evolution of fault splays in the East Iran orogen

et al. 2023

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Introduction: The East Iran orogen has experienced multiple buckling phases resulting in the formation of strike-slip fault splays. The geometric and kinematic characteristics of these splays are influenced by folding mechanisms. This study focuses on investigating the structural characteristics and tectonic evolution model of the Khousf splay, located in the northern terminus of the Nehbandan right-lateral strike-slip fault system.Methods: Field visits and geometrical properties from map views were used to analyze the structural features of the Khousf splay. The splay was found to consist of a multi-plunging anticline and syncline, referred to as the Khousf anticline and Khousf syncline, respectively. Flexural slip was identified as a significant mechanism for the formation of these structures. Structural evidence, including parasitic folds, active folds, and strike-slip duplexes, suggested that flexural slip occurred on discrete movement horizons among the rock units.Results: Analysis of the parasitic folds in the cores and limbs of the Khousf anticline and syncline revealed M, W, Z, and S shapes, with complex slicken-line patterns observed on faults parallel to the beds at the limbs. The analysis results indicated strain partitioning and inclined left- and right-lateral transpressional zones. Shortening estimates obtained from profiles in the Shekarab inclined transpressional zone were approximately 33%, 65%, and 68% for NE-SW, N-S, and NW-SE profiles, respectively. In the Arc area, which is the core of the anticline, shortening estimates from NE-SW and N-S profiles ranged from 14% to 10%. Structural analysis of the folds in this area revealed broad, close, semi-elliptical, and parabolic shapes, suggesting that secondary folds with NW-SE axis directions have been superimposed on the first-generation folds with E-W axis directions in the Khousf refolded splay.Discussion: The findings of this study highlight the structural characteristics and tectonic evolution model of the Khousf splay in the northern terminus of the Nehbandan right-lateral strike-slip fault system. The results suggest that flexural slip played a crucial role in the formation of the multi-plunging anticline and syncline in the Khousf splay. The presence of parasitic folds and complex slicken-line patterns on faults indicate the complexity of deformation processes. The observed strain partitioning and inclined transpressional zones suggest a complex tectonic history in the study area. The superimposition of secondary folds with different axis directions on first-generation folds adds further complexity to the structural evolution of the Khousf refolded splay. Overall, this study provides new insights into the structural characteristics and tectonic evolution of the Khousf splay in the East Iran orogen.

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“…The region with the pink color is the third seismically active area (the area around the Hari Rud fault), in the western of the country, it is influenced by the Arabian fault and transtensional strike-slip faulting along the Iran-Afghanistan border (Austermann & Iaffaldano, 2013;Ezati et al, 2022;Walker & Jackson, 2004) The rest is a seismic calm area mostly covering the Accreted Terrans. The details of the seismic region are explained in the legend on the right side of Figure 7.…”

Section: Earthquake Hazard Map Of Afghanistanmentioning

confidence: 99%

Earthquake Risks and Lack of Disaster Management in Afghanistan

Akhundzadah

2023

Preprint

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Afghanistan is in a seismically active area and is historically hit by destructive earthquakes. It is located on the edge of the Eurasian tectonic plate, bordered by the northern boundary of the Indian plate, and with the collisional Arabian plate into the South. The Hindukush and Pamir Mountains within Afghanistan are the western extension of the Himalayan orogeny uplifted and sheared by Indian and Eurasian plate convergence. These tectonic activities have created several active deep faults across the country and in the Hindukush-Himalayan region, where high-magnitude earthquakes have historically occurred. Earthquakes in Afghanistan are primarily driven by the relative northward movements of the Arabian plate past western Afghanistan and the Indian plate past eastern Afghanistan as both plates subduct under the Eurasian plate. These tectonic movements caused ground shaking from high to moderate and low from the northeast through the southwest of the country. On June 22, 2022, southeastern part of Afghanistan was hit by a destructive Mw6.2 earthquake. The purpose of this study is to develop an ArcGIS Pro database of compiled geologic faults and regions of heightened seismicity for spatial analyses of earthquake disaster severity across Afghanistan. These spatial analyses place better constraints on the placement of active and historic seismicity along mapped and known active faults for progress in earthquake disaster management. Furthermore, we define current hazards associated with building and infrastructural design and competency given the recurrent and eminent seismicity within Afghanistan and describe possible directions and solutions to mitigate the threat to life and property.

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Paleostress Analysis in the Northern Birjand, East of Iran: Insights from Inversion of Fault-Slip Data

Cited by 11 publications

References 54 publications

Quantitative analysis of crustal deformation, seismic strain, and stress estimation in Iran via earthquake mechanisms

Quantitative analysis of crustal deformation, seismic strain, and stress estimation in Iran via earthquake mechanisms

Flexural-slip folding in buckling phases of orogenic belts: Insight into the tectonic evolution of fault splays in the East Iran orogen

Earthquake Risks and Lack of Disaster Management in Afghanistan

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