Tectonics
Hamid Nazari; Jean-Francois Ritz; Ara Avagyan
Abstract
The Alborz mountain range accommodates some of the convergence between Central Iran and Eurasia. At present, the kinematics of the range involves a strain partitioning mechanism, and is associated with clockwise rotation of the South Caspian Basin. left-lateral strike-slip faulting is present along the ...
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The Alborz mountain range accommodates some of the convergence between Central Iran and Eurasia. At present, the kinematics of the range involves a strain partitioning mechanism, and is associated with clockwise rotation of the South Caspian Basin. left-lateral strike-slip faulting is present along the entire of its central part, while reverse faulting is affects its northern and southern borders. Several slip-rate studies have been carried out along active faults in the internal and southern parts of the range. Our analysis provides new constraints on the activity of this important active thrust fault. We show that the fault generally is a hidden thrust fault, often associated with fault-bend and fault-propagation folds (forebergs). In the central part of the fault near Chamestan, radiocarbon dating on an old elevated terrace allows estimating the minimum vertical slip of 2.0± 0.5 mm / year. Considering a 34 degree slope for the fault, the minimum horizontal slip rate will be 3 mm/yr and the minimum slip rate along the fault plane will be up to 3.6 mm / year. Our results confirm that the Khazar Fault is a major active structure in northern Iran, and represents a significant seismic hazard for the entire Central Alborz region.
F. Alahverdi Maygooni; M. Mohamadi Vizheh; A.R. Farrokhnia; E. Boostan; H. Nazari
Abstract
Undoubtedly, one of the evidence of tectonic activity in each region is earthquake, which has a major role in casualties and financial losses. The earthquake is usually caused by faults that sometimes extend to the depths of the earth's crust. In cases where no signs or complications of these faults ...
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Undoubtedly, one of the evidence of tectonic activity in each region is earthquake, which has a major role in casualties and financial losses. The earthquake is usually caused by faults that sometimes extend to the depths of the earth's crust. In cases where no signs or complications of these faults are observed on the surface of the earth, it is necessary to get a better understanding of these faults and its sub branches by combining geological knowledge as well as remote sensing and geophysical instruments. The Kazar fault in the study area is a fundamental fault that has been attributed to at least six historical earthquake events. Due to quaternary activities, recognition of this fault is very important in the region. Therefore, geological and geophysical studies were carried out on the historical site of Gohartepeh in Behshahr city to reveal its hidden parts. Specific resistive methods with bipolar bipolar arrangement at 10 and 20 meters intervals are used to provide sections and maps. By examining them and considering the position and depth of the anomalies obtained in the next stages, new profiles and networks were designed. In order to obtain more accurate results, the cesium magneto metric scanning was performed on 4 profiles. Data obtained from field operations and data acquisition as well as final processing of data in specialized software have been incorporated and clearly interpreted from sub-surface structures, especially faults and discontinuities in the study area, which indicate an impressive anomalous adaptation obtained with field evidence.
