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Iran is located in a seismically active region and exposed to seismic activity from many seismic sources and active faults. Probabilistic seismic hazard assessment is the basis for many pre and post-earthquake risk management issues. Definition and parameterization of active faults and seismic sources are among the most important aspect for reliabl...
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The Alborz Mountains are among the areas exhibiting high tectonic and seismic activity in northern Iran. Studying key parameters of tectonic structures, including quantitative analysis and observational studies, in such active regions is essential to identify potential active faults and assess the consequent seismic hazards. This study focuses on s...
This study presents the spatial distribution of a grid-based probabilistic seismic hazard model at the surface level for the Kerman region in central-east Iran, using a hybrid site condition model. The hazard model has provided the variation of the peak ground acceleration (PGA), and 5% damped spectral accelerations (SA) at the fundamental periods...
The studies on seismic hazard analysis and zoning in Iran comprises the classical analysis of seismic sources using the seismotectonic and seismicity information. These analysis is performed during the last 3 decades based on the deterministic and probabilistic approaches. A logic tree was used to take into account the different ways for determinat...
Le zonage sismotectonique et l'examen critique des études et des cartes des aléas sismiques en Iran et au Moyen-Orient ont indiqué la nécessité de réévaluer les paramètres sismiques et de développer desétudes des aléas sismiques. Telles sont les questions critiques pour le développement de cartes des dangers sismiques : base de données actualisée d...
The 2017 Malard and 2020 Damavand moderate crustal earthquakes (Mw 4.8) occurred about 40 km west and about 55 km northeast of Tehran, the capital and economic heart of Iran, with a metropolitan population of over 15 million. Seismic hazard assessment in the region has been affected by few historically documented destructive earthquakes with magnit...
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... The local catalog of IRSC (Iranian Seismological Centre, http://irsc.ut.ac.ir/) was given higher priority for determining earthquake focal depth. For 3 events with no reliable depth estimates, the Scherbaum et al. (2004) equations were applied to estimate focal depth using (Zolfaghari and Darzi 2014) moment magnitude and style-of-faulting as inputs. In order to avoid unbiased results in terms of earthquake depth, only earthquakes with focal depth less than 40 km (92% of earthquakes) were allowed in the regression analyses. ...
New models are developed for the prediction of vertical-to-horizontal (V/H) spectral ratios of peak ground acceleration (PGA), peak ground velocity (PGV), and 5%-damped elastic response spectra for periods ranging from 0.01 to 10 s. The models use moment magnitude, source-to-site distance, style-of-faulting (SoF), and site classification terms as independent variables. The study is based on a well-compiled Iranian ground-motion databank, consisting of 1350 (*3) three-component accelerograms generated by 370 earthquakes. Only records with known measured time-averaged shear-wave velocity in the uppermost 30 m (VS30) are used for regression analyses. The presented models are valid for moment magnitude ranging from 4.5 to 7.4, distance up to 200 km, and for earthquakes with reverse and strike–slip fault mechanisms. Four alternative mathematical forms are evaluated in terms of magnitude and distance in order to find the optimal functional form for reliable prediction of V/H ratios. Out of four proposed forms, two were chosen for further investigation. The point source (hypocentral and epicentral) as well as extended source (rupture and Joyner-Boore) distance metrics are employed to derive four models. The overall validity of the proposed models is examined by detailed residual analyses as well as comparison with some of the local and regional predictive V/H models. Our proposed models showed significant reduction in the total standard deviation across all periods. The proposed V/H models facilitate assessment of vertical components of response spectrum where horizontal component of response spectrum is known, using V/H spectral ratios as scaling factors.
... This database includes almost all significant and destructive earthquakes instrumentally recorded in the Iran territory. The spatial distribution of the epicenters of earthquakes used in this study is shown in Figure 1 along with a selection of mapped Iran active faults (Zolfaghari and Darzi, 2014). The triangles indicate strong-motion stations that recorded the events used in this study. ...
... The most important studies are those by Berberian et al. (1992Berberian et al. ( , 1999Berberian et al. ( , 2001, Jackson et al. (2002), Walker et al. (2003Walker et al. ( , 2004, Ambraseys et al. (2005), Hamzehloo (2005), Talebian et al. (2006), Nissen et al. (2007), and Copley et al. (2015). Where unknown (3 (Zolfaghari and Darzi, 2014). Thick lines mark the boundaries between the five different seismotectonic areas of Alborz-Azerbaijan, Kopeh Dagh, central-east Iran, Zagros, and Makran (Mirzaei et al., 1998). ...
... To cope with this lack of information, we carried out additional investigations to determine the most likely faulting mechanism. We estimated the SoF for earthquakes, where unknown, by scrutinizing: (a) the topographic map and tectonic setting of the near-source areas; (b) the characteristics of nearby active faults, such as the strike and dip angles, and documented preferential fault mechanism contained in a comprehensive Geographic Information Systems (GIS)-based fault database provided by Darzi (2012) and Zolfaghari and Darzi (2014); and (c) the available information about previous earthquakes associated with the candidate causative faults. The distribution of earthquakes with respect to SoF before and after these additional refined investigations is depicted in Figure 3b. ...
Presented herein is a new set of empirical models for prediction of horizontal peak ground velocity (PGV), peak ground acceleration (PGA) and 5%-damped elastic response spectra in the vibration period range 0.01-10 s in Iran. The models are based on a carefully curated databank of Iranian strong ground motions comprised of 1350 pairs of orthogonal horizontal acceleration time histories from 370 regional earthquakes with 4.5 ≤ Mw≤ 7.4 and source-to-site distances up to 200 km. The adaptive wavelet de-noising approach used for waveform processing in this study allows extending the range of oscillator periods for which predictions can be made. We investigated the possible regional dependency of strong ground motions from three different regions (Alborz-Azerbaijan-Kopeh dagh, Zagros, and Central Iran-Makran) of the Iranian Plateau through analysis of variance. Our results show that data from these regions can be combined into a single database as only a few magnitude-distance intervals exhibit significant regional differences. Local site effects are taken into account using a site classification scheme based on VS30. The predictive models also include style-of-faulting terms. Due to paucity of data for normal faulting events, the applicability of the proposed attenuation models is limited to unspecified, strike-slip and reverse style-of-faulting. We propose four models that employ point-source (hypocentral and epicentral) and extended-source (rupture and Joyner-Boore) distance metrics, to enhance the flexibility of the prediction tool within the context of seismic hazard assessment studies. The results of between- and within-event residuals show that the proposed new models are unbiased. We present a detailed comparison of our results with a selection of local, regional and global predictive models developed by other authors.
