Iran experiences more intense earthquakes than Iraq due to tectonic differences
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The retrieved scientific sources document active tectonic plate convergence between the Arabian and Eurasian plates affecting both Iran and Iraq, but they lack a comprehensive comparative analysis directly establishing that Iran experiences systematically more intense earthquakes than Iraq due to these tectonic differences.
Recently, Iraq has experienced an unprecedented seismic activity, specifically, near the east boundary with Iran which reveals the need to re-evaluate the seismic hazard at this region. This study consists of two phases. The first is collecting the earthquake records covering the recent events till the end of November 2017 including the 12 November 2017 (7.3Mw) earthquake, and applying data processing to get the net data for independent events for the study area which were more than 4300 of net main earthquakes of Mw ≥ 4 and were used in the second phase. The second phase is applying the PSHA method by dividing the study area into a grid of small cells of size 0.5 0.5°and the hazard parameters were calculated at the center of each of these grid cells then, converting the final results to contours over the study area. It is found that the values increases towards the east-northeast and north due to the continued tectonic boundary convergence between the Arabian, Iranian and Turkish plates which produces intense earthquake activity. The design spectral acceleration at 0.2 and 1.0 seconds found to be 0.33, 0.17, 0.47, 0.25, 0.71, 0.35 g for Basra, Baghdad and Erbil, respectively. The comparison between the PGA values from this study and from the seismic hazards maps from Iraqi seismic codes of 1989, 1997 and 2016, for return periods of 475 and 2475 years, reveals the continued increase with time which reveals the need to updating the seismic hazard maps continuously.
Updated Probabilistic Seismic Hazard Assessment for Iraq/2018 | Civil Engineering Journal article Home About About the Journal Submissions Editorial Team Author fee(s) Current Archives Editorial Team Contact Register Login Search Register Login Updated Probabilistic Seismic Hazard Assessment for Iraq/2018 https://doi.org/10.28991/cej-0309199 PSHA Iraq Main Earthquakes PGA Spectral Accelerations Seismic Hazard. Authors Mustafa Shakir Farman alishf2013@yahoo.com Faculty Member, Technical Institute of Samawa, Al-Furat Al-Awsat University, Iraq. Ph.D.
student, Civil Engineering Department, University of Baghdad, Baghdad, Iraq., Iraq AbdulMuttalib Isa Said Prof., Faculty Member, Civil Engineering Department, University of Baghdad, Baghdad, Iraq., Iraq Share Vol. 4 No. 7 (2018): July Research Articles Downloads PDF Abstract How to Cite Metrics References License Recently, Iraq has experienced an unprecedented seismic activity, specifically, near the east boundary with Iran which reveals the need to re-evaluate the seismic hazard at this region. This study consists of two phases.
It is found that the values increases towards the east-northeast and north due to the continued tectonic boundary convergence between the Arabian, Iranian and Turkish plates which produces intense earthquake activity. The design spectral acceleration at 0.2 and 1.0 seconds found to be 0.33, 0.17, 0.47, 0.25, 0.71, 0.35 g for Basra, Baghdad and Erbil, respectively. The comparison between the PGA values from this study and from the seismic hazards maps from Iraqi seismic codes of 1989, 1997 and 2016, for return periods of 475 and 2475 years, reveals the continued increase with time which reveals the need to updating the seismic hazard maps continuously. Farman, M. S., & Said, A. I. (2018).
Updated Probabilistic Seismic Hazard Assessment for Iraq/2018. Civil Engineering Journal , 4 (7), 1610–1628. https://doi.org/10.28991/cej-0309199 More Citation Formats ACM ACS APA ABNT Chicago Harvard IEEE MLA Turabian Vancouver Download Citation Endnote/Zotero/Mendeley (RIS) BibTeX Downloads Download data is not yet available. [1] Ghalib & Aleqabi/JZS. "Seismicity, Velocity Structure and Tectonics of the Arabian Plate.” Journal of Zankoy Sulaimani 18 – 1 (Part-A) Pure and Applied Science (2016). doi.org/10.17656/jzs.10499
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[4] Mahmood, D.S., Khalifa, S., Jordanovski, L., Dojcinovski, D. "Seismic hazard evaluation and seismic zoning maps of Iraq.” Investigations for elaboration of preliminary seismic design code of Iraq, Building Research Center, Baghdad, Iraq, (1988). [5] McGuire, R.K.
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"Seismic motion and response prediction alternatives.” Earthquake Engineering & Structural Dynamics 7 (1979): 295-315. Doi: 10.1002/eqe.4290070402. [9] Al-Sinawi, S.A., Al-Qasrani, Z.O. "Earthquake Hazards Considerations for Iraq.” Proc. 4rth Int. Conference of Earthquake Engineering and Seismology, Tehran, Iran. (May 2003). [10] Boore, D. M., Stewart, J. P., Atkinson, G. M. (2014). "NGA-West2 Equations for Predicting PGA, PGV, and 5% Damped PSA for Shallow Crustal Earthquakes.” Earthquake Spectra 30(3) (August 2014): 1057-1085. Doi: 10.1193/070113EQS184M. [11] Chiou, B. S.-J., Youngs, R.R.
Doi: 10.5078/corssa-52382934. [21] Stepp, J.C. "Analysis of completeness of the earthquake sample in the Puget Sound area and its effect on statistical estimates of earthquake hazard.” Proceedings of the
Abstract
Doublet earthquakes with magnitudes of 6.2 (12:07) and 6.3 (12:08 GMT) on December 14, 2021 struck the SE Zagros in the range of the Mountain Frontal Fault (MFF) in south of Iran. By combining and processing the records of the seismic networks, mechanism of some of background seismicity and the aftershocks were solved and Coulomb stress maps of epicentral area were drawn. Reverse mechanism with a small strike slip component in some earthquakes were dominant, if north dipping E-W oriented plane is the active plane. Statistical investigation of the earthquakes parameters demonstrated that no considerable seismic gap was seen before the first mainshock. The 12:08 Fin earthquake, like other Mountain Frontal Fault dependent earthquakes, is associated with the probable development of anticlines in its vicinity, which is accompanied by a faulting process in and around the core. A small area of fractures with a maximum length of hundred meters and few centimeters opening were seen in the nearest main road. No coseismic mature fault related to this magnitude was observed in prospecting in high quality satellite images. The coulomb stress field revealed that the second shock and majority of aftershocks happened in area of increased stress produced by the first mainshock and second earthquake, respectively. Dimension and strike of coseismic rupture of the second event are estimated ~50 km and near ENE-WSW, respectively using both aftershocks elongation and special-temporal diagram of micro earthquakes. Northward directivity was seen for both shocks in their accelerograms of northeast and south of the epicenters. If MFF fault is supposed as causative fault for the second shock, second rupture was probability propagated from the south to the north, unilaterally. Based on northward dipping of the MFF, the rupture of second event could propagate from shallow depth (10 km, hypocenter) toward deep area (12 km, centroid) of the fault along N-S direction. If causative
The November 2021 Fin (SE Zagros, Iran) doublet earthquakes of reverse faults in a transpressional tectonic regime | Research Square Cite Share Download PDF Research Article The November 2021 Fin (SE Zagros, Iran) doublet earthquakes of reverse faults in a transpressional tectonic regime Majid Nemati This is a preprint; it has not been peer reviewed by a journal.
The 2021 Fin earthquake provided a new challenge to investigate the mechanism of earthquake, aftershocks and its relation and Coulomb analysis to illustrate tectonic in the area. This study tries to investigate the Dec. 14, 2021 earthquakes sequences using seismic data. Seismotectonic settings GPS data indicates a rate of ~21 mm/year for the convergence of Arabia-Iran in Persian Gulf with ~E10˚N direction (e.g. Vernant et al. 2004 ). According to seismotectonic of the area, the Zagros seismotectonic province has different behaviors from northeast to southwest that can be divided into several parts: the high Zagros, the simply folded belt and the Zagros foredeep.
Tectonophysics 241:193–224 Walker RT, Andalibi MJ, Gheitanchi MR, Jackson JA, Karegar S, Priestley K (2005) Seismological and field observations from the 6 November 1990 Furg (Hormozgan) earthquake: a rare case of surface rupture in the Zagros mountains of Iran. Geophys J Int 163:567–579 Harris RA (1998) Introduction to special section: Stress triggers, stress shadows, and implications for seismic hazard. Journal of Geophysical Research: Solid Earth 103(B10):24347–24358 Hatzfeld D et al (2010) The kinematics of the Zagros Mountains (Iran).
doi: 10.29382/eqs-2019-0000-00 Nemati M, Jafari Hajati F, Rashidi A, Hassan-zadeh R (2020) Seismology of the 2017 Hojedk earthquakes (M N 6.0- 6.1), Kerman province, SE Iran. Tectonophysics 780:228398 Nissen E, Ghods A, Karasözen E, Elliott JR, Barnhart WD, Bergman EA, Hayes GP, Jamal-Reyhani M, Nemati M, Tan F, Abdulnaby W, Benz HM, Shahvar MP, Talebian M, Chen L (2019) The 12 November 2017 Mw 7.3 Ezgeleh–Sarpolzahab (Iran), Eearthquake and active tectonics of the Lurestan arc 2. JGR-Solid Earth. 10.1029/2018JB016221 Okada Y (1992) Internal deformation due to shear and tensile faults in a half-space.
Bull Seismol Soc Am 82(2):1018–1040 Ottemöller L, Havskov J (2012) The earthquake analysis of SEISAN software, version 9.1, http://www.geo.uib.no/Seismologi/SOFTWARE/SEISAN_9.1 , 2022 Roustaei M, Nissen E, Abbassi M, Gholamzadeh A, Ghorashi M, Tatar M, Yamini-Fard F, Bergman E, Jackson J, Parsons B (2010) The 2006 March 25 Fin earthquakes (Iran)—insights into the vertical extents of faulting in the Zagros Simply Folded Belt.
Geophys J Int 156:506–526 Tatar M, Hatzfeld D, Ghafoury-Ashtiani M (2004) Tectonics of the Central Zagros (Iran) deduced from microearthquake seismicity. Geophys J Int 156:255–266 Toda S, Stein RS, Richards-Dinger K, Bozkurt SB (2005) Forecasting the evolution of seismicity in southern California: Animations built on earthquake stress transfer. Journal of Geophysical Research: Solid Earth 110:B5 Vernant P, Nilforoushan F, Hatzfeld D, Abassi M, Vigny C, Masson F, Nankali H, Martinod J, Ashtiani A, Bayer R, Tavakoli F, Che´ry J (2004) Contemporary crustal deformation and plate kinematics in Middle East constrained by GPS measurements in Iran and northern Oman.
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This paper evaluates the use of multisite (MS) probabilistic seismic hazard analysis (PSHA), which estimates the annual exceedance rate of a given level of ground motion in at least one of several sites as one of several possible results. For this purpose, (1) MS-PSHA is implemented through the Monte Carlo approach, taking into account various area sizes and correlation distances (<i>CD</i>s), and then (2) two proposals are represented as applications of MS-PSHA outcomes, both with reference to Sarpol-e Zahab City, a seismically active region located in the west of Iran. The first proposal attempts to determine the current code design probability of exceedance in at least one site, and the second one defines collapse prevention levels based on different probabilities of exceedance in at least one site. The efficiency of the results is discussed mainly by comparing them to recorded peak ground accelerations (PGAs) of three earthquakes, including the 2017 Sarpol-e Zahab 7.3 <i>M</i> <sub><i>w</i></sub> event that largely exceeded the code design spectrum. MS-PSHA results demonstrate reasonable performance both in determining design ground motions and evaluating current design code when the exact seismic parameters of the study area are used in the analysis. Moreover, developed code-type design spectra based on MS-PSHA provided safety against collapse compared to a recently occurring low-probability event. MS estimates for various <i>CD</i>s and probabilities of exceedance in at least one site can also provide flexible design strategies regarding the importance of a structure and expected damage on a regional scale.
The outputs of the proposed applications are (1) exceedance probability of Iranian code design spectrum in at least one site of several in Sarpol-e Zahab City and (2) adopted maximum considered earthquake (MCE) ground motions using MS-PSHA estimates and developed design-based earthquake (DBE)-level uniform hazard spectra. Following a review of fundamental concepts in Sect. 2 of this paper, Sect. 3 explains the studied area of interest for MS-PSHA and input parameters. It should be noted that in this section, the MS-PSHA analysis is implemented for Sarpol-e Zahab City in western Iran by defining three zones with different areas.
Sarpol-e Zahab City in Kermanshah Province, western Iran, is selected as an appropriate area in this study to implement MS-PSHA and examine its performance. This area is located along the Iran–Iraq border and is close to the convergent boundary of the Arabian and Eurasian tectonic plates, as well as the High Zagros Fault and the Mountain Front Fault (Yaghmaei-Sabegh, 2019 ). In recent years, this area has been hit by several large destructive earthquakes with all epicenters less than 40 km away. Table 1 provides the characteristics of these earthquakes. As presented, the recorded PGAs differ significantly from design PGAs adopted from Standard No. 2800 (2014).
The main characteristics of two local and regional GMPEs are reported in Table 3 . Notably, the two relationships used in this paper are based on data from crustal earthquakes in Iran and Turkey. We considered PGA as the intensity measure in all sites in our analysis. Figure 3 illustrates an example of a simulated catalog based on the Monte Carlo technique, which serves as the primary input for MS-PSHA. Fig.
According to this figure, the slope of the graph becomes steeper when the CD is increased from 10 to 20 km, indicating a significant difference between these two distances rather than others. Fig. 6 Dependence of MS-PGAs with a return period of 475 years on CD. Solid circles show individual MS-PGAs, and MS hazard curves are obtained by spline interpolation To evaluate the performance of MS-PSHA, we compared the results with the recorded PGAs of recent earthquakes in Sarpol-e Zahab City (see Table 1 ). First, the correlation function should be selected, which is adopted from Zafarani et al.’s study ( 2020 ) in this paper. Using Fig.
This choice can have two main advantages: (1) adopting ground motion levels with a low probability of exceedance is associated with uncertainty, as large, rare, and low-probability earthquakes play an important role in their estimation. As we know, considering these earthquakes is difficult in most cases due to limited sources, especially in areas with rare and limited seismic data. Therefore, higher exceedance probabilities resulting from MS-PSHA can help to reduce this uncertainty to some extent. (2) The collapse of a building can result in secondary damages and even a social crisis in the case of a lifeline element collapse.
Therefore, adopting a ground motion with a specific probability of exceedance in at least one site over a given time interval would allow us to consider the social risk aspect when defining the collapse prevention level. If we select the MCE ground motion and collapse prevention level based on the proposed approach and adopt DM based on single-site PSHA as the ground motion with a 10% probability of exceedance in 50 years, an issue arises due to the difference between these levels, decreasing building safety against collapse. For instance, for Sarpol-e Zahab City, based on single-site PSHA and Standard No.
This high probability may warn us about a possible social crisis due to probable damages to a very important structure in the next 50 years. To further examine the MS design spectrum, the response spectrum of the Sarpol-e Zahab 2017 earthquake is compared with the MS design spectrum with a 10% probability of exceedance in at least one site (Fig. 10 ). It should be noted that this is a preliminary performance evolution rather than an absolute validation of the MS design spectrum. According to Fig. 10 , the MS design spectrum represents reasonable estimates of SA at natural periods in which the response is maximum (0.22 s and 0.28 s) and also at shorter periods. Fig.
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