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Liquefaction hazard analysis is critical to the safety and cost-effectiveness of structures. Ramsar, the westernmost city of northern Iran's Mazandaran province, borders the Caspian Sea to the north. Since the soil strata of the Ramsar region are predominantly composed of low-grade sand and the groundwater is at low depths, it is highly vulnerable to liquefaction. Understanding how sedimentary basins react to seismic energy generated by earthquakes is a major concern for seismic hazard assessment and risk analysis. The primary purpose of this study is to determine the distribution of the natural frequency value, the amplification factor value and the soil vulnerability index. These were carried out as indicators for potential liquefaction sites in the city of Ramsar based on measurements of seismic ambient noise or microtremors. In this regard, ambient seismic noise was collected at 100 stations in the Ramsar region by Nanometrics Trillium40s intermediate sensors. Data are processed using the horizontal-to-vertical spectral ratio (HVSR) method provided by Nakamura (1989). Based on the results, the vulnerability index Kg is determined, which can be used as a parameter for calculating the region's liquefaction potential. Huang and Tseng (2002) suggested that the HVSR of microtremor data can be a good alternative indicator of the liquefaction potential of an area. It is revealed by previous researchers that improving the accuracy of geology and geomorphology-based liquefaction susceptibility map is accomplished by supplementing it with subsurface data (e.g., SPT, CPT, shear wave velocity data). The results of this study show that with the use of seismic ambient noise, the accuracy of the assessment of liquefaction susceptibility and zonation improves substantially.

In this study, the ETAS model was used to identify the sequence of aftershocks in Kermanshah, west of Iran. We appraise the model's ability to track aftershock sequences based on two main shocks from 2017 and 2018. This evaluation shall cover progress toward the objectives set out in the ETAS model and done focusing on the two main shocks of 2017 and 2018, as well as recommendations for the Seismic maps. The experiments were conducted to analyze the possibility of comparing model results and providing more accurate estimates of aftershock sequences for the Kermanshah region in four selected windows over time. The setting quality of the four windows that were investigated, in this study, by the model theory has been selected in a way to allow the comparison of the formation of aftershock sequences after the main shocks, especially the 2017 earthquakes and 2018 in the Kermanshah region. The results of this research emphasize the importance of recording earthquake events in the approximation of subsequent events and show that the model has a reliable skill in recognizing aftershock sequences, even if the number of main shocks is small. Also, choosing the period for research should be such that it does not interrupt the sequence of aftershocks.

The Iranian Plateau has been subjected to destructive earthquakes throughout its history. Reliable assessment of the seismic hazard in this earthquake-prone region is therefore essential. Our study focuses on estimating the maximum earthquake magnitude as one of the main parameters of seismic hazard analysis. We implemented two quantitative approaches, namely, probabilistic and deterministic. The probabilistic method allows combining the historical (i.e. incomplete) and the instrumental parts of a catalogue with different levels of completeness and considers the uncertainties in earthquake magnitude determination. In this study, we used a unified, declustered, and complete catalogue of earthquakes in Iran, covering the period from the fourth century BC to 2019. We calculated the maximum possible magnitudes for hundreds of grid points by using the seismicity data in a 200-km radial region around each grid point. The maximum possible earthquake was observed to vary between 6.0 and 8.2, and the highest values were found in the Alborz-Azarbayejan seismotectonic province, Kopeh-Dagh, central east Iran, Makran, and the southeast Zagros. The lowest mmax values were found in the Persian Gulf, Arabian Platform, Esfahan-Sirjan region, and the Dasht-e-Kavir Desert in central Iran. As a second part to this study, we calculated the maximum credible earthquakes for 1103 identified major faults by using five empirical magnitude-scaling relationships. Our results were consistent with both the observed earthquakes and the seismic potential of the various seismogenic zones of Iran. The study results can be used in future seismic hazard analyses and have fundamental implications for mitigating seismic risk in Iran.

This paper describes the analysis performed within a blind prediction, devoted to study local amplification and retrieval of shear-wave velocity structure in Ramsar city, the westernmost city in Mazandaran province in North of Iran, it borders the Caspian Sea to the north. Ambient vibration data were collected in 80 single stations and also 20 array measurements, in an area of 730 km2. The collected seismic data were analysed using both single-station and array processing techniques all equipped with Nanometrics Trillium40s intermediate sensors. The array measurements were conducted using uniform circular arrays of six sensors with one sensor in the center and a recording time of 45 minutes. The maximum conceivable aperture was about 70 m. Horizontal-to-vertical spectral ratios were calculated showing resonance peaks around 0.8 and 10 Hz. A fundamental resonance frequency map is provided for Ramsar area. The modified SPAC and high resolution F-K (RTBF) methods were applied for surface-wave dispersion curves retrieval. Vertical components were analysed to retrieve Rayleigh-wave dispersion curves while horizontal motions allowed to extract Love-wave dispersion curves by applying RTBF. They were used as targets for numerical inversion jointly with Love-wave dispersion curves and Rayleigh-wave ellipticity curves obtained for each array measurements.

This study is the first attempt to apply fault-based and time-dependent seismicity models cooperatively for probabilistic seismic hazard assessment (PSHA) of the Kerman and adjacent areas (54–59° E, 28.5–34° N). For this study, almost all available literature and databases have been investigated to compile reliable information reported as instrumental, historical, and paleoseismological events, together with the geometry and kinematics information for active faults. This information systematically is integrated and contributed to PSHA. Conditional probabilities of occurrence for earthquakes greater than the maximum earthquake from which its standard deviation is deducted (M > Mmax − σMmax) are computed based on a Brownian passage time (BPT) model. The spatial distribution of the time-dependent peak ground acceleration (PGA) has been calculated, and spectral accelerations have been computed for three selected cities (Kerman, Rafsanjan, Ravar), with 10% probability of exceedance in 50 years. The time-dependent PSHA map for PGA shows variations from − 21 along the Gowk fault to + 32% near the Sabzevaran fault segments in comparison with the corresponding time-independent PGAs. The difference between the time-dependent and time-independent PGAs at most parts of the study area is negligible, especially at sites farther away from the faults, where the differences vary from − 7 to + 7%. Moreover, the difference between the time-dependent and time-independent spectral accelerations for Ravar and Rafsanjan cities is insignificant. However, this difference at periods of 0.1–0.3 s is significant in Kerman city. The results of this study provide a stimulus for considering time-dependency assumption and fault-based approach in future earthquake-resistant constructions required in Kerman and adjacent areas.

Introduction: Paying attention to oral health of the vulnerable groups, including pregnant women, is of particular importance. Because self-efficacy is a predictor of behaviors related to oral and dental health, this study was conducted to determine the effect of educational intervention on the self-efficacy related to the oral and hygiene among pregnant mothers. Methods: This was a quasi-experimental study performed on 100 pregnant women who referred to Yazd Karami General Health Center in 2020. Samples were objective-oriented and randomly divided into case and control groups (50 people in each group). The demographic questionnaire and Oral Hygiene Self-efficacy Questionnaire (OHSQ) were used. It included 19 items related to self-efficacy ,such as: brushing, flossing and visiting the dentist (with a score range of 0-76).The intervention was done during one month in four 60-minute training sessions. One month later, data from both groups were collected again. Data were analyzed using SPSS Version 21 software and paired t-test, independent t-test and Chi-square. Results: There was a significant increase in the mean of self-efficacy regarding flossing in the case group before (11.26 ±5.66) and after the intervention (14.06 ± 5.79) (P = 0.03). The difference in self-efficacy of flossing between the case and control groups (11.64 ±6.83) after the intervention was significant, as well. (P = 0.04). The total self-efficacy in the case group increased significantly before (41.00 ± 9.18) and after the intervention (46.34 ± 10.10) (P = 0.04), and between the case and control groups (41.32 ± 13.45) after the intervention, too, became significant (P = 0.04). Conclusion: Educational intervention can increase the self-efficacy related to oral and dental hygiene among pregnant mothers, especially with regard to the use of dental floss, and can be effective in maintaining their oral and dental health during pregnancy.

We assessed the effect of seasons and the tree species velvet maple (Acer velutinum Boiss), Hainbuche hornbeam (Carpinus betulus L.) and chestnut-leaved oak (Quercus castanefolia C. A. Mey.; Fagaceae) on nutrient fluxes (Na+, K+ and Ca2+) in throughfall (TF) and litter flow (LF) from January 2012 to February 2013. Potassium (K+) and calcium (Ca2+) in total TF and LF over the measurement period significantly differed between 3 the species (p

Knowledge about seismic ambient noise wavefield through decomposition into different participant waves is of special importance in geophysical studies. In this study, WaveDec technique (Maranò et al., 2012) as an array statistical signal processing technique was used to decompose seismic ambient noise wavefield and to estimate wavefield parameters. In this method, the measurements from all components of stations and parameters of interest are modeled jointly which leads to significant improvement in extracting characteristics of surface waves. Considering the contribution of both Love and Rayleigh waves in the wavefield, the method estimates the desired parameters including amplitude, phase, azimuth, wave number and the ellipticity angle (for the Rayleigh wave only) based on the Maximum Likelihood Estimation method. One of the main characteristic of WaveDec is estimating the ellipticity angle of Rayleigh waves. This is very beneficial in determining retrograde and prograde particle motion and also in mode distinction.In the WaveDec algorithm, the Truncated Newton method is used to optimize likelihood functions with respect to wavefield parameters. Furthermore, Bayesian Information Criterion (BIC) is used to select the best model and wave type determination (Rayleigh, Love, body wave or noise). Regarding a group of generated models for different wave types, the one with the smallest BIC is chosen.We examined consistency of WaveDec algorithm by applying different numerical optimization methods; Truncated Newton, L-BFGS-B quasi-Newton and simplex-based Nelder-Mead methods. Furthermore, different model selection criteria; BIC, Akaike Information Criterion (AIC) and Hannan–Quinn Information Criterion (HQC) were examined to study the quality of generated models. They possess different penalty terms to avoid overfitting the models on data. All possible pairs of optimization methods and model selection criteria were utilized and replaced in WaveDec algorithm. In order to compare the resultant dispersion curves of surface waves and ellipticity angle curves of Rayleigh waves, SESAME model M2.1 synthetic data and some seismic ambient noise measurements in Colfiorito basin in Italy (Array B) were analyzed.

In seismic hazard assessment studies, the estimation of site effects plays an important role. In recent years, using seismic noise has become increasingly popular because of their simplicity, low cost, and non-destructively. Seismic ambient noise wavefield investigation can be fulfilled by both single-station and array methods. The RayDec single station method is used to estimate ellipticity curve of Rayleigh wave based on Random Decrement (RD) technique by putting more emphasis on Rayleigh waves in compare to other participant waves in the seismic noise wavefield. In this study, to assess measuring the ellipticity of Rayleigh waves in an array of stations, Vector Random Decrement (VRD) technique is applied. The main idea is applying vector triggering condition on vertical components in an array of stations and selecting common triggering points. Those parts of signals where common points of all stations are detected would be included in further processing. It may lead to a lower number of obtained triggering points and insufficient convergence. To control the convergence, the vector of triggering conditions could be divided into some subsets. The maximum number of subsets can be estimated as the lowest integer of N/2 in which N is the number of stations in the array. Wherever, the common triggering points are detected on three components of the stations, the time windows with the same length are extracted. In the following, the signals in the mentioned windows are stacked and the ellipticity ratio is estimated by analyzing the energy content of the horizontal and vertical signals. In order to verify the method, synthetic circular array data are simulated using the FD code including five stations regularly placed on the circumference and a station in the center. Furthemore, the real array data recorded in Ramsar site (North of Iran) are used to study the method. The data included six Nanometrics trillium 40 seismic stations in which five stations placed on the circumference as well as a station at the center regarding to array aperture of about 15m. The retrieved ellipticity curves are evaluated and compared with the results of high resolution Rayleigh three component beam-forming (RTBF) method. The RTBF and VRD methods show good performance in recognizing the right flank of peak frequency while, the peak frequency and the left flank are better retrived using VRD method. Finally, the retrieved ellipticity curve from VRD alongside with the dispersion curves obtained from RTBF for both synthetic and real array data are used as targets in a joint inversion process to validate the shear wave velocity profile.

In this study, the decay of earthquake aftershock sequences of some major earthquakes in different tectonic regimes in the Iranian plateau is discussed. The studied earthquakes are Rigan [2010], Ahar-Varzaghan [2012], Goharan [2013], Sefidsang [2017] and Ezgeleh [2017]. The spatial and temporal windows are considered based on the method proposed by Gardner and Knopoff [1974] to compute decay parameters for each sequence. The decay rates of sequences were compared to well-known models to find the best fit for each sequence. The results showed that the modified Omori is the best fit for Ahar-Varzaghan and Ezgeleh sequences, for Rigan and Sefidsang sequences the modified Omori and the Kisslinger ones found as the best fits. The values of the p parameter of the Reasenberg and Shcherbakov models were larger compared to the Omori model, but the parameter of the Kisslinger model was slightly smaller compared to the Omori one. The c parameter showed an inverse relation to the threshold magnitude. The correlation between the p and c parameters and also the and the Gutenberg and Richter (G-R) parameters were investigated. In addition, we made use of a graphical method to analyze the seismic sequence of the Ezgeleh earthquake during 13 months after the main event. The graphical method was successful to estimate the occurrence of an event with an approximate magnitude of M=6.4 in the sequence.

Probabilistic seismic hazard analysis (PSHA) can accommodate various sources of uncertainties and it provides a rational framework for the precise portrayal of the hazard of a given region. Often, the information used in the PSHA is incomplete and uncertain; therefore, the question arises how the uncertainty of the input data affects the estimated hazard characteristics. In this study, sensitivity analysis (SA) was conducted to identify the most dominant inputs affecting the assessment of the key seismicity parameters (SPs), including the mean seismic activity rate λ, b value of Gutenberg–Richter, and the maximum possible earthquake magnitude $$m_{ \hbox{max} }$$ . The study was applied in five areas of Iran, for which such analyses have not been conducted in previous studies. Subsequently, Monte Carlo simulation was employed to determine the effects of the uncertain input parameters on PSHA relevant to spectral accelerations corresponding to 10% and 2% probability of exceedance at least once in 50 years. For this purpose, a unified and declustered earthquake catalogue was used for the five major seismotectonic provinces of Iran (Alborz-Azarbayejan, Zagros, Central-East Iran, Koppeh Dagh, and Makran). The results showed that the last (complete) part of the catalogue has a significant effect on the estimated value of seismic activity and the b value. In contrast, its influence is insignificant on the area-characteristic maximum possible earthquake magnitude, for which the most influential inputs are the maximum observed earthquake and its uncertainty. Furthermore, the uncertainties of the input SPs affected the seismic hazard estimates substantially and led to significant variability in the estimated ground motion characteristics.

Bayesian probability theory is an appropriate and useful method for estimating parameters in seismic hazard analysis. The analysis in Bayesian approaches is based on a posterior belief, also their special ability is to take into account the uncertainty of parameters in probabilistic relations and a priori knowledge. In this study, we benefited the Bayesian approach in order to estimate maximum values of peak ground acceleration (Amax) also quantiles of the relevant probabilistic distributions are figured out in a desired future interval time in Iran. The main assumptions are Poissonian character of the seismic events flow and properties of the Gutenberg-Richter distribution law. The map of maximum possible values of Amax and also map of 90% quantile of distribution of maximum values of Amax on a future interval time 100 years is presented. According to the results, the maximum value of the Amax is estimated for Bandar Abbas as 0.3g and the minimum one is attributed to Esfahan as 0.03g. Finally, the estimated values in Bayesian approach are compared with what was presented applying probabilistic seismic hazard (PSH) methods based on the conventional Cornel (1968) method. The distribution function of Amax for future time intervals of 100 and 475 years are calculated for confidence limit of probability level of 90%.

On November 12th 2017, a MW =7.3 earthquake struck near the Iranian town of Ezgeleh, close to the Iran-Iraq border. This event was located within the Zagros fold and thrust belt which delimits the continental collision between the Arabian and Eurasian Plates. Despite a high seismic risk, the seismogenic behaviour of the complex network of active faults is not well documented in this area due to the long recurrence interval of large earthquakes. In this study, we jointly invert InSAR and near-field strong-motions to infer the geometry of a flat fault and a kinematic slip model of the rupture. The kinematic slip distribution reveals an impulsive seismic source with a strong southward rupture directivity, consistent with significant damage South of the epicenter. We also show that the slip direction does not match plate convergence, implying that some of the accumulated strain must be partitioned onto other faults.

On 12 November 2017, a M W=7.3 earthquake struck near the Iranian town of Ezgeleh, at the Iran‐Iraq border. This event was located within the Zagros fold and thrust belt which delimits the continental collision between the Arabian and Eurasian Plates. Despite a high seismic risk, the seismogenic behavior of the complex network of active faults is not well documented in this area due to the long recurrence interval of large earthquakes. In this study, we jointly invert interferometric synthetic aperture radar and near‐field strong motions to infer a kinematic slip model of the rupture. The incorporation of these near‐field observations enables a fine resolution of the kinematic rupture process. It reveals an impulsive seismic source with a strong southward rupture directivity, consistent with significant damage south of the epicenter. We also show that the slip direction does not match plate convergence, implying that some of the accumulated strain must be partitioned onto other faults., Key Points The Ezgeleh earthquake ruptured a flat thrust fault in the Zagros fold and thrust beltKinematic slip modeling reveals a highly impulsive source with southward directivity, possibly causing the large damage in the areaThe direction of coseismic slip suggests a strain partitioning between thrust and unmapped strike‐slip faults

Due to the significant effects of CO2 emissions on climate change and global warming, as well as its serious hazards to human health, the prediction of CO2 emission is a vital issue. The main aim of this paper is to evaluate the power of the Inclusive Multiple Model (IMM) as a novel approach to predict CO2 emission in the agriculture sector of Iran. For the same, we implemented the environmental Kuznets curve (EKC) specification and data from 2003 to 2017 for 28 provinces of Iran. In the first level, various specifications were implemented for each of the Multiple Regression (MLR), Gaussian Process Regression (GPR), and Artificial Neural Network (ANN) models. In the second level, an IMM model was implemented for treating the outputs of the best specification out of the MLR, GPR, and ANN models as inputs to an ANN model. The performance of the models was compared with the Taylor diagram and innovation and unique graphs. Findings indicated that the IMM model with C C = 0.81 , RMSE = 0.69, the highest residuals between −5 and 5 (37.84%), and the lowest distance from observation points (1.857) estimated CO2 emission values more precisely. These improvements indicate that there are possible directions for future research activities. Due to the most accuracy of the IMM, it is recommended to use this method to predict CO2 emission to adopt appropriate policies for reducing air pollution.

Knowledge about ambient noise wavefield, through decomposition into different participant waves and determination of precise singularities in ellipticity curves, could be very beneficial to improve the obtained subsurface velocity structures. In this paper, two array processing methods; WaveDec and high-resolution Rayleigh three-component beamforming (RTBF) and four single-station methods; Horizontal-to-Vertical Spectral Ratio (HVSR) or H/V, HVTFA (H/V using time frequency analysis), RayDec (Random Decrement Technique) and DOP-E (Degree Of Polarization) are applied to decompose ambient noise wavefield and to extract dispersion and ellipticity curves of surface waves. Two sites with different geological and geophysical conditions are chosen to examine the results of the measurements. The first selected site is in the south of Tehran, Iran, as a site with a low impedance contrast structure. The second one is in the Colfiorito basin, Italy, as a major impedance contrast structure site. Wavefield decomposition resulted in Rayleigh and Love wave separation and also mode distinction. The decomposed modes of surface waves and ellipticity curves of Rayleigh waves are used in a joint inversion process. The retrieved shear-wave velocity profiles are in close agreement with previous studies in the mentioned sites.

Background Worldwide, at least 200 million people are affected by peripheral vascular diseases (PVDs), including peripheral arterial disease (PAD), chronic venous insufficiency (CVI) and deep vein thrombosis (DVT). The high prevalence and serious consequences of PVDs have led to the development of several diagnostic tools and clinical guidelines to assist timely diagnosis and patient management. Given the increasing number of diagnostic methods available, a comprehensive review of available technologies is timely in order to understand their limitations and direct future development effort. Main body This paper reviews the available diagnostic methods for PAD, CVI, and DVT with a focus on non-invasive modalities. Each method is critically evaluated in terms of sensitivity, specificity, accuracy, ease of use, procedure time duration, and training requirements where applicable. Conclusion This review emphasizes the limitations of existing methods, highlighting a latent need for the development of new non-invasive, efficient diagnostic methods. Some newly emerging technologies are identified, in particular wearable sensors, which demonstrate considerable potential to address the need for simple, cost-effective, accurate and timely diagnosis of PVDs. Electronic supplementary material The online version of this article (10.1186/s12938-018-0494-4) contains supplementary material, which is available to authorized users.

A reliable system that can simultaneously and accurately monitor respiration and cardiac output would have great utility in healthcare applications. In this paper we present a novel approach to creating such a system. This noninvasive, low power, low cost, contactless sensor is suitable for continuous monitoring of respiration (tidal volume) and cardiac stroke volume. Furthermore, it is capable of delivering this data in true volume (i.e., mL). The current embodiment, specifically designed for sleep monitoring applications, requires only 100 mW when powered by a 4.8 V battery pack and is based on the use of a single electroresistive band embedded in a T-shirt. Here, we describe the implementation of the device, explaining the rational and design choices for the electronic circuit and the physical garment together with the preliminary tests performed using one volunteer subject. Comparison of the device with a commercially available spirometer demonstrates that tidal volume can be monitored over extended periods with a precision of ±10%. We further demonstrate the utility of the device to measure cardiac output and respiration effort.

A recent paper in the March/April 2013 issue of Seismological Research Letters , “A Unified Seismic Catalog for the Iranian Plateau (1900–2011)” by Mohammad P. Shahvar, Mehdi Zare, and Silvia Castellaro (henceforth referred to as Shahvar et al. , 2013) provides a unified homogeneous earthquake catalog, for the period 1900–2011, particularly for seismic‐hazard assessment studies in Iran. They subdivide the territory of the Iranian plateau into two domains only according to seismicity to derive empirical relationships to convert the original magnitudes ( M s, m b, M L, and M N) to a uniform scale ( M w), applying standard least squares (SR) and inverted least squares (ISR) regression methods and orthogonal regression method (OR). Some contradictions in Shahvar et al. (2013) encouraged us to declare a few points. The distinction between seismotectonic zones is based on all available geologic, tectonic, geophysical, and seismological data. In other words, a seismotectonic zone is considered an area that under present‐day geodynamic regimes has an internally consistent tectonic setting and unified seismicity pattern (Ye et al. , 1993, 1995). Shahvar et al. (2013) claim that the Iranian plateau can de facto be divided into two domains only because seismicity in the Alborz and Central Iran zones show statistically undistinguishable features. In contrast, Karimiparidari et al. (2013) distinguish six seismotectonic zones based on Mirzaei et al. (1998) and Tavakoli (1996). It is noteworthy that the second author of the two concurrent inconsistent papers is in common. Based on Nowroozi (1971) and Bird et al. (1975), it is stated by Shahvar et al. (2013) that the continental Arabian shield subducts beneath the Zagros belt. However, local seismograph networks have found no reliable depths in the Zagros deeper than ∼20 km, even in places where deeper earthquakes were reported to have occurred (e.g., Niazi et al. , 1978; Tatar et al. , …

Since the invention of the 12-lead Electrocardiography (ECG) it is taught that only eight out of the twelve signals recordable from the nine exploring electrodes are linearly independent. It is also accepted practice the use of other four linearly dependent signals to add diagnostic efficacy. Unfortunately, quality and usefulness of the 12-lead signals is directly correlated with electrode placement precision and concerns have been raised around intentional misplacements of limb electrodes also for resting ECG. In this paper we show that with a simple modification to the recording front-end, nine independent signals (one per recording electrode) can be recorded. These signals can be used to reconstruct precisely the 12-lead signals (without information loss) and a plethora of other linearly dependent new signals that can open an unexplored frontier in cardiac illnesses diagnosis. While we need to carefully evaluate the clinical implications of our findings, we present here the proposed circuit and a case study (healthy subject) showing the number of signals achievable and we quantify the effect upon the ECG signals of one of the most common intentional misplacement of electrodes.

This study presents the results of probabilistic seismic hazard (PSH) deaggregation for 5%-damped 0.2 and 1.0 s spectral accelerations, corresponding to mean return periods (MRPs) of 50, and 475 yr for Tehran city. The aim of this paper is to quantify the dominant events that have the most contribution on ground-motion exceedance from the above mentioned hazard levels. The scenario earthquakes are characterized by bins of magnitude (M), source-to-site distance (R), and epsilon (ε). The results reveal that for Tehran city, the hazard is mainly controlled by local seismicity. Generally, as the spectral acceleration period increase, the contribution of larger and more distant scenario earthquakes to the overall seismic hazard increase.

The spatial autocorrelation (SPAC) method is a useful tool for interpreting ambient noise, and several theoretical tools based on this method are available for data collection, processing, and analysis. The method uses the three components of seismic microtremors recorded simultaneously with arrays of different configurations and yields dispersion curves of Rayleigh and Love waves. Existing theories of the SPAC method are based on an idealized circular array with an infinite number of stations (the continuous model). Errors due to the use of a finite number of stations have been derived theoretically for vertically polarized ambient noise. This paper presents an extension of that error theory to horizontally polarized ambient noise so that it is valid for a circular array with M uniformly spaced stations. The quantities that are obtained as the output of the SPAC method, however, depend on the ratio of the power spectral densities (PSDs) of Rayleigh and Love waves, which are difficult to identify beforehand. Instead we introduce a quantity, κ , that does not depend on the PSD ratio and therefore is more convenient for separating the properties of Rayleigh and Love waves. We derive an expression of κ for a finite, M-station circular array ( κ M) and compare it with what it should be in the continuous model ( κ T ). We illustrate κ M and κ T using field data from a site in Tehran and discuss their discrepancies. Finally, we demonstrate how we have estimated Love-wave phase velocities using the calculated κ M.

SUMMARY The microtremor seismic method using spatial autocorrelation (SPAC) processing is a useful tool for estimating the structure of subsurface layers and the shear wave velocities of sediments. This paper improves upon the well-known ‘Modified SPAC’ (MSPAC) method, which extends the SPAC formulae for discrete and nearly continuous circular arrays to handle arrays with regular and irregular azimuthal spacing. For finite circular arrays, extended MSPAC (EMSPAC) also takes into account the discrete character of the array, which has been inspired by the works of Okada. Also a new SPAC coefficient is proposed for a nearly continuous array. EMSPAC is applied to real data collected using a seven-station array, and its averaged SPAC coefficients and dispersion curves are compared to those obtained using MSPAC.

Seismic hazard assessment and zoning of the Kermanshah-Sanandaj region in western Iran is conducted using probabilistic approach. Two maps have been prepared to indicate the earthquake hazard of the region in the form of iso-acceleration contour lines. They display a probabilistic estimate of peak ground acceleration PGA over bedrock for the return periods of 475 and 50 years. A uniform catalog of earthquakes containing historical and instrumental events covering the period from the eleventh century A.D. to 2003 is used. Twelve potential seismic sources are modeled as area sources in the region. Seismicity parameters are evaluated using the method in which magnitude uncertainty and incompleteness of earthquake data are considered. Seismic hazard assessment is carried out for a grid of 357 points with 0.1° intervals using the SEISRISKIII computer program for the study area encompassed by the 46– 48° E longitudes and 34– 36° N latitudes. This region includes the most active segments of the Zagros Main Recent Fault; among them, the Sahneh and Nahavand faults have a well-known history of intense seismic activity. PGA values for this region are estimated to be 0.35 g and 0.20 g for 475- and 50-years return periods, respectively. DOI: 10.1193/1.2431210

A unified catalog of earthquakes in Iran and adjacent regions (the area bounded in 22º-42ºN and 42º-66ºE) covering the period of 4th century B.C. through 2012 with Mw≥4 is provided. The catalog includes all events for which magnitude have been determined by international agencies and most reliable individual sources. Since the recurrence time of maximum credible earthquake cannot be directly estimated from the mb, empirical formulae are established to convert mb to Ms, mb to Mw and Ms to Mw for each major seismotectonic province separately. The unified catalog is declustered using conjugated distance-time windows. In order to estimate completeness thresholds, magnitude-time (M-T) diagram and Stepp’s method are applied on the declustered catalog for each seismotectonic province. The magnitude of completeness (Mc) decreases with development of local and regional seismic stations. The results of present study are particularly important in seismic hazard analysis in Iran.

This article presents the results of disaggregation of ground motion hazard obtained for two of Iran’s urban centers, Kermanshah and Sanandaj. Disaggregation of peak ground acceleration (PGA) and spectral acceleration hazard corresponding to mean return periods of 475 and 50 years is performed. 12 area seismic sources in the study region as well as 15 area seismic sources in a 150-km distance from the region are delineated. The scenario earthquakes are characterized by bins of magnitude, M, source-to-site distance, R, and number of standard deviations, ε, that the ground-motion parameter is away from its median value for that M-R pair as estimated by a prediction equation. In most cases, the sources closer to the site dominate. Larger, more distant earthquakes contribute more significantly to hazard for longer periods than for shorter periods. Disaggregation plots can provide useful information on the distance and magnitude of predominant sources, which can be used to generate scenario earthquakes and select corresponding time histories for seismic design.

Surface waves have been used increasingly as an attractive tool to obtain near-surface shear wave velocity profiles. Inversion of Surface wave dispersion curves is demanding for most local-search methods due to its high nonlinearity and to its multimodality. Among many approaches which have been proposed for surface wave inversion so far, Intelligence Swarm algorithms effectively applied to solve it, and attempt to avoid trapping in local minima. In this paper, we proposed a new approach (Artificial Bee Colony ABC) to overcome above disadvantages. Bee algorithms form another class of algorithms which are closely related to the ant colony optimization. Bee algorithms are inspired by the foraging behavior of honey bees. To evaluate calculation efficiency and stability of ABC to inversion of surface wave data, we first inverted a broadband (1-30 Hz) synthetic dispersion curves from a simple model. After that we extended search space, added noise and ultimately limited the frequency band. Results from all synthetic data demonstrate that ABC can be used for quantitative analysis of Surface wave dispersion curves.

In this study first, we checked particle motion behavior of ambient noise recordings in Tehran. The results show the predominance of Rayleigh waves in ambient noise wave field. Then, we investigated H/V curves of ambient noise recordings. After modeling ellipticity curves of Rayleigh waves, we investigate coincidence of H/V ratio peak with the peak related to fundamental mode of Rayleigh waves. To sum up, in the desired area fundamental mode of Rayleigh wave accounts for the peak observed on the H/V curves, related to site resonance frequency.

Vehicle tracking is an essential requirement of any vision based Intelligent Transportation System for extracting different traffic parameters, efficiently. Handling inter-object occlusion is the most challenging part of tracking as a process of finding and following interested objects in a sequence of video frames. In this paper we present a system, based on code-book background model for motion segmentation and Kalman filter for tracking with a new approach for occlusion. This approach separates occluded vehicles based on longest common substring of chain codes. We use this tracking system to estimate some traffic parameters. Experimental results show the efficiency of the method