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Hamid NAZARI

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Regards to about three decades scientific and professional background as a geologist in Geological Survey of Iran (GSI) with opportunity for working in many other countries and social activity as critic and socio-political analyst in the Iranian media

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Uppsala University

Gabriel Gutierrez-Alonso

University of Salamanca

Alexander Fantalkin

Tel Aviv University

Prof.Dr. İbrahim USLU

Gazi University

Beverly Goodman

University of Haifa

Kenneth Vecchio

University of California, San Diego

Adam Mickiewicz University in Poznań

Stephen W Merkel

Vrije Universiteit Amsterdam

Colorado State University

Damanhour University

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Papers by Hamid NAZARI

Proposing a New Strategy to Make Precise Re-Leveling Observations of Iran in Vertical Geodynamical Studies

فصلنامه علمی-پژوهشی علوم زمین, Feb 19, 2013

A review to the Desert Kite: State of the Art!

بررسی تحلیلی زمان احتمال رخداد زمینلرزه درگستره تهران: مروری بر پژوهشهای پارینهلرزهشناسی

فصلنامه علمی-پژوهشی علوم زمین, Feb 20, 2015

Analysis of Strike-Slip Kinematics in a Shear Zone with Heterogeneous Slip Rate: Case Study Lutarea, Eastern Iran

فصلنامه علمی-پژوهشی علوم زمین, Dec 1, 2016

Astara断層系,イラン北部上の滑り速度の評価【Powered by NICT】

نقش ساختارهای تراکششی در جایگیری پهنههای سیلیسی طلادار در جنوب باختر سبلان، شمال باختر ایران

فلات آذربایجان دارای تنوع ریخت‌شناسی و انواع کانی‌سازی‌هاست که هر دو آنها تحت تأثیر رژیم ساختاری ... more فلات آذربایجان دارای تنوع ریخت‌شناسی و انواع کانی‌سازی‌هاست که هر دو آنها تحت تأثیر رژیم ساختاری حاکم بر منطقه هستند. این رژیم از زمان برخورد صفحه عربی با اورازیا شروع شده و تا زمان حاضر ادامه دارد. گسل‌های راستا‌لغز مهم‌ترین عامل تغییرات ساختاری و شکل‎دهنده پهنه‌های مختلف کششی و فشارشی و مظاهر مختلف این پهنه‌ها در آذربایجان هستند. گسل‌های چیره دارای روند شمال باختری- جنوب خاوری و بیشتر دارای سازکار راستالغز راست‌بر هستند؛ در حالی‌که گسل‌های دیگر با روند شمال خاوری- جنوب باختری بیشتر سازوکار چپ‌بر دارند. وضعیت بردار حرکتی در دو سوی گسل‌ها، در محل برخورد، تعیین کننده رژیم زمین‌ساختی حاکم است و در نتیجه ریخت‌شناسی، نفوذ دایک‌هاو رگه‌ها را تحت کنترل دارند. محل خمش گسل‌های راستا‌لغز و محل پیوستن قطعات مختلف یک گسل نیز از مناطقی هستند که رژیم زمین‌ساختی حاکم بر آنها سبب جایگیری استوک‌های نفوذی گرانیتی مستعد برای کانی‌سازی ویا شکل‎گیری رگه‌های متعدد سیلیسی طلادار شده است. در منطقه جنوب باختری سبلان به دلیل خمش در راستای گسل اهر- سراب، رژیم زمین‌ساختی کششی حاکم و منجر به نفوذ رگه‌های متعدد...

اولین نشانه های زمین لرزه تاریخی 1384 AD شهرری، بر روی گسل پیشوا بر پایه پژوهش های پارینهلرزه شناختی، جنوبخاوری تهران

گسل پیشوا با درازای حدود 35 کیلومتر در جنوب‌خاوری ورامین قرار گرفته است. این گسل در جنوبیترین مر... more گسل پیشوا با درازای حدود 35 کیلومتر در جنوب‌خاوری ورامین قرار گرفته است. این گسل در جنوبیترین مرز میان ایالتهای ساختاری البرز و ایران مرکزی واقع شده و روند کلی آن شمال‌باختری– جنوب‌خاوری (N38W, 33NE) و دارای سازوکار وارون با مؤلفه چپبر همراه با گسلهای ناهمسوی (Antithetic) عادی است. بررسی‌های ریخت‌زمین‌ساختی انجام شده در راستای گسل پیشوا، نشان از فعال بودن آن دارد. بر پایه بررسیهای انجام شده در ساختگاههای T1 و T2 ترانشه پارینه لرزه‌شناسی گسل پیشوا، تعداد 3 تا 5 رخداد لرزهای با دوره بازگشت 3265 سال برای این گسل شناسایی شد که جوان‌ترین و کهنترین رخدادها به‌ترتیب سن87/0 ، 29 هزار سالدارند. برپایه میزان جابه‌جایی در مدت هر رویداد مه لرزهای و با بهرهگیری از روابط Wells & Coppersmith (1994) بزرگ‌ترین و کوچک‌ترین زمین‌لرزه شناسایی شده به‌ترتیب دارای بزرگای 08/7 و 9/5 هستند. از آن جاییکه سن جوان‌ترین رویداد شناسایی شده در حدود 870 سال به دست آمد، بنابراین احتمالا بتوان زمینلرزهAD 1384 (میلادی)شهرری را به این گسل منتسب دانست.

Modeling the sources of the Azgeleh (12 November 2017) and Tazehabad (25 August 2018) earthquakes, Western Iran

EGU General Assembly Conference Abstracts, Apr 1, 2019

Irregular recurrence of surface-faulting paleoearthquakes along the Gowk fault, southeast Iran

While long-averaged recurrence times of large earthquakes are documented on many slow-slipping fa... more While long-averaged recurrence times of large earthquakes are documented on many slow-slipping fault zones in intracontinental settings, the variability of the return periods through multiple seismic cycles remains poorly known. Paleoseismic investigations across fault zones with the well-documented instrumental sequence of surface-breaking earthquakes are a way to tackle the problem. In this context, the Gowk fault, a 160-km-long dextral fault in central Iran, that experienced four surface-rupturing earthquakes with magnitudes ranging from Mw 5.8 to 7.0 during a 1981-1998 earthquake sequence offers a case study. The four earthquakes have ruptured a 90-km-stretch of the fault. The most recent one, the 14 March 1998 Fandoqa earthquake of Mw 6.6, produced a 23-km-long surface rupture along the northern part of the Gowk fault with a maximum right-lateral displacement of 3 m. With a Holocene slip-rate between 3.8-5.7 mm yr-1 and several recent seismic events testifying to its high level of seismicity, the Gowk fault is an appropriate target to conduct paleoseismic investigations and address the earthquake behavior of slow-slipping faults activated by a sequence of well-documented instrumental earthquakes. We excavated two neighboring trenches across the 1998 fault breaks and identified at least four Holocene event horizons that preceded the 1981-1998 earthquake sequence. The age of the faulted stratigraphic sequence is constrained by eighteen optically stimulated luminescence samples and one radiocarbon age on charcoal. The ages of the event horizons suggest an irregular seismic behavior of the Gowk fault characterized by significant variability in the return period of surface rupturing earthquakes.

Morphotectonics and Slip rate of the Khazar fault in Central Alborz, (North of Iran)

فصلنامه علمی علوم زمین, Aug 23, 2021

The Alborz mountain range accommodates some of the convergence between Central Iran and Eurasia. ... more 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.

Detection of fault segments based on P–T dihedra analysis along the North Tabriz fault, NW Iran

Iranian Journal of Earth Sciences, Oct 1, 2020

Detection of fault segments is an essential step for tracking main transverse faults. General obs... more Detection of fault segments is an essential step for tracking main transverse faults. General observations from field studies as well as attitude measurements can give an overall understanding of the lengths of the segments, but these are not always sufficient to accurately identify and characterize them. In this study, we analyze P-T dihedra variations based on their eigenvalues to detect fault segments. The anomalies of local paleostress distribution aid us to detect the segment boundaries. This study focuses on the Northwestern, Central, and Southeastern sectors of the North Tabriz Fault (NTF). Fault azimuth distribution and eigenvalue anomalies as well as the fault attitudes for each interval distance have been used to distinct segment boundaries. The results are verified by checking the presence of the transverse faults at the proposed sites during fieldwork. Results show a new structural arrangement integrated by the already documented NTF segments, combined with 6 related transverse faults. In this way, we confirm the earlier reported segments, and we improve the NFT characterization by introducing new segments bounded by transverse faults.

$Fig 10. a) Difference in the dip direction of the Miocene sequences on both sides of the transverse fault (red triangles) in the Tabriz Telecabin site (station 1). b) Shear fractures on the mentioned transverse fault (Einali fault) plane. c) The Angelier diagram showing the orientation of fault planes (circles) and striae on fault surfaces (arrows)$

Kinematics of a sigmoidal fold and vertical axis rotation in the east of the Zagros–Makran syntaxis (southern Iran): Paleomagnetic, magnetic fabric and microtectonic approaches

Tectonophysics, Dec 1, 2005

The Zagros Simple Fold Belt is characterized by elongated, curved, or sigmoidal folds. The trend ... more The Zagros Simple Fold Belt is characterized by elongated, curved, or sigmoidal folds. The trend of these structures together with the structural style, change suddenly across the Zagros-Makran syntaxis which separates the continental collision domain of Zagros from the oceanic subduction one in Makran. This work focuses on the Minab anticline, outcropping in the easternmost part of Zagros. In order to understand the kinematics of a sigmoidal fold and underscore possible vertical axis rotations in the eastern side of the syntaxis, we performed a joint study of magnetic fabric, microtectonics and paleomagnetism of the northern termination of this fold. The two limbs have been sampled (7 sites, 134 samples) along three cross-sections corresponding to three different orientations of the fold axis. The rocks are weakly deformed fine-grained Mio-Pliocene reddish siltstones. The shortening directions deduced from both magnetic fabric analysis and microtectonic observations are consistent with each other, they are horizontal and roughly perpendicular to the local fold axis, following the torsion of the fold hinge line, and indicating a tectonic origin of the magnetic fabric. Rockmagnetic analyses (thermomagnetic curves, hysteresis loops) point to the presence of magnetite in the PSD and MD ranges as the main magnetic carriers, together with a minor contribution from hematite. Apart from a post-tilting sub-actual VRM and/or CRM (component A), paleomagnetic analyses yield mainly two pre-tilting magnetization components: Component B is carried by magnetite, spanning the intermediate to high unblocking temperature range (300 8C V T ubs V 580 8C). Component C has unblocking temperatures characteristic of hematite (580 8C V T ubs V 680 8C). Both are ante-folding, based on positive reversal and fold tests, inside each of the cross-section but also for the three sections together. However, because component C is biased by some inclination flattening, only component B is taken into account afterwards. After full tectonic correction, the site mean direction of component B calculated for 6 out of the 7 sites is not statistically different from the individual site mean directions. The intersection direction determined by small circle analysis in these six sites is: D = 18.08 I = 33.78 k = 482 alpha 95 = 2.68. Compared to the Mio-Pliocene direction expected in this area for Africa, it corresponds to an overall clockwise rotation of the whole structure of some 18.38 F 5.18, consistent with the regional geodynamic context.

Extrusion tectonics and subduction in the eastern South Caspian region since 10 Ma: REPLY

Geology, Dec 1, 2009

Hollingsworth et al. (2008) proposed a "new" kinematic model for the complicated tectonic pattern... more Hollingsworth et al. (2008) proposed a "new" kinematic model for the complicated tectonic pattern in the eastern South Caspian Sea region. Our Comment is focused on the Ashkhabad fault and the Kopeh Dagh Mountains, examining the data and hypothesis used by the authors to support their model. Hollingsworth et al. presented 10 m of right-lateral displacement along the Ashkhabad fault, recorded by a river bank and a line of irrigation system. In this area, the well-expressed fault trace (Fig. 1A) is not consistent with that proposed by the authors (their fi gure 2B). Moreover, there is no clear evidence of right-lateral displacements where the fault traces intersect either other river banks or erosional gullies (Fig. 1A). Accepting the particular line of irrigation as representative for rightlateral fault offset, it should be noted that the offset is on the order of 14 m, and not 10 m. Irrigation lines can be right-laterally or left-laterally

Analyse de la tectonique récente et active dans l'Alborz Central et la région de Téhéran : « Approche morphotectonique et paléoseismologique »

The tectonic activity in the Alborz mountain range, northern Iran, is due both to the northward c... more The tectonic activity in the Alborz mountain range, northern Iran, is due both to the northward convergence of central Iran toward Eurasia, and to the northwestward motion of the South Caspian Basin with respect to Eurasia inducing a left-lateral wrenching along this range. These two mechanisms give rise to a NNE-SSW transpressional regime, which is believed to have affected the entire range for the last 5 ؎ 2 m.y. In this paper, we show that the internal domain of central Alborz is not affected by a transpressional regime but by an active transtension with a WNW-ESE extensional axis. We show that this transtension is young (middle Pleistocene). It postdates an earlier N-S compression and may have been initiated when the South Caspian Basin started moving. Consequently, our results suggest that the South Caspian Basin motion may have taken place more recently than previously proposed.

Quaternary coral-reef terraces from Kish and Qeshm Islands, Persian Gulf: new radiometric ages and tectonic implications

Quaternary International, 2004

A survey of raised coral reef terraces in locations along the southern coast of Iran was carried ... more A survey of raised coral reef terraces in locations along the southern coast of Iran was carried out with the aim of assessing regional Late Quaternary tectonic uplift rates influenced by salt doming. Two islands were studied: Kish, where no previous data were available, and Qeshm, where a previous survey had already attributed the lowest step in two sequences of raised marine terraces to the Last Interglacial. Twenty-five ESR and seven Th/U ages were obtained from Kish Island. The results show that this flat, about 32 m high, gently domed island was totally submerged during the last two interglacial periods. Corals ascribed to MIS 5 and MIS 7 have been dated at the same elevations, near the present sea level, and in the uppermost, inner part of the island, giving evidence of a polycyclic origin for the island surface deposits. Following a discussion on the possible position of eustatic peaks during MIS 7, a maximal average uplift rate of 0.2070.02 mm/yr has been deduced from the above data. Furthermore, the survey obtained some new results from Qeshm, where seven ESR ages confirmed the MIS 5 age of the lowest raised marine terrace (that also corresponds to an uplift rate of about 0.2 mm/yr), failing, however, to date older steps, due to significant coral-sample re-crystallisation. In the western part of Qeshm, five new radiocarbon ages of elevated beach material demonstrated the variability of uplift rates even along short distances around an active salt dome.

Micro biostratigraphy and paleo environment of Oligo-Miocene deposits in north of central Iran

فصلنامه علمی علوم زمین, May 22, 2021

Oligo-Miocene rocks are deposited between Pyrenean and Pasadenian orogenic phases. This rocks in ... more Oligo-Miocene rocks are deposited between Pyrenean and Pasadenian orogenic phases. This rocks in central Iran back arc deposits are named Qom formation. There are well developed outcrops of Qom formation at the North of Central Iran zone. In order to study microbiostratigraphy of the formation, Three sections, north west of Darjazin town , Bonak mount and Arvaneh were selected. In these sections Qom formation with discontinuity overlays the Lower Red formation and with the same quality under the Late Miocene Conglomerate with intercalations of Sandstone, which is equivalent to the Upper Red Formation is placed. The main lithological composition of the Qom Formation in the study area alternates between layers of limestone and Marl with intercalations of siliciclastic rocks. Members and submembers of the Qom formation type area are not visible in this area and can only based on the lithological characteristics divide to local units. Based on bentic foraminifera and other microbiostratigraphical data, Qom Formation age in north west-west of Semnan (Darjazin-After zone), which is located in the Central Alborz structural-sedimentary zone, is early Miocene epoch and Burdigalian stage, which is the equivalent of Borelis melo curdica-Borelis melo biozone.

Future stress accumulation zones around the main active faults by 3D numerical simulation in East Azerbaijan Province, Iran

Acta geodaetica et geophysica, Nov 13, 2019

As a preliminary three-dimensional numerical analysis, this research aims to detect future zones ... more As a preliminary three-dimensional numerical analysis, this research aims to detect future zones of high-stress accumulation caused by the interaction of active faults within a 3D topographic geological block based on finite-element analysis. Stress analysis of the threedimensional topographic model covers both static and dynamic loading caused by topographic loads and crustal movements, and can provide more realistic results. There are many applications to create topographic models from xyz data. Nevertheless, these models do not have the properties required in analytical software. Solid meshing of topographic blocks is abstruse and consumes much time and high CPU usage. Therefore, we first try to create a validated topographic shell model through the introduced methods including nodal projection and statistical analysis, and then upgrade it to a solid model. The stress equations are then assigned to each element of the solid model. The outputs include stress accumulation zones in both pre-failure and failure mode for the whole model. In addition, energy diagrams show the rate of main energies per time and accordingly, represent the perception of power for each energy output. Energy drop during the initial run time is consistent with the collision of the blocks of the model.

Evaluation of slip rate on Astara fault system, North Iran

Journal of Earth Science, Dec 1, 2016

Due to its strategic location, the Astara fault system (AFS), which is located in Iran, has given... more Due to its strategic location, the Astara fault system (AFS), which is located in Iran, has given rise to a number of earthquakes. In spite of its frequent seismic events, limited information is available for AFS. Slip rate is one of the important variables for future scrutiny of seismic risk of this fault system. The main objective of this research is to study slip rates at intermediate and short terms for this fault system using geological, geodetic observations and empirical method. Using the geological data, the intermediate-term horizontal and vertical slip rates for AFS have been determined to be 2.8±0.2 and 0.27±0.03 mm/year, respectively. In addition, the short-term slip rates of the fault, based on the geodetic method (using displacement values of two GPS stations: HASH and DAMO) and assuming attenuation of 60% (to fold the sediment of South Caspian Basin and shortening of Talesh Mountain range), determined to be 1.23±0.03 and 2.05±0.05 mm/year for the horizontal and vertical slips, respectively. Finally, evaluation of the slip rate using empirical relationship yields 10 mm/year for the entire fault system, which seems rather implausible.

Seismotectonic, rupture process, and earthquake-hazard aspects of the 2003 December 26 Bam, Iran, earthquake

Geophysical Journal International, Sep 1, 2006

The catastrophic 2003 M w 6.6 Bam earthquake in southern Iran attracted much attention, and has b... more The catastrophic 2003 M w 6.6 Bam earthquake in southern Iran attracted much attention, and has been studied with an abundance of observations from synthetic aperture radar, teleseismic seismology, aftershock studies, strong ground motion, geomorphology, remote sensing and surface field work. Many reports have focused on the details of one or other data type, producing interpretations that either conflict with other data or leave questions unanswered. This paper is an attempt to look at all the available data types together, to produce a coherent picture of the coseismic faulting in 2003 and to examine its consequences for active tectonics and continuing seismic hazard in the region. We conclude that more than 80 per cent of the moment release in the main shock occurred on a near-vertical right-lateral strike-slip fault extending from the city of Bam southwards for about 15 km, with slip of up to 2 m but mostly restricted to the depth range 2-7 km. Analysis of the strong ground motion record at Bam is consistent with this view, and indicates that the extreme damage in the city can be attributed, at least in part, to the enhancement of ground motion in Bam because of its position at the end of the northward-propagating rupture. Little of the slip in the main shock reached the Earth's surface and, more importantly, aftershocks reveal that ∼12 km vertical extent of a deeper part of the fault system remained unruptured beneath the coseismic rupture plane, at depths of 8-20 km. This may represent a substantial remaining seismic hazard to the reconstructed city of Bam. We believe that some oblique-reverse slip (up to 2 m, and less than 20 per cent of the released seismic moment) occurred at a restricted depth of 5-7 km on a blind west-dipping fault that projects to the surface at the Bam-Baravat escarpment, an asymmetric anticline ridge that is the most prominent geomorphological feature in the area. This fault did not rupture significantly at shallow levels in 2003, and it may also represent a continuing seismic hazard. Widespread distributed surface ruptures north of the city are apparently unrelated to substantial slip at depth, and may be the result of enhanced ground motion related to northward propagation of the rupture. The faulting at Bam may be in the early stages of a spatial separation ('partitioning') between the reverse and strike-slip components of an oblique convergence across the zone. Such a separation is common on the continents, though in this case the slip vectors between the two faults differ only by ∼20 • as a substantial strike-slip component remains on the obliquereverse fault. The Bam earthquake is one in a series of large earthquakes involving faulting along the western edge of the Lut desert. In addition to the unruptured parts of the faults near Bam itself, continuing and substantial hazard is represented by unruptured neighbouring faults, particularly blind thrusts along the Jebel Barez mountains to the south and strike-slip faulting at Sarvestan to the west.

Neotectonics and paleoseismology of the North Tabriz Fault, Azerbaijan Region, Northwest Iran

Journal of Asian Earth Sciences

Proposing a New Strategy to Make Precise Re-Leveling Observations of Iran in Vertical Geodynamical Studies

فصلنامه علمی-پژوهشی علوم زمین, Feb 19, 2013

A review to the Desert Kite: State of the Art!

بررسی تحلیلی زمان احتمال رخداد زمینلرزه درگستره تهران: مروری بر پژوهشهای پارینهلرزهشناسی

فصلنامه علمی-پژوهشی علوم زمین, Feb 20, 2015

Analysis of Strike-Slip Kinematics in a Shear Zone with Heterogeneous Slip Rate: Case Study Lutarea, Eastern Iran

فصلنامه علمی-پژوهشی علوم زمین, Dec 1, 2016

Astara断層系,イラン北部上の滑り速度の評価【Powered by NICT】

نقش ساختارهای تراکششی در جایگیری پهنههای سیلیسی طلادار در جنوب باختر سبلان، شمال باختر ایران

فلات آذربایجان دارای تنوع ریخت‌شناسی و انواع کانی‌سازی‌هاست که هر دو آنها تحت تأثیر رژیم ساختاری ... more فلات آذربایجان دارای تنوع ریخت‌شناسی و انواع کانی‌سازی‌هاست که هر دو آنها تحت تأثیر رژیم ساختاری حاکم بر منطقه هستند. این رژیم از زمان برخورد صفحه عربی با اورازیا شروع شده و تا زمان حاضر ادامه دارد. گسل‌های راستا‌لغز مهم‌ترین عامل تغییرات ساختاری و شکل‎دهنده پهنه‌های مختلف کششی و فشارشی و مظاهر مختلف این پهنه‌ها در آذربایجان هستند. گسل‌های چیره دارای روند شمال باختری- جنوب خاوری و بیشتر دارای سازکار راستالغز راست‌بر هستند؛ در حالی‌که گسل‌های دیگر با روند شمال خاوری- جنوب باختری بیشتر سازوکار چپ‌بر دارند. وضعیت بردار حرکتی در دو سوی گسل‌ها، در محل برخورد، تعیین کننده رژیم زمین‌ساختی حاکم است و در نتیجه ریخت‌شناسی، نفوذ دایک‌هاو رگه‌ها را تحت کنترل دارند. محل خمش گسل‌های راستا‌لغز و محل پیوستن قطعات مختلف یک گسل نیز از مناطقی هستند که رژیم زمین‌ساختی حاکم بر آنها سبب جایگیری استوک‌های نفوذی گرانیتی مستعد برای کانی‌سازی ویا شکل‎گیری رگه‌های متعدد سیلیسی طلادار شده است. در منطقه جنوب باختری سبلان به دلیل خمش در راستای گسل اهر- سراب، رژیم زمین‌ساختی کششی حاکم و منجر به نفوذ رگه‌های متعدد...

اولین نشانه های زمین لرزه تاریخی 1384 AD شهرری، بر روی گسل پیشوا بر پایه پژوهش های پارینهلرزه شناختی، جنوبخاوری تهران

گسل پیشوا با درازای حدود 35 کیلومتر در جنوب‌خاوری ورامین قرار گرفته است. این گسل در جنوبیترین مر... more گسل پیشوا با درازای حدود 35 کیلومتر در جنوب‌خاوری ورامین قرار گرفته است. این گسل در جنوبیترین مرز میان ایالتهای ساختاری البرز و ایران مرکزی واقع شده و روند کلی آن شمال‌باختری– جنوب‌خاوری (N38W, 33NE) و دارای سازوکار وارون با مؤلفه چپبر همراه با گسلهای ناهمسوی (Antithetic) عادی است. بررسی‌های ریخت‌زمین‌ساختی انجام شده در راستای گسل پیشوا، نشان از فعال بودن آن دارد. بر پایه بررسیهای انجام شده در ساختگاههای T1 و T2 ترانشه پارینه لرزه‌شناسی گسل پیشوا، تعداد 3 تا 5 رخداد لرزهای با دوره بازگشت 3265 سال برای این گسل شناسایی شد که جوان‌ترین و کهنترین رخدادها به‌ترتیب سن87/0 ، 29 هزار سالدارند. برپایه میزان جابه‌جایی در مدت هر رویداد مه لرزهای و با بهرهگیری از روابط Wells & Coppersmith (1994) بزرگ‌ترین و کوچک‌ترین زمین‌لرزه شناسایی شده به‌ترتیب دارای بزرگای 08/7 و 9/5 هستند. از آن جاییکه سن جوان‌ترین رویداد شناسایی شده در حدود 870 سال به دست آمد، بنابراین احتمالا بتوان زمینلرزهAD 1384 (میلادی)شهرری را به این گسل منتسب دانست.

Modeling the sources of the Azgeleh (12 November 2017) and Tazehabad (25 August 2018) earthquakes, Western Iran

EGU General Assembly Conference Abstracts, Apr 1, 2019

Irregular recurrence of surface-faulting paleoearthquakes along the Gowk fault, southeast Iran

While long-averaged recurrence times of large earthquakes are documented on many slow-slipping fa... more While long-averaged recurrence times of large earthquakes are documented on many slow-slipping fault zones in intracontinental settings, the variability of the return periods through multiple seismic cycles remains poorly known. Paleoseismic investigations across fault zones with the well-documented instrumental sequence of surface-breaking earthquakes are a way to tackle the problem. In this context, the Gowk fault, a 160-km-long dextral fault in central Iran, that experienced four surface-rupturing earthquakes with magnitudes ranging from Mw 5.8 to 7.0 during a 1981-1998 earthquake sequence offers a case study. The four earthquakes have ruptured a 90-km-stretch of the fault. The most recent one, the 14 March 1998 Fandoqa earthquake of Mw 6.6, produced a 23-km-long surface rupture along the northern part of the Gowk fault with a maximum right-lateral displacement of 3 m. With a Holocene slip-rate between 3.8-5.7 mm yr-1 and several recent seismic events testifying to its high level of seismicity, the Gowk fault is an appropriate target to conduct paleoseismic investigations and address the earthquake behavior of slow-slipping faults activated by a sequence of well-documented instrumental earthquakes. We excavated two neighboring trenches across the 1998 fault breaks and identified at least four Holocene event horizons that preceded the 1981-1998 earthquake sequence. The age of the faulted stratigraphic sequence is constrained by eighteen optically stimulated luminescence samples and one radiocarbon age on charcoal. The ages of the event horizons suggest an irregular seismic behavior of the Gowk fault characterized by significant variability in the return period of surface rupturing earthquakes.

Morphotectonics and Slip rate of the Khazar fault in Central Alborz, (North of Iran)

فصلنامه علمی علوم زمین, Aug 23, 2021

The Alborz mountain range accommodates some of the convergence between Central Iran and Eurasia. ... more 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.

Detection of fault segments based on P–T dihedra analysis along the North Tabriz fault, NW Iran

Iranian Journal of Earth Sciences, Oct 1, 2020

Detection of fault segments is an essential step for tracking main transverse faults. General obs... more Detection of fault segments is an essential step for tracking main transverse faults. General observations from field studies as well as attitude measurements can give an overall understanding of the lengths of the segments, but these are not always sufficient to accurately identify and characterize them. In this study, we analyze P-T dihedra variations based on their eigenvalues to detect fault segments. The anomalies of local paleostress distribution aid us to detect the segment boundaries. This study focuses on the Northwestern, Central, and Southeastern sectors of the North Tabriz Fault (NTF). Fault azimuth distribution and eigenvalue anomalies as well as the fault attitudes for each interval distance have been used to distinct segment boundaries. The results are verified by checking the presence of the transverse faults at the proposed sites during fieldwork. Results show a new structural arrangement integrated by the already documented NTF segments, combined with 6 related transverse faults. In this way, we confirm the earlier reported segments, and we improve the NFT characterization by introducing new segments bounded by transverse faults.

$Fig 10. a) Difference in the dip direction of the Miocene sequences on both sides of the transverse fault (red triangles) in the Tabriz Telecabin site (station 1). b) Shear fractures on the mentioned transverse fault (Einali fault) plane. c) The Angelier diagram showing the orientation of fault planes (circles) and striae on fault surfaces (arrows)$

Kinematics of a sigmoidal fold and vertical axis rotation in the east of the Zagros–Makran syntaxis (southern Iran): Paleomagnetic, magnetic fabric and microtectonic approaches

Tectonophysics, Dec 1, 2005

The Zagros Simple Fold Belt is characterized by elongated, curved, or sigmoidal folds. The trend ... more The Zagros Simple Fold Belt is characterized by elongated, curved, or sigmoidal folds. The trend of these structures together with the structural style, change suddenly across the Zagros-Makran syntaxis which separates the continental collision domain of Zagros from the oceanic subduction one in Makran. This work focuses on the Minab anticline, outcropping in the easternmost part of Zagros. In order to understand the kinematics of a sigmoidal fold and underscore possible vertical axis rotations in the eastern side of the syntaxis, we performed a joint study of magnetic fabric, microtectonics and paleomagnetism of the northern termination of this fold. The two limbs have been sampled (7 sites, 134 samples) along three cross-sections corresponding to three different orientations of the fold axis. The rocks are weakly deformed fine-grained Mio-Pliocene reddish siltstones. The shortening directions deduced from both magnetic fabric analysis and microtectonic observations are consistent with each other, they are horizontal and roughly perpendicular to the local fold axis, following the torsion of the fold hinge line, and indicating a tectonic origin of the magnetic fabric. Rockmagnetic analyses (thermomagnetic curves, hysteresis loops) point to the presence of magnetite in the PSD and MD ranges as the main magnetic carriers, together with a minor contribution from hematite. Apart from a post-tilting sub-actual VRM and/or CRM (component A), paleomagnetic analyses yield mainly two pre-tilting magnetization components: Component B is carried by magnetite, spanning the intermediate to high unblocking temperature range (300 8C V T ubs V 580 8C). Component C has unblocking temperatures characteristic of hematite (580 8C V T ubs V 680 8C). Both are ante-folding, based on positive reversal and fold tests, inside each of the cross-section but also for the three sections together. However, because component C is biased by some inclination flattening, only component B is taken into account afterwards. After full tectonic correction, the site mean direction of component B calculated for 6 out of the 7 sites is not statistically different from the individual site mean directions. The intersection direction determined by small circle analysis in these six sites is: D = 18.08 I = 33.78 k = 482 alpha 95 = 2.68. Compared to the Mio-Pliocene direction expected in this area for Africa, it corresponds to an overall clockwise rotation of the whole structure of some 18.38 F 5.18, consistent with the regional geodynamic context.

Extrusion tectonics and subduction in the eastern South Caspian region since 10 Ma: REPLY

Geology, Dec 1, 2009

Hollingsworth et al. (2008) proposed a "new" kinematic model for the complicated tectonic pattern... more Hollingsworth et al. (2008) proposed a "new" kinematic model for the complicated tectonic pattern in the eastern South Caspian Sea region. Our Comment is focused on the Ashkhabad fault and the Kopeh Dagh Mountains, examining the data and hypothesis used by the authors to support their model. Hollingsworth et al. presented 10 m of right-lateral displacement along the Ashkhabad fault, recorded by a river bank and a line of irrigation system. In this area, the well-expressed fault trace (Fig. 1A) is not consistent with that proposed by the authors (their fi gure 2B). Moreover, there is no clear evidence of right-lateral displacements where the fault traces intersect either other river banks or erosional gullies (Fig. 1A). Accepting the particular line of irrigation as representative for rightlateral fault offset, it should be noted that the offset is on the order of 14 m, and not 10 m. Irrigation lines can be right-laterally or left-laterally

Analyse de la tectonique récente et active dans l'Alborz Central et la région de Téhéran : « Approche morphotectonique et paléoseismologique »

The tectonic activity in the Alborz mountain range, northern Iran, is due both to the northward c... more The tectonic activity in the Alborz mountain range, northern Iran, is due both to the northward convergence of central Iran toward Eurasia, and to the northwestward motion of the South Caspian Basin with respect to Eurasia inducing a left-lateral wrenching along this range. These two mechanisms give rise to a NNE-SSW transpressional regime, which is believed to have affected the entire range for the last 5 ؎ 2 m.y. In this paper, we show that the internal domain of central Alborz is not affected by a transpressional regime but by an active transtension with a WNW-ESE extensional axis. We show that this transtension is young (middle Pleistocene). It postdates an earlier N-S compression and may have been initiated when the South Caspian Basin started moving. Consequently, our results suggest that the South Caspian Basin motion may have taken place more recently than previously proposed.

Quaternary coral-reef terraces from Kish and Qeshm Islands, Persian Gulf: new radiometric ages and tectonic implications

Quaternary International, 2004

A survey of raised coral reef terraces in locations along the southern coast of Iran was carried ... more A survey of raised coral reef terraces in locations along the southern coast of Iran was carried out with the aim of assessing regional Late Quaternary tectonic uplift rates influenced by salt doming. Two islands were studied: Kish, where no previous data were available, and Qeshm, where a previous survey had already attributed the lowest step in two sequences of raised marine terraces to the Last Interglacial. Twenty-five ESR and seven Th/U ages were obtained from Kish Island. The results show that this flat, about 32 m high, gently domed island was totally submerged during the last two interglacial periods. Corals ascribed to MIS 5 and MIS 7 have been dated at the same elevations, near the present sea level, and in the uppermost, inner part of the island, giving evidence of a polycyclic origin for the island surface deposits. Following a discussion on the possible position of eustatic peaks during MIS 7, a maximal average uplift rate of 0.2070.02 mm/yr has been deduced from the above data. Furthermore, the survey obtained some new results from Qeshm, where seven ESR ages confirmed the MIS 5 age of the lowest raised marine terrace (that also corresponds to an uplift rate of about 0.2 mm/yr), failing, however, to date older steps, due to significant coral-sample re-crystallisation. In the western part of Qeshm, five new radiocarbon ages of elevated beach material demonstrated the variability of uplift rates even along short distances around an active salt dome.

Micro biostratigraphy and paleo environment of Oligo-Miocene deposits in north of central Iran

فصلنامه علمی علوم زمین, May 22, 2021

Oligo-Miocene rocks are deposited between Pyrenean and Pasadenian orogenic phases. This rocks in ... more Oligo-Miocene rocks are deposited between Pyrenean and Pasadenian orogenic phases. This rocks in central Iran back arc deposits are named Qom formation. There are well developed outcrops of Qom formation at the North of Central Iran zone. In order to study microbiostratigraphy of the formation, Three sections, north west of Darjazin town , Bonak mount and Arvaneh were selected. In these sections Qom formation with discontinuity overlays the Lower Red formation and with the same quality under the Late Miocene Conglomerate with intercalations of Sandstone, which is equivalent to the Upper Red Formation is placed. The main lithological composition of the Qom Formation in the study area alternates between layers of limestone and Marl with intercalations of siliciclastic rocks. Members and submembers of the Qom formation type area are not visible in this area and can only based on the lithological characteristics divide to local units. Based on bentic foraminifera and other microbiostratigraphical data, Qom Formation age in north west-west of Semnan (Darjazin-After zone), which is located in the Central Alborz structural-sedimentary zone, is early Miocene epoch and Burdigalian stage, which is the equivalent of Borelis melo curdica-Borelis melo biozone.

Future stress accumulation zones around the main active faults by 3D numerical simulation in East Azerbaijan Province, Iran

Acta geodaetica et geophysica, Nov 13, 2019

As a preliminary three-dimensional numerical analysis, this research aims to detect future zones ... more As a preliminary three-dimensional numerical analysis, this research aims to detect future zones of high-stress accumulation caused by the interaction of active faults within a 3D topographic geological block based on finite-element analysis. Stress analysis of the threedimensional topographic model covers both static and dynamic loading caused by topographic loads and crustal movements, and can provide more realistic results. There are many applications to create topographic models from xyz data. Nevertheless, these models do not have the properties required in analytical software. Solid meshing of topographic blocks is abstruse and consumes much time and high CPU usage. Therefore, we first try to create a validated topographic shell model through the introduced methods including nodal projection and statistical analysis, and then upgrade it to a solid model. The stress equations are then assigned to each element of the solid model. The outputs include stress accumulation zones in both pre-failure and failure mode for the whole model. In addition, energy diagrams show the rate of main energies per time and accordingly, represent the perception of power for each energy output. Energy drop during the initial run time is consistent with the collision of the blocks of the model.

Evaluation of slip rate on Astara fault system, North Iran

Journal of Earth Science, Dec 1, 2016

Due to its strategic location, the Astara fault system (AFS), which is located in Iran, has given... more Due to its strategic location, the Astara fault system (AFS), which is located in Iran, has given rise to a number of earthquakes. In spite of its frequent seismic events, limited information is available for AFS. Slip rate is one of the important variables for future scrutiny of seismic risk of this fault system. The main objective of this research is to study slip rates at intermediate and short terms for this fault system using geological, geodetic observations and empirical method. Using the geological data, the intermediate-term horizontal and vertical slip rates for AFS have been determined to be 2.8±0.2 and 0.27±0.03 mm/year, respectively. In addition, the short-term slip rates of the fault, based on the geodetic method (using displacement values of two GPS stations: HASH and DAMO) and assuming attenuation of 60% (to fold the sediment of South Caspian Basin and shortening of Talesh Mountain range), determined to be 1.23±0.03 and 2.05±0.05 mm/year for the horizontal and vertical slips, respectively. Finally, evaluation of the slip rate using empirical relationship yields 10 mm/year for the entire fault system, which seems rather implausible.

Seismotectonic, rupture process, and earthquake-hazard aspects of the 2003 December 26 Bam, Iran, earthquake

Geophysical Journal International, Sep 1, 2006

The catastrophic 2003 M w 6.6 Bam earthquake in southern Iran attracted much attention, and has b... more The catastrophic 2003 M w 6.6 Bam earthquake in southern Iran attracted much attention, and has been studied with an abundance of observations from synthetic aperture radar, teleseismic seismology, aftershock studies, strong ground motion, geomorphology, remote sensing and surface field work. Many reports have focused on the details of one or other data type, producing interpretations that either conflict with other data or leave questions unanswered. This paper is an attempt to look at all the available data types together, to produce a coherent picture of the coseismic faulting in 2003 and to examine its consequences for active tectonics and continuing seismic hazard in the region. We conclude that more than 80 per cent of the moment release in the main shock occurred on a near-vertical right-lateral strike-slip fault extending from the city of Bam southwards for about 15 km, with slip of up to 2 m but mostly restricted to the depth range 2-7 km. Analysis of the strong ground motion record at Bam is consistent with this view, and indicates that the extreme damage in the city can be attributed, at least in part, to the enhancement of ground motion in Bam because of its position at the end of the northward-propagating rupture. Little of the slip in the main shock reached the Earth's surface and, more importantly, aftershocks reveal that ∼12 km vertical extent of a deeper part of the fault system remained unruptured beneath the coseismic rupture plane, at depths of 8-20 km. This may represent a substantial remaining seismic hazard to the reconstructed city of Bam. We believe that some oblique-reverse slip (up to 2 m, and less than 20 per cent of the released seismic moment) occurred at a restricted depth of 5-7 km on a blind west-dipping fault that projects to the surface at the Bam-Baravat escarpment, an asymmetric anticline ridge that is the most prominent geomorphological feature in the area. This fault did not rupture significantly at shallow levels in 2003, and it may also represent a continuing seismic hazard. Widespread distributed surface ruptures north of the city are apparently unrelated to substantial slip at depth, and may be the result of enhanced ground motion related to northward propagation of the rupture. The faulting at Bam may be in the early stages of a spatial separation ('partitioning') between the reverse and strike-slip components of an oblique convergence across the zone. Such a separation is common on the continents, though in this case the slip vectors between the two faults differ only by ∼20 • as a substantial strike-slip component remains on the obliquereverse fault. The Bam earthquake is one in a series of large earthquakes involving faulting along the western edge of the Lut desert. In addition to the unruptured parts of the faults near Bam itself, continuing and substantial hazard is represented by unruptured neighbouring faults, particularly blind thrusts along the Jebel Barez mountains to the south and strike-slip faulting at Sarvestan to the west.

Neotectonics and paleoseismology of the North Tabriz Fault, Azerbaijan Region, Northwest Iran

Journal of Asian Earth Sciences