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EN
In this study, fuzzy logic modeling is applied to a complex and nonlinear set of data to predict both horizontal and vertical peak ground accelerations in Iranian plateau. The data used for the model include an up-to-date seismic catalogue from earthquakes in Iran for prediction of both horizontal and vertical acceleration of a probable earthquake. Fuzzy logic toolbox on MATLAB program was used for modeling. Earthquake magnitude ranging from 4 to 7.4, source-to-site distance from 7 to 80 km and three diferent site conditions were considered: rock, stif soil and soft soil. Results are compared with those from worldwide and regional attenuation relationships, which show the higher capability of the model in comparison with the other models. After training the model, testing of the fuzzy model with the remaining data set was performed to confrm the accuracy of the model. Changes in the peak ground accelerations in connection with changes in input parameters are studied which are in agreement with basic characteristics of earthquake input motions.
EN
In the world, people are increasingly exposed to natural hazards such as earthquakes. To this end, seismic risk mapping remains an essential topic of study in order to minimize their destructive effects. These maps are needed for both seismic risk management and for the design of infrastructure. The challenge is to take into account local information provided by seismic sources (historical seismicity) as well as information related to active tectonic faults. In this article, we calculated the seismic risk in the Mascara Mountains (western Algeria) using the geometric characteristic of known faults. This study is based on an important collection of a tectonic database of these faults (Nature, geometry and geological context). This information is relevant for their seismic potential. Indeed, by including these formations we tried to compute the seismic risk this region characterized by weak seismicity. Our results show more or less alarming facts. Indeed, the magnitude values calculated are between 4.85 and 7.25, whereas the magnitudes obtained by experimental seismicity do not exceed 6 on the Richter scale. The values of the maximum ground acceleration (PGA) are between 0.03 and 0.28 g. These results were compared with assessments made on the basis of historical seismicity; the maximum values obtained do not exceed 0.2 g. The higher values of magnitude calculated from the active faults is due to: (i) the nature of the faults (inverse, normal and strike slip), (ii) the geometry (length and depth) and (iii) that some of these faults may have an aseismic character.
EN
We investigated ground response for Baku (Azerbaijan) from two earthquakes of magnitude M6.3 occurred in Caspian Sea (characterized as a near event) and M7.5 in Shamakhi (characterized as a remote extreme event). S-wave velocity with the average shear wave velocity over the topmost 30 m of soil is obtained by experimental method from the VP values measured for the soils. The downtown part of Baku city is characterized by low VS30 values (< 250 m/s), related to sand, water-saturated sand, gravel-pebble, and limestone with clay. High surface PGA of 240 gal for the M7.5 event and of about 190 gal for the M6.3 event, and hence a high ground motion amplification, is observed in the shoreline area, through downtown, in the north-west, and in the east parts of Baku city with soft clays, loamy sands, gravel, sediments.
EN
Seismic hazard assessment for Quetta is carried out using probabilistic seismic hazard analysis technique based on area sources and augmented by line source used for the first time in Pakistan. Seismic data has been collected and analyzed in spatial and temporal domains. Five Seismic Zones have been modeled in line with tectonics of the region with b-value of 1.14 using regression. The b-value is slightly higher, which is attributed to the fact that aftershocks were not removed as it distorted the dataset. Five fault sources are modeled, with three as reverse and two as strike-slip with 7.8 as maximum magnitude. Mach Structure is included in the tectonics for the first time. The attenuation relation used in the present study is recommended by various researchers. The expected Peak Ground Acceleration for 500-year return period is 4.79 m/s2 for rock outcrop and characterized as very high. Furthermore, variation in spectral acceleration within Quetta city is observed, for which spectral curves are developed for four different places.
EN
Alexandria , as a second major city of Egypt, becomes nowadays a site for new developmental projects. Therefore, the seismic hazard analysis would be essential to mitigate the earthquake disaster in the region. The seismic hazard maps of different non-exceedence probability for Alexandria are presented. The obtained results indicate that Alexandria is highly affected by earthquakes are generated north of Red Sea and its two branches (Gulf of Suez and Gulf of Aqaba). Recently, the southwest Cairo (Dahshour district) is reported as a source region and poses an effect on the new constructions in Alexandria. Detailed seismic hazard estimation has been carried out for three important constructions: Alexandria Library, Stanley Bridge and the fort of Qaitbay (old Alexandria lighthouse). At the three sites, four intensity levels have been examined. The annual expected number of earthquake, the return period, and the probability of occurrence were calculated for each intensity level. The obtained results indicate that the return period of intensity 5.0 for the Alexandria Library and Stanley Bridge is about 47 years with 2.0% probability of occurrence. Thus, Alexandria Is and area of moderate seismic hazard.
EN
This paper describes cross-border earthquake hazard maps calculated in terms of macroseismic intensities and peak ground accelerations (PGA) for the Czech Republic, Poland and Slovakia (CZ-PL-SK). The study has been done in the framework of the Global Seismic Hazard Assessment Program (GSHAP). The new earthquake parametric catalogue for CZ-PL-SK was used. The catalogue represents an updated, revised and comprehensive seismicity database without boundary problems. Earthquake data have been normalized to obtain a reliable annual recurrence graph for each seismic region and the maximum expected earthquakes have been estimated. Calculated attenuation laws allowed more advanced earthquake hazard maps to be defined. Using Cornell's standard probabilistic method, the hazard maps were calculated for the return periods 475, 1000, and 5000 years. For the period of 475 years, good coincidences were found when comparing this newely calculated intensity map with that of Grunthal for Germany (D) and Austria (A); and the PGA map with the effective ground acceleration map for Austria by Lenhardt.
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