An integrated approach to assessing the geodynamic activity of the Earth's crust in the low seismic East Baltic region

<p>The East Baltic region (EBR), located on the ancient Precambrian East European Craton, is characterized by low seismic and deformational activity. The EBR is located at a distance of about 2000 km from the divergent zone in the North Atlantic and from the convergent zone in the Mediterranean Sea.</p><p>Nevertheless, historical and modern earthquakes have occurred in the EBR. Historical earthquakes occurred in 1616 (<em>Bauska</em>, Latvia, VI), 1670 (<em>Pärnu</em>, Estonia, VI), 1821 (<em>Koknese</em>, Latvia, VI), 1823 (<em>Võrtsjärv</em>, Estonia, VI), 1857 (<em>Irbe</em>, Latvia, VI), 1896 (<em>Jelgava</em>, Latvia, V), and modern earthquakes occurred on 10/25/1976 (<em>Osmussaar</em>, Estonia, M 4.7), 09/21/2004 (<em>Kaliningrad</em> region, Russia, Mw 5.2).</p><p>The study of slow (tectonic creep) and fast (earthquakes) deformations is practical importance in EBR for safety of energy facilities - <em>Plavinas</em> HPP, <em>Baltic</em> (Kaliningrad region of Russia) NPP and <em>Ostrovets</em> (Belarus) NPP.</p><p>In the central part of the territory of Latvia, signs of geodynamic activity of the Earth's crust have been identified. A characteristic feature is the trans-regional <em>Olaine-Inčukalns</em> tectonic fault, which crosses the Riga agglomeration. The fault is traced in the <em>Caledonian</em> structural complex.</p><p>Previous studies on seismic hazard assessment in Latvia (Safronovs & Nikulins, 1999; Nikulins, 2011) were based on combination of seismic, geophysical, geodetic and geological data. These studies made it possible to assess the seismotectonic potential of the Earth's crust, parameters of seismogenic zones and to state a very low seismic activity.</p><p>A sparse seismic network and poor seismic-geological conditions affect the effectiveness of seismological monitoring in EBR. To understand of driving mechanisms for earthquakes, results of remote sensing (<em>Persistent Scatterer Interferometry - PSI</em>) of surface (1992 - 2000), studies of radon anomalies (2014), and macroseismic data (2010) were used.</p><p><em>PSI</em> method made it possible to reveal the anomalous vertical velocity (25.4 mm/year) of opposite sides of fault, adjacent to the <em>Olaine-Inčukalns</em> fault in the southwest of Riga. The average vertical velocity does not exceed 1.03 mm/year. The study of the radon field in northeast of the <em>Olaine-Inčukalns</em> fault revealed an intense (140000 Bq/m<sup>3</sup>) radon anomaly (Nikulins, 2014).</p><p>In addition, on 22.11.2010, population of Riga and its environs felt shaking. Mechanism of the <em>Olaine-Inčukalns</em> fault is predominately <em>thrust faulting</em> with a <em>strike-slip</em> component, whereas mechanisms of most other faults in Latvia are <em>normal faulting</em> type.</p><p>These signs indicate the activation of the <em>Olaine-Inčukalns</em> tectonic fault. Thus, on the EBR, under conditions of slow deformation of the Earth's crust, a comprehensive analysis of various geological, geophysical and deformation parameters has justified itself.<br><br></p><p>Literature</p><p>Nikulins V., 2014. <em>Geodynamic Hazard Factors of Latvia: Experimental data and Computational Analysis</em>. Baltic Journal of Modern Computing, 7 (1), 151 – 170.</p><p>Safronovs O.N., Nikulins V.G., 1999. <em>General seismic zoning of Latvia</em>. Latvian geology news, 6, 30 - 35. (In Latvian).</p><p>Nikulin V., 2011. <em>Assessment of the seismic hazard in Latvia. Version of 2007 year</em>. RTU science articles. Materials Science and Applied Chemistry, 1 (24), 110 – 115.</p>

СПОСОБ ГЕОТЕХНИЧЕСКОГО МОНИТОРИНГА ПОРОД ТАШТУНСКОГО РАЗЛОМА ЮГО-ЗАПАДНОГО БОРТА КАДЖАРАНСКОГО КАРЬЕРА

A method has been suggested for geotechnical monitoring of tectonic fault rock mass of the south-west wall in Qajaran open-pit mine by applying the pseudo-static method of CPTu (Cone Penetration Test with in-situ pore water pressure measurements) which gives an opportunity to define the root parameters of soils such as: pore water pressure, unit weight, drained and undrained shear strength. The versatile in-situ CPTu methods allow to profile simultaneously the geotechnical properties of each soil strata with permanent penetrating speed, and also while using the SCPTu (Seismic Cone Penetration Test with in-situ pore water pressure measurements) method, as well as determine horizontal and shear seismic wave velocities from the given geomechanical environment. At that, it also becomes possible to pull out independently intact samples from tectonic-fault-soils for future laboratory testing. Two different approaches for geomechanical proposition of the south-west wall stability of Qajaran open-pit mine based on the limit equilibrium theory and outputs from the proposed in-situ geotechnical seismic monitoring (SCPTu) have been analysed. The difference of the results from the two analyzed approaches (USA vs ESA) was about 8 to 10% in estimating the slope stability. Based on the analyzed results of the stability of the south-west wall of Qajaran open-pit mine, it is recommended to apply undrained strength analysis for undrained tectonic-fault soils (USA – Undrained Strength Analysis) instead of the effective drained strength analysis (ESA – Effective Strength Analysis) for drained rocks by taking into account the developed excess pore water pressure when saturated clayey soils sheared in undrained conditions.

Ecogenetic monitoring of ionizing radiation for radon-hazardous territories

This work is devoted to studying the alpha activity distribution of natural radionuclides in boarding schools located near zones of tectonic faults. There are many tectonic faults in the Almaty and this is the basis for referring the southern capital of Kazakhstan to the radon-hazardous territories. As a result of radiometric measurements a 2D-topology of the alpha-radiation flux density distribution from the distance to the tectonic fault was found. Based on the measurements results the coefficient of radon concentration from the distance to the tectonic rupture was found. Using the obtained pattern, it is possible to plot the dependence of volumetric alpha activity for other schools, if their distances from the tectonic fault are known. In addition, interest in biomedical and ecogenetic effects of radon and its decay products has grown considerably in the last few years. These effects have been investigated in biotests on Drosophila’s two systems. It was found that alpha-particles, with the help of which the situation in radon-hazardous territories was simulated, possess mutagenic influence manifested mainly in formation of morphoses or deformities.

On the Genesis of Radon Anomalies in the Tectonic Fault Zones

As a result of almost three-year observations conducted in the fault zone in the Beshtau magmatic massif area (Caucasian Mineral Waters), anomalous seasonal fluctuations in radon exhalation rate were registered. Seasonal fluctuations are characterized by highs in summer and lows in winter. Summer values reached 23800 mBq/(m2s), while in winter the radon exhalation rate decreased to 40 mBq/(m2s). Radon exhalation rate in the fault zone shows a clear direct correlation with air temperature. The rise of radon levels in spring and fall in autumn are timed to the moments when the temperature of the atmospheric air becomes, respectively, above and below the temperature of the rock massif. It is established that seasonal fluctuations of radon levels are caused by changes in the direction of convective radon transport in the fractured zones. The obtained data suggest that the formation of seasonal radon anomalies in the fault zones is due to the circulation of atmospheric air in permeable zones of the rock massif, which occurs due to the temperature difference between the massif and the atmosphere.

Geological Map Of The Debussy Quadrangle of The Planet Mercury

<p>Geological mapping of Mercury is crucial to build an understanding of the history of the planet and to set the context for observations made by the recently launched BepiColombo mission when it begins science operations in orbit around Mercury in 2026. I am mapping the geology of the Debussy quadrangle (approximately 1/15th of the planet) as part of a pan-Europe program to map the entire planet at a scale of 1:3M using data from NASA’s MESSENGER mission. This will be the first high-resolution map of this part of Mercury. The mapped area includes the Rembrandt impact basin, the second largest on the planet, Enterprise Rupees, the longest tectonic fault as well as several explosive volcanic vents and terrains of different ages. Mapping began in October 2017 using ArcGIS software. The mapping follows the EU Plan map standards and USGS guidelines with linework drawn at 1:300k. Craters larger than 5 km have been outlined. Ejecta, where observed, is being traced for craters larger than 20 km and classified. Craters are classified based on crater degradation using both 3 class and 5 class schemes to enable comparison between historical and current maps of the rest of the planet and to enable placing features and units into context. A separate mapping layer for superficial shows the most recent modifications to Mercury’s surface, including volcanic deposits and impact craters. I present the map and with working geological interpretation.</p>

Response of the building with a stiffening core during an earthquake of February 02, 2018 in the territory of a metropolis

Earthquakes give rise to a significant number of problems that affect environmental, seismic, and economic risks forthelocalsand construction sites. For the first time in the last 40 years, another local zero depth earthquake was registered in the territory of the city of Almaty. In terms of intensity, this was a 3-4-point earthquake. At 100 meters from the tectonic fault, there is a 16-storey building with a stiffening core and an engineering seismometric service station. With the use of AT 1105 sensors and a PCM-8 recorder, instrumental records of accelerations in the basement and on the roof of the building were recorded, and spectral β curves were constructed. The effective duration of the seismic impact in the basement of the building was quite significant, 47-56 seconds. There is undoubtedly an increase in the intensity of local earthquakes compared to 2007-2014. It was found that at the basement level the value of the vertical component is significantly less than the horizontal one. It is assumed that the abnormally high values of acceleration in the horizontal plane are a consequence of the presence of a tectonic fault near the building. Instrumental records of acceleration (accelerograms) can be used in calculations of both the seismic resistance of an object and the assessment of environmental, social, economic, and non-economic risks.

Characterization of the leakage problem in Salhab earthen dam using electrical resistivity tomography and SP measurements, Syria

The earthen dam of Salhab is located in the southern margins of Al-Ghab plain at 3–4km of Salhab town northern-west of Syria. The dam consists of two separated embankments: the main one extends east-west along a distance of 895 m with 14.5 m height, while the second embankment towards northwest-southeast over a distance of 510 m and 11 m of height. The dam crest has a constant topographic elevation of 220 m above sea level (a.s.l). Electrical Resistivity Tomography surveys (ERT) combined with a Self-Potential measurements (SP), were implemented at the upstream and at the top of the main and the secondary embankments of the dam in order to identify the possible leakage zones under the dam’s body. The interpretation of the ERT sections and the SP measurements, carried out at the upstream side, revealed a distinct zone of leakage extending along the beginning and the end parts under the main embankment. Moreover, many punctual anomalous spots of low resistivity values were recognized within the dam’s clay core. One of those spots was confirmed by the implementation of a detailed ERT profile and by a piezometric borehole drilled at the top of the dam. Whereas, the clay core of the secondary embankment seems relatively coherent and homogeneous as well as a trace of a tectonic fault was identified under the end part of the embankment body but no manifestations of leakage were observed under and behind the secondary dam body.