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In the present study a set of two deterministic earthquake scenarios (expressed in peak ground acceleration and macroseismic intensity MSK) are generated for the city of Sofia - the capital of Bulgaria. The study is guided by the perception that usable and realistic, based on both local seismic history and tectonic setting, ground motion maps to be produced for urban area. The city is situated in the center of the Sofia area that is the most populated (the population is of more than 1.2 mil. inhabitants), industri...

In the present study probabilistic earthquake, scenarios for the city of Varna the third-largest earthquake-prone city in Bulgaria are presented. The probabilistic hazard for a city is obtained by integrating the effects of ground motion from earthquakes of different size occurring at different locations within different seismic source regions and with different frequencies of occurrence. The ground motion maps for the city of Varna are generated combining via GIS, source geometry, earthquake occurrence model, max...

The purpose of this study is to shed light on the question of what the possible consequences will be on people and the building stock of a strong earthquake for the city of Varna. A seismic risk assessment methodology is used, which was approved by the Ministry of Regional Development and Public Works of the Republic of Bulgaria. The seismic impact is determined based on a detailed deterministic study of the seismic hazard. Initially, an assessment of the seismic vulnerability of the building stock is made based o...

In the present study deterministic earthquake scenarios for the city of Varna - the thirdlargest city in Bulgaria are presented. By deterministic scenario, it is mean a representation of the severity of ground shaking over an urban area, using one or more hazard descriptors. The assessment of seismic hazard and generation of earthquake scenarios is the first step of seismic risk evaluation and society prevention. Seismic history of Varna shows that the hazard for the city is mainly influence by the earthquakes occ...

-he space-time distribution of earthquakes is of substantial importance for understanding the physics of the earthquake generation process. Earthquakes can be analyzed as a time series of events that result from the released strain in the earth's crust. The study of the space-time distribution of earthquakes using statistical methods reveals many of their characteristics. Sequences of seismic events affect both spatial and time distribution of earthquakes. It is necessary to know the statistical characteristics of...

The present study focuses on the assessment of station corrections for eleven seismic stations from the national network of National Operative Telemetric System for Seismological Information (NOTSSI). Station corrections are obtained by calculating the ratio of the spectrum of the horizontal components of the signal to the spectrum of the vertical component (H / V). Records of S-waves from 20 local and regional earthquakes are analyzed. The values of A0 - site-effect and f0 - resonant frequency were obtained. Acco...

Eleven stations of the Bulgarian seismological network - National Operating Telemetry System for Seismological Information have been used for an assessment of the stations' corrections (site effect), to account for the impact on the seismic waves of the low-density layer immediately below the seismic stations, amplifying the signal. Nakamura's method for calculating the ratio of the spectrum of the horizontal component to the spectrum of the vertical component (H-to-V) is applied. Data from 20 local and regional e...

Global seismic risk and vulnerability to earthquakes are increasing steadily as urbanization and development occupy more areas that a prone to effects of strong earthquakes. The assessment of seismic hazard and generation of earthquake scenarios is the first link in the prevention chain and the first step in the evaluation of the seismic risk. The territory of Bulgaria represents a typical example of high seismic risk area in the eastern part of the Balkan Peninsula. Over the centuries, Bulgaria has experienced st...

The earthquakes are among the most common natural events in Bulgaria. Earthquakes represent a societal challenge as well as globally necessitating practical and operational solution for mitigating risk and reducing losses. This is achievable though earthquake risk assessment. The assessment of seismic risk is based on procedures for integration of seismic hazard and seismic vulnerability of the bearing structures of the building stock. The building stock is divided into three main groups, taking into account the s...

The territory of Bulgaria represents a typical example of high seismic risk area in the eastern part of the Balkan Peninsula. The spatial distribution of seismicity in Bulgaria is uneven, which gives reason to group earthquakes into geographically defined zones - seismogenic zones. In the present study the Sofia seismogenic zone will be examined. Sofia seismogenic zone is located in southwestern Bulgaria - the area with pronounces tectonic activity and proved crustal movement. The capital of Bulgaria - the city of...

In order to determine the effects of strong earthquakes for a given settlement, it is necessary to solve several tasks in a few stages. The first task is identification of the building stock for the surveyed area. The assessment of the effects of strong earthquakes is based on procedures for integration of seismic hazard and seismic vulnerability of the bearing structures of the building stock. The building stock is divided into three main groups, taking into account the specificity of the building and the availab...

Correlation studies have been made between the gravitational field (Bouguer anomalies - G) and the magnetic field (common vector (T) and the vertical component dZ) for the territory of Bulgaria. The map data is in digital format, which makes it easier to calculate. The correlation itself is estimated from -1 to 0 and from 0 to +1, which means that a positive correlation is possible in the case of increased values of both parameters and vice versa - decreasing values are associated with reduced values. This forms a...

Earthquakes are the deadliest natural disasters affecting the human environment. Global seismic risk and vulnerability to earthquakes are increasing steadily as urbanization and development occupy more areas that a prone to effects of strong earthquakes. Furthermore, uncontrolled growth of mega cities in highly seismic areas in the world is often associated with the construction of buildings and infrastructure, inconsistent with the regional seismo-tectonic features and seismic hazard. The assessment of seismic ha...

We analyze a series of data in the ultra-low frequency (ULF) range of geomagnetic variations, which are collected from search coil instrument and acquisition system at Panagyuriste, Geomagnetic Observatory (PAG), Bulgaria, a part of South European Geomagnetic Array (SEGMA, http://sole-terra.aquila.infn.it/it/), and data for seismic noise collected at three Bulgarian seismic stations (VTS, RZN and KDZ part of National Operative Telemetric System for Seismological Information) and three Turkish seismic stations (GOM...

In this research, the term risk follows the definition by the United Nations (UNDRO [1]) and refers to the expected losses from a particular hazard to a specified element at risk in a particular future time period. In our case, population exposure refers to the human occupancy of hazard zones in Bulgaria, or the population present within the hazard area that would be potentially directly affected by an event. Placed at the central part of the most seismically active region in Europe, the territory of Bulgaria is s...

We analyze the micro-seismic noise recorded at five seismic stations ? DEC, DJJ, FMP, MWC and RPV. They operate within CI: Southern California Seismic Network (SCSN), USA. The data set is collected from 01 July 2018 till 31 July 2019 and all seismic events with a magnitude Mw?4 are excluded. Our main goal is to find the effects of seismic noise synchronization between different seismic stations using data relevant to the vertical seismic components. The width of the multifractal spectrum, the spectral exponent and...