Search

Quantitative assessments of seismic hazard in seismically active areas depend to a large extent on the intensity-distance attenuation laws which are used in calculations. To account for epistemic uncertainty in the nature of seismic effects, it is recommended to perform probabilistic seismic hazard analysis using several different attenuation relationships. The most effective tool for their selection is the ranking procedure which consists in attributing a weight to one or another equation depending on the degree of compliance between the equation-based seismic effects and the real experimental data available for the region under study. The article presents the results of ranking intensity attenuation laws derived for Central Asia. Ranking was carried out by LH and LLH methods. Based on the ranking results, these has been made a generalized attenuation model used subsequently in PSHA for Uzbekistan. Consideration was given to three alternative models of seismic sources: area sources, active faults, and seismogenic zones. Parameterization of the models considered involved determining seismic potential, frequency of recurrence of earthquakes of different energy levels, and the predominant type of motions in each earthquake source. Seismic zoning maps of Uzbekistan in points of the MSK-64 intensity scale have been compiled for different probabilities of occurrence of non-exceedance level earthquakes in the next 50 years.

The presented article is relevant, as Kazakhstan is the first of the countries of the Central Asian region that has moved to the probabilistic seismic hazard assessment and seismic zoning at the regulatory level, consistent with the basic principles of Eurocodes. The methodology used is being improved in accordance with global trends and includes both domestic developments in the identification and parameterization of zones of possible earthquake sources, and the advantages of the Western engineering approach. However, the accuracy of estimates is strongly influenced by the weak development of seismological networks in Kazakhstan, poor knowledge of active faults, insufficient involvement of local specialists in significant international research projects. The current state of seismic hazard assessment in Kazakhstan is presented. The aim of the article was to highlight the developments in the country in recent years in this field of research. The stages of the probabilistic seismic hazard assessment (PSHA) development, methodological features in comparison with Central Asian countries, significance for the seismic safety of the country, the achieved level and difficulties are considered. The existing normative maps of seismic zoning based on PSHA and maps developed during current projects are characterized. The development of the modern probabilistic assessment is extremely relevant for the highly seismic areas of Kazakhstan. It is dictated by the need to update seismic design standards and the country's declared harmonization of the construction regulatory framework with the European building codes. [ABSTRACT FROM AUTHOR]

The article discusses the initial, including completely new, materials on strong earthquakes of the early Middle Ages in the Derbent sector of the West Caspian Sea coast. Historical and written material, stone wall engravings, and archaeological, seismogeological, and late graphic (iconography) information are presented and discussed. Geodynamic features are taken into account; GPS measurement results are also used. The problem of a strong earthquake in 741–743 AD is presented in a new light. The article reviews very inaccurate and contradictory parametric characteristics of strong earthquakes from the 6th century to the present published in Russian and English scientific papers and seismic catalogs. The structural-geodynamic situation in the coastal sector under consideration is specified and the characteristics of seismogenic faults and their kinematics are refined. The eastern border of the Dagestan Mountains in the studied section is considered as a high-order regional tectonic suture. The sources of single strong events in the early Middle Ages correlate with specific active faults and are considered in accordance with their kinematics. The article compares the results obtained from general seismic zoning maps of the Russian Federation reflected on different time interval maps, including the latest generation GSZ-2015 and GSZ-2016 maps (GSZ—general seismic zoning). As a result, the hazard rate for the studied section is reduced in comparison to what is now officially accepted. [ABSTRACT FROM AUTHOR]

The article continues work aimed at improving the general seismic zoning (GSZ) for the territory of the Russian Federation. Studies on updating the current regulatory maps OSR-97 are stimulated by the State Program aimed at enhancing the sustainability of life-support systems in seismic regions of the country. On the other hand, an update of the OSR-97 maps is also required in accord with the traditional regular revision every 10 years since 1937. In 1991-1997, a set of OSR-97 probabilistic maps was compiled for the first time, instead of a single deterministic map. The set was created for the design and construction of buildings with different categories of liability and service life. In 2010-2014, two versions of the new maps (OSR-2012 and OSR-2014) based on different approaches to modeling of seismic regime of earthquake sources were developed. The approaches are as follows: (1) exponential averaging of earthquake frequency-magnitude relationships throughout the range of magnitudes and (2) discrete time presentation in the form of histograms separately for different magnitudes. The first type of charts is used to create maps OSR-2012, and the second one is used for maps OSR-97 and OSR-2014. The purpose of this article is to demonstrate the most important aspects of seismological parameterization affecting seismic hazard assessments. This relates primarily to the dynamics of regional and global integration of seismic processes, because probabilistic seismic hazard analysis is based on the paradigm of stationarity of the long-term seismic regime. A comparative analysis of the information content of the maps OSR-97, OSR-2012 and OSR-2014 is performed. The seismic hazard assessments obtained are compared with the data on seismic effects of strong and the strongest earthquakes, including paleoseismogeological reconstructions, historical seismic events, and the earthquakes of instrumental period of seismic observations. We conclude that the set of maps OSR-2014 can replace the normative maps OSR-97. [ABSTRACT FROM AUTHOR]

Abstract: Changes expected in Mexico City''s seismic response due to land subsidence caused by groundwater extraction are examined. Settlements of the land surface observed in the recent past are compiled and processed to predict regional subsidence in the near future. This information is used in combination with the iso-depth and iso-period maps stipulated by the building code to estimate the compaction of surface sediments and the shortening of soil periods. The time-progressive evolution of the official seismic zoning maps and the associated site-specific response spectra is predicted. The same is done with spectral response contours expressed in terms of the site and structure periods. The subsidence effects are considered through an impact factor, which represents the increase or decrease in the spectral ordinates with respect to the current values specified for design purposes. The detrimental or beneficial effects depend on the relative values of the structure and site periods. [Copyright &y& Elsevier]