Assessment of Seismic Hazard of Territory on Basis of Modern Methods of Detailed Zoning and Seismic Microzonation

Abstract

The new complex method of seismic hazard assessment resulted in creation of the probabilistic maps of seismic microzonation is presented in this paper. To study seismicity and analyze seismic hazard of the territory the following databases are formed: macroseismic, seismologic databases and the database of possible seismic source zones (or potential seismic sources-PSS) as well. Using modern methods (over-regional method of IPE RAS-Russia) and computer programs (SEISRisk-3-USA) in GIS technologies there were designed some probabilistic maps of seismic hazard for the Republic North Ossetia-Alania in intensity units (MSK-64) at a scale of 1:200 000 with exceedance probability being of 2%, 5%, 10% for a period of 50 years, which correspond to recurrence period of 2500, 1000, 500 years, correspondingly. Moreover, first the probabilistic maps of seismic hazard were made in acceleration units for the territory of Russia. The map of 5% probability is likely to be used for the large scale building, i.e. the major type of constructions, whereas the map of 2% probability should be used for high responsibility construction only. The approach based on physical mechanisms of the source is supposed to design the synthesized accelerograms generated using real seismic records interpretation. For each of the zoning subject the probabilistic map of the seismic microzonation with location of different calculated intensity (7, 8, 9, 9*) zones is developed (the zones, composed by clay soils of fluid consistency, which can be characterized by liquefaction at quite strong influences, are marked by the index 9*). The maps in accelerations units show the similar results. The complex approach based on the latest achievements in engineering seismology, can significantly increase the adequacy or foundation for assessments and reduce the inaccuracy in earthquake protected design and construction. Realization of investigations on mapping of seismic hazards such as detailed seismic zoning (DSZ) based on the most advanced field research methods and analysis of every subject of the Northern Caucasus separately on a scale of 1:200 000 gives the possibility to merge a bit unavailable, at first glance, schemes into geologically and geophysically quite reasonable map of DSZ for the Northern Caucasus with equal scale system of the source zones.

Complex Analysis of Geological Data and Use of Velocity Model of MMS on Central Caucasus Sections

“…The good exposure of bedrock in the mountainous and high-mountainous parts of the Central Caucasus and the state of exploration of numerous boreholes in applied purposes of foothill and flat areas give grounds to qualify certain intervals as parametric [6]. At the same time, the detailing and feasibility of the deep features of the Central Caucasus, which determines the level and effect of seismic hazard, still needs development [7]. This, unfortunately, was facilitated by the cessation from the end of the 1980s of works on the "System of regional study of the crust and upper mantle along the geotraverses laid through the drilling areas of deep and super deep boreholes" adopted in 1972 [8].…”

Development of a Unified Model of Geoinformation System for City Planning and Integration

“…Seismic hazard assessment is usually reduced to the calculation of the maximum possible seismic impacts that must be taken into account in case of construction in seismic regions. Seismic hazard is reflected in the maps of seismic zoning of a certain territory [3][4][5][6]. Depending on the tasks and necessary detail of seismic hazard mapping three levels of seismic zoning are considered in our country: general seismic zoning (GSZ) -for the entire territory of the country; detailed seismic zoning (DSZ) -for the limited areas and individual regions; seismic microzonation (SMZ) -for cities, settlements and construction sites.…”

“…As a result of numerous investigations on seismic hazard assessment in 2006-2013, the original maps of detailed seismic zoning (DSZ) of the Republic of North Ossetia-Alania, maps of seismic microzonation (SMZ) of the territories of cities and large settlements of North OssetiaAlania [7][8][9][10][11][12] have been created by the Geophysical Institute. It is obvious that cartographic materials should correspond to the world level, applicable to the spatial data, and, first of all, it must have the opportunity of direct inclusion in any modern information system.…”

Changes in the Qualitative Characteristics of Groundwater of the Ossetian Artesian Aquifer

“…The increase of groundwater hardness is observed in the northern (industrial) part of the city. According to preliminary data, it was caused by the anthropogenic impact on the geological environment [2]- [3] in the conditions of high exogenous [4] and endogenous hazards [5]- [7].…”