Aftershock probabilistic seismic hazard analysis (APSHA) is essentially useful for various earthquake engineering problems. In this paper, a series of aftershock seismic hazard analyses were conducted in western Zagros region in Iran using different approaches. The results were obtained in terms of exceedance probabilities of peak ground accelerations within different time intervals following the mainshock. The results were generally compatible with the recorded data; however, the accuracy depended on the causative fault geometry and spatial distribution of aftershocks. The accuracy decreased in shorter time intervals after the mainshock and also in longer time spans especially when strong aftershocks occurred. [ABSTRACT FROM AUTHOR]
This paper presents the development of new and simple empirical models for frequency content prediction of ground-motion records to resolve the assumed limitations on the useable magnitude range of previous studies. Three period values are used in the analysis for describing the frequency content of earthquake ground-motions named as the average spectral period ( T), the mean period ( T), and the smoothed spectral predominant period ( T). The proposed models could predict these scalar indicators as function of magnitude, closest site-to-source distance and local site condition. Three site classes as rock, stiff soil, and soft soil has been considered in the analysis. The results of the proposed relationships have been compared with those of other published models. It has been found that the resulting regression equations can be used to predict scalar frequency content estimators over a wide range of magnitudes including magnitudes below 5.5. [ABSTRACT FROM AUTHOR]
In this paper probabilistic seismic hazard assessment of Tehran for Arias intensity parameter is done. Tehran is capital and most populated city of Iran. From economical, political and social points of view, Tehran is the most significant city of Iran. Since in the previous centuries, catastrophic earthquakes have occurred in Tehran and its vicinity, probabilistic seismic hazard assessment of this city for Arias intensity parameter is useful. Iso-intensity contour lines maps of Tehran on the basis of different attenuation relationships for different earthquake periods are plotted. Maps of iso-intensity points in the Tehran region are presented using proportional attenuation relationships for rock and soil beds for 2 hazard levels of 10% and 2% in 50 years. Seismicity parameters on the basis of historical and instrumental earthquakes for a time period that initiate from 4th century BC and ends in the present time are calculated using Tow methods. For calculation of seismicity parameters, the earthquake catalogue with a radius of 200 km around Tehran has been used. SEISRISKIII Software has been employed. Effects of different parameters such as seismicity parameters, length of fault rupture relationships and attenuation relationships are considered using Logic Tree. [ABSTRACT FROM AUTHOR]
This paper presents a new empirical model to predict the mean period (T m) as a frequency-content parameter of earthquake record using the strong ground motions recorded in Iran during 1975–2019. An updated earthquake databank containing 2281 horizontal acceleration records was employed to develop the empirical model through a systematic fitting procedure. A simple functional form for the model was found as a function of epicentral distance (R), moment magnitude (M w), and the shear wave velocity averaged at the top 30 m of the recording sites (V s30). The proposed model is compared with three existing predictive models and the results are discussed in terms of magnitude, source-to-site, and site dependencies. [Display omitted] • A new GMPE for Tm based on an extensive database of earthquake records is presented. • More than 4500 Iranian strong ground motions were used. • We compared the predictive model with the models recently proposed to predict Tm. • The presented equation is applicable is earthquake engineering practice [ABSTRACT FROM AUTHOR]