MSK-64 Scale Research Articles

EXPERIMENTAL DETERMINATION OF DYNAMIC COEFFICIENT OF AMONTON-COULOMB DRY FRICTION

The purpose of the study is to experimentally determine the dynamic coefficient of dry friction between different materials under vibrations due to the initial deflection. The principle of dry friction between the grillage and the foundation is used for the seismic isolation of buildings and structures. A measuring complex with corresponding strain-gauge measuring channels was prepared on the laboratory one-component shaking stand to record the relative and absolute displacements of two-mass systems. A theoretical solution to this nonlinear problem was obtained with the additional use of a special logical algorithm to determine the direction of the dry friction force between two masses. The value of the dynamic coefficient of dry friction was determined by comparing the numerical solution to the problem with experimental records by selecting the value of the dry friction coefficient. The values of the mass of rubbing elements with the surface treatment of the steel-on-steel contact and a separate option with lubrication of the contact surface with fluoroplastic 4-on-fluoroplastic 4 gaskets were changed in the experiment. The maximum velocity of the platform in experiments corresponds to a 9-point earthquake on the MSK-64 scale.

Deterministic ground motion modeling with target earthquakes and site effects in eastern Azerbaijan

In the context of assessing seismic hazard, accurately predicting ground motion stands out as a crucial task. Achieving precision in ground motion modeling proves valuable in revealing the actual pattern, even when faced with insufficient data on soil structure, provided there is precise information about the seismic source. This study introduces a methodology for calculating local- and near-field ground motion, expressed in peak ground acceleration (PGA) and intensity values. The deterministic approach is employed, incorporating source characteristics and one-dimensional (1D) site effects. For the chosen test area, the Ismayilli-Shamakhi region on the southeastern slope of the Greater Caucasus in Azerbaijan, two seismic scenarios are investigated: the 1902 Shamakhi earthquake (magnitude M = 6.8) and the November 25, 2000 Baku-Caspian earthquake (two shocks with moment magnitude Mw = 6.08 and 6.18). Different soil types are considered to validate the proposed methodological procedures. The analysis involves the computation of peak ground acceleration motion for two scenario earthquakes: a local-field event with M = 6.8 and a near-field event with Mw = 6.5, representing the average magnitude of the 2000 Baku-Caspian earthquake. The computed peak ground acceleration values are then used to derive intensities. Notably, the 1902 Shamakhi earthquake and the 2000 Baku-Caspian earthquake exhibit similar trends on surface PGA values. The local-field scenario estimates PGA values ranging from 77 to 328 gal, corresponding to MSK-64 scale intensity levels of VII-IX. The near-field scenario, with PGA values ranging from 28 to 62 gal, aligns with MSK-64 intensity levels of VI–VII. In the final assessment, the amplification factor in the study area varies between 0.55 and 0.83. The seismic hazard level is identified as high in the southern and southeastern regions, particularly in areas with soft shallow and medium-depth soils, indicating a high potential for ground motion amplification.

Analysis of the dynamic response of a base isolated building during an earthquake with an intensity of 7 points on the MSK-64 scale

Introduction. The problem is considered and the relevance of studying the behavior of buildings and structures with seismic isolation systems using lead rubber bearing under real seismic impact, as well as assessing their technical condition after the earthquake, is emphasized. The experience of studying the behavior of base isolated buildings under real seismic impact abroad and in Russia is given.
 Materials and methods. The dynamic parameters seismic isolation of a reinforced concrete building using lead rubber bearing are investigated. Registration of seismic vibrations of the building was performed by a stationary station for dynamic monitoring. The results of processing the records were obtained based on the interpretation of monitoring data, including harmonic analysis, determination of the power spectral density, as well as the application of wavelet transform methods.
 Results. The results of dynamic monitoring of a base isolated building of a sea terminal located in Petropavlovsk-Kamchatsky city during an earthquake of 04/03/2023 with a magnitude of Mw =6.6 and an intensity at the site of the building equal to 7 points on the MSK-64 scale are presented. An analysis of the response and dynamic parameters of the building was performed, as well as a visual inspection of structures, as well as the building's seismic isolation systems.
 Conclusions. Analysis of the dynamic monitoring results made it possible to identify the natural vibration frequencies of the building, as well as to trace their changes during seismic impact. The maximum displacements of the building indicate minor shear deformations of the lead rubber bearing corresponding to the zone of their elastic operation. Both the rigidity of lead rubber bearing and the dynamic parameters of the building (frequencies (periods) of natural vibrations and the logarithmic damping decrement of the building) change depending on the intensity of the seismic impact and the shear deformation of the bearings, respectively. After the earthquake, widespread cracks and peeling of the plaster wall were observed with partial exposure of the layer of insulating material in the zone of filling with elastic elements the gaps between the strapping beams of the seismic isolation system and the structures of the building partitions at the level of the seismic isolating layer, which did not affect the operational reliability of the building. The study presented in this article shows that with the help of dynamic monitoring of buildings and structures, one can get a more complete and detailed understanding of their dynamic behavior, identify damage in the structural system of a building, and detect their undesirable or specific reactions that could not be taken into account when designing.

Seismic events in the Sverdlovsk region for the period 1788–2022

Introduction. Sverdlovsk region is a major industrial center. There are mining enterprises, chemical plants, reservoirs, and high-capacity power plants. These objects are located close to large settlements. Currently, about 400 seismic events are recorded annually in the region. To ensure the seismic safety of objects of increased responsibility and especially important construction objects, it is necessary to carry out studies on detailed seismic zoning of the territory under consideration. The results of this work are the first stage of these studies. Research theory. For the first time, a consolidated unified catalog of seismic events that occurred on the territory of the Sverdlovsk region was compiled. Historical and instrumental catalog data for the period 1788–2022 and data from instrumental records of local seismic events recorded by temporary, mobile stations of the Institute of Geophysics Ural Branch of the Russian Academy of Sciences (IGF UB RAS) served as the basis. served as the basis. Results. Most of the recorded events are technogenic. Mostly these are industrial explosions and rock burst. These seismic events are recorded in the area of the following cities: Asbest, Ekaterinburg, Revda, Nizhny Tagil, Kushva, Kachkanar, Karpinsk, Severouralsk. Tectonic earthquakes have also been repeatedly recorded in the Sverdlovsk region. Most of them are not felt by people. Earthquakes with a magnitude greater than 4.0 have macroseismic manifestations. The strongest earthquake is 08.17.1914 (MS= 5.0, epicenter coordinates 57.09° N, 59.8° E). The intensity of the earthquake at the epicenter was 6.0 on the MSK-64 scale. The results of this work will serve as a basis for further determination of the parameters of the seismic regime of the study area.

SEISMICITY of the NORTHERN CAUCASUS in 2018–2019

Seismic monitoring of the territory of the North Caucasus in 2018–2019 was carried our by a seismic network of 66 stations. All stations were digitally equipped. The seismic network provided representative registration of earthquakes with KR≥7.0 in most of the territory, in its central (including the Greater Sochi region) and eastern parts – with KR≥6.0, and in some local zones – with KP≥5.5. In general, 6874 earthquakes have been recorded in the region and its environs. 59 earthquakes were felt in the Caucasus settlements, 26 of them occurred in the North Caucasus region. The maximum shaking intensity Imax=6 by the MSK-64 scale was noted from the Zagatala earthquake of June 5, 2018 with KR=14.1 occurred in the territory of the Azerbaijan and from Buynak-II earthquake of May 24, 2019 with KR=11.5 in Dagestan near the Chirkey reservoir. On the territory of Ossetia and Ingushetia (Tersko-Caspian forward trough) two earthquakes, Zamankul and Yandar, were felt with intensity up to I=5. A doublet EQ felt up to I=3–4 was recorded on November 24, 2018 (KR=10.3) and November 25, 2018 (KR=10.5) in the West Kuban marginal trough. In accordance with the seismicity level scale "SOUS-09", seismicity of the North Caucasus in 2018–2019 is set as a "background average" for the observation period from 1962 to 2019.

Institute Teploelektroproyekt - 105 years in the service of the country's energy industry

The article is devoted to the 105th anniversary of Institute Teploelektroproyekt. Thermal power plants built according to the Institute's designs over the past twenty years, with installed combined-cycle and steam-power units running on gas and coal, are presented. The article describes the current environment of the institute's activities, the limitations of centralized financing of projects, the withdrawal from the market of power equipment of a number of foreign manufacturers of gas turbines due to sanctions, the adjustment of business plans of traditional customers of energy projects. The Institute actively accepts challenges, works with Russian manufacturers of gas turbine units, capitalizes on the accumulated experience of designing combined-cycle power plants (CCPP). An experience of construction and operation of the first stage of Sakhalinskaya SDPP-2 operating on coal, with a seismicity of the site at 9 points on the MSK scale on the coast of the Tatar Strait, is presented. During the time of operation of the station, the Sakhalin coal was found to be extremely viscous, which is associated with the presence of bentonite in its mineral part. The measures taken to partially reconstruct the fuel supply path led to a significant improvement in the operation of the path. The Institute-designed Svobodnenskaya thermal power plant (TPP) was put into operation, generating electricity and steam to provide consumers of the Amur Gas Processing Plant. Gas fuel is supplied from the main gas pipeline Power of Siberia-1. This implemented project is one of the examples of choosing a gas-fired steam turbine unit in favor of CCGT. The project Boiler House as Part of Ethane-Containing Gas-Processing Combine in the settlement of Ust-Luga on the Baltic Sea coast is unique as an example of the full integration of thermal power plant into a large industrial enterprise in order to solve the problem of minimizing the possible consequences of a major accident at the combine. The design of combined-cycle power plants of Novocherkasskaya SDPP and Artemovskaya CCPP-2 on the basis of domestically produced GTUs with a unit power of 110 and 160 MW, construction projects of new power units of Norilskaya CCPP-3 and Yakutskaya SDPP-2 for permafrost conditions are close to completion. The projects for the successive modernization of the Kirishskaya SDPP and Surgutskaya SDPP-1 power units with the replacement of steam turbine units are at the stages of designing and implementation. Institute Teploelektroproyekt is, as before, holding one of the leading positions among the design organizations of the industry, making a significant contribution to the development of the country’s energy industry.

Macroseismic Study of 4th January 2016, Manipur Earthquake, and its Implications

Abstract An earthquake of magnitude 6.7 M (Latitude 24.834N; Longitude 93.656E) on the Richter scale rocked in the Noney area, Tamenglong district, Manipur on 4th January 2016. The shock was strongly felt in most parts of the Northeastern states of India viz. Manipur, Nagaland, Meghalaya, Assam, and its neighboring countries Myanmar and Bangladesh. Macroseismic study was conducted to assess the intensity of ground motion and related damages caused by the earthquake. The damage incidences were mainly reported in structures constructed over the alluvial fill material. Deformations and development of ground fissures were observed in the epicentral tracts of Manipur and liquefaction phenomenon was observed in the Silchar area Assam. The study revealed that higher damage was confined to the area around Noney, Kabuikhullen, Nungba, Leimakhong, and Imphal valley areas in Manipur and Silchar town areas in Assam. Based on field observation, the degree of damage to building structures, and data gathered from the local population using the standard questionnaire, different intensity values were assigned to each locality. Isoseismal map was prepared by drawing the boundaries between different intensity areas at MSK-64 scale. The result indicates that the intensity was within the range of IV to VII. The maximum intensity was found VII in parts of Imphal, Tamenglong, and Silchar and very close to the epicentral tract area of Noney; and lowest intensity IV was observed in other parts of the northeastern states around Dimapur and Kohima in Nagaland state. The location of the epicenter of main shock (M 6.7) was at the intersection of the two major lineaments trending to ENE-WSW and NW-SE. The trend and shape of isoseismals drawn on seismotectonic/geological maps are elliptical along ENE-WSW direction and are found more closely spaced in the north and southern parts of the affected area. The elliptical nature of the isoseismals indicates that this seismic event was caused by movement along a linear surface. Furthermore, the orientation of elliptical isoseismals with a major axis trend in an ENE-WSW direction is almost parallel to the ENE-WSW trend of major lineament/fault in the area. As a result, the ENE-WSW lineament/fault trend appears to be the causative fault for this quake. In addition, one of the nodal plane (NP2) striking 83°, with dip 81° and slip (rake) 38° obtained from fault plane solution USGS shows a similar trend to the direction of generated elliptical isoseismals pattern confirming the event ocurred along a major tectonic lineament in a strike-slip mechanism.

A POSSIBLE IMPACT OF SCENARIO EARTHQUAKES IN THE CAUCASIAN MINERAL WATERS ZONE

This paper analyzes a possible impact of scenario earthquakes in the zones of high seismic hazard in order to justify measures for ensuring population safety by the example of the southern Stavropol krai area. Over the past twenty years, the Central CisCaucasus region shows elevated seismicity based on the data recorded by the Geophysical Survey RAS network, reporting the occurrence of seismic events within a wide range of magnitudes, М≥1. One of the last felt events with mb = 4.4 occurred in the studied area on April 1, 2023, producing shaking intensity of 3 to 4 grades on the MSK-64 scale in large resort cities of the region. The parameters for the scenario events are based on the results of detailed seismic zoning (DSZ) and review seismic zoning (RSZ-2016) obtained by the Schmidt Institute of Physics of the Earth RAS. The Extremum system was used to assess felt effects in resort centers located in the southern Stavropol krai. We analyzed the influence of seismic intensity propagation and the parameters of macroseismic field equation on the assessed impact of the scenario earthquakes. Special attention was paid to the depths of strong and moderate events in the considered area of the Northern Caucasus and to the orientation of macroseismic isoseismals. Pre-calibration of the Extremum system loss models is recommended. Estimates of possible simulated damage due to scenario earthquakes with M=6.0 and M = 5.0 for individual large resort cities of the Kavminvody zone are given. The results can be used in the development of both preventive measures and response plans in case of possible events in the region.

Study of work of PVC membranes for engineering waterproofing under increased seismic conditions

Objective. At present, increased requirements are imposed on waterproofing materials used in seismic hazard zones. The aim of the study is to assess the possibility of using LOGICBASE™ polymer membranes in regions of increased seismic activity in the Russian Federation.Method. The mechanism of operation of polymeric membranes in foundation structures under conditions of constant displacement and friction is considered. Experiments were carried out to determine the coefficient of friction according to the method of state standards on a tensile testing machine MIRK-1000K. Samples of a round shape made of polymeric membranes were studied on a special multiaxial stretching device in accordance with the requirements of state standards.Result. Multiaxial tensile testing of LOGICBASE™ V-SL polymeric membranes revealed that the maximum tensile strength of the samples was 6948.22 kPa (~ 6.95 MPa), and the elongation of the samples at break was 113.89%. The coefficient of friction in the system "polymer waterproofing material - concrete structure" was determined under conditions of increased seismic activity according to the MSK-64 scale.Conclusion. According to the studies, it was concluded that PVC membranes for engineering waterproofing can be used in construction areas with seismicity up to 9 points inclusive on the MSK-64 scale.

Shear oscillations of bridge on sliding foundation during earthquake

The article investigates the vibration of the railway bridge on the sliding foundation with dry friction under the action of real earthquake records at the intensity of 7, 8, 9, and over 9 on the MSK-64 scale. Dynamic dry friction problems are non-linear since each slip's start and end times are determined during the problem-solving process; they depend on many design parameters and external influences. The simplified model of vertical and shear deformation of the bridge is proposed as oscillating intermediate support with the mass of the span connected to the girth rail by a rubber bearing part. In this case, all elements in the structural model are connected to each other, taking into account eccentricities. The finite element method discretizes the coordinate variables and the Newmark time method with matrices built at each step. Structural vibrations are studied based on four real earthquake records. It is shown that using a sliding foundation can significantly reduce the shear forces in the bridge supports depending on the structure mass, the dry friction coefficient, and the nature of the seismic effect.

SEISMICITY of the NORTHERN CAUCASUS in 2016–2017

Seismic monitoring in the region was produced by a seismic network of 58 stations in 2016 and 60 stations in 2017. All stations were digitally equipped. The seismic network provided representative registration of earthquakes with KR≥7.0 in most of the region, in the central (including the Greater Sochi region) and eastern parts of the region – with KR≥6.0, and in some local zones with KR≥5.5. In general, 5594 earthquakes have been recorded in the region and its environs. 66 earthquakes were felt in the Caucasus settlements, 24 of them occurred in the North Caucasus region. The maximum shaking intensity, Imax=6 by the MSK-64 scale, was noted at the March 6, 2017 earthquake with KR=10.9 occurred in the territory of the Chechen Republic. August 7, 2016 earthquake in the Azov Sea, not far from Mariupol, was felt up to I=5. The strongest and most perceptible earthquakes were registered in Dagestan (in the tectonic regions of the Greater Caucasus and the Dagestan wedge). In accordance with the seismicity level scale "SOUS-09", seismicity of the North Caucasus in 2016–2017 is set as a "background average" for the observation period from 1962 to 2017.

KRILLON EARTHQUAKE on April 23, 2017 with Mw=5.1, I0=5 (Sakhalin Island)

On April 23, 2017 at 06h 37m UTC, an earthquake with a magnitude of Mw=5.1 was registered in the foothills of the Yuzhno-Kamyshovy Ridge of the Krillon Peninsula. This earthquake was the strongest on Sakhalin Island in 2017. The earthquake parameters were determined according to the data of the Sakhalin branch of the Geophysical Survey RAS regional network with the use of data from the global IRIS Network (GSN) and stations of Hokkaido University. The obtained earthquake parameters according to the regional network are consistent with the data of international seismological centers. The maximum intensity of shaking from the earthquake on April 23, 2017 in the settlements of Southern Sakhalin was I=4 on the MSK-64 scale, on the Hokkaido Island – I=II on the JMA scale. The displacement in the earthquake foci was realized under conditions of near-horizontal sublatitudinal compression. The type of seismic dislocation is a reverse fault. The use of data from the seismic stations of the local network of Southern Sakhalin allowed analyzing the seismic regime in the epicentral zone of the Krillon earthquake.

ONOR EARTHQUAKE on August 14, 2016, Mw=5.8 (Sakhalin Island)

On August 14, 2016 at 11h15m UTS there was a strong earthquake with Mw=5.8 in the central part of the Sakhalin Island, which felt in nearby settlements with an intensity of up to Ii=5–6 by the MSK-64 scale. The greatest intensity of shaking was recorded in the village of Onor, closest to the epicenter. Within 2 weeks after the earthquake, more than 130 aftershocks were registered by regional seismic stations. The aftershock zone is extended in the NW-SE direction. Subhorizontal compressional stresses of the NE-SW orientation were realized in the earthquake foci. The type of movement in the source is a reverse-fault with a slight strike-slip component. The fault plane with the south-western dip direction was adopted as an operational. The earthquake source belongs to one of the secondary structures of the Central Sakhalin oblique-reverse fault, which cuts through a section of the Western Sakhalin Mountains in the direction of the western coast. The active block of the fault is the eastern wing, underthrusting under the western one. Based on the results of the macroseismic inspection, theoretical isoseists are calculated and constructed. Such a rare strong earthquake aroused wide interest among specialists and allowed them to test several new methods and technical solutions, as well as obtain new information about the seismicity and tectonics of the Sakhalin region. This article presents a comprehensive overview of seismological information on this earthquake, mainly based on the results of earlier publications.

MARIUPOL EARTHQUAKE on August 7, 2016 with Мw=4.6, I0=5 on the NORTHWESTERN COAST of the SEA of AZOV

The instrumental and macroseismic data on the earthquake of August 7, 2016 with Mw=4.6, which occurred near the city of Mariupol (Ukraine) and was felt in 47 settlements at distances up to 458 km from the epicenter with an intensity of 2 to 5 at MSK-64 scale , are presented. The earthquake occurred in the area of the North Azov fault at the southern border of the East European platform. The spatial distribution of macroseismic data made it possible to construct a map of isoseists of Ii=3 and 4. The focal mechanism is constructed and a strike-slip motion type in the focus is determined.

UGLYA-IV EARTHQUAKE on June 6, 2017 with KR=9.8, ML=2.7, І0=5 (Ukraine, Transcarpathia)

On June 6, 2017 at 17h27m in the mountains north of Uglya of the Tyachiv district of the Transcarpathian region, at a depth of h=5 km, a significant earthquake with energy class KR=9.8 and local magnitude ML=2.7 occurred. The earthquake was processed by records of 16 seismic stations of the Carpathian network. Immediately after the earthquake, information on its impact was collected through a telephone survey in 23 settlements located at distances of 5–30 km from the epicenter. As a result of processing the survey data from 23 settlements, an isoseismal map of the earthquake was constructed. The epicenter of the earthquake was located in an unpopulated mountainous area, where a calculated intensity was I0=5 by the MSK-64 scale. In the epicentral zone, it was felt with an intensity of 4–5 in 3 settlements: Prygid, Velikaya Ugolka and Fontynasy. According to a comparison with the map of the fault structures of the Solotvinskaya depression of the Transcarpathian trough and adjacent territories, it is clear that this earthquake is located in the zone between the Chernogolovsky and the Penin faults, where a lot of fault structures are noted, including an unclear morphology.

SEISMICITY of KAMCHATKA and COMMANDER ISLANDS in 2016–2017

The seismicity review of Kamchatka and surrounding territories for 2016–2017 is given. In the Kamchatka earthquake catalogue, the minimum local magnitude of completeness is MLmin=4.0, and for earth-quakes with h≥350 km under the Okhotsk sea MLmin=4.3. The Kamchatka catalogue of earthquakes with ML=3.6–7.3 for 2016–2017, published in the Appendix to this article, includes 2898 events. 191 earthquakes of the catalogue were felt in Kamchatka and surrounding areas with seismic intensity I=2–6 according to the MSK-64 scale. For all events with ML≥5.0 that occurred in 2016–2017 within the area of responsibility of Kamchatka branch of Geophysical Survey RAS, an attempt to calculate the seismic moment tensor (SMT) was made. There are 109 such events in the regional catalogue. For 102 earthquakes the SMT and depth of the equivalent point source were calculated. The calculations were performed for the SMT double-couple model using a nonlinear algorithm. The level of seismicity according to the “SOUS'09” scale in 2016 corresponds to the “background increased”, for 2017 it is also the “background increased”, but within the assessment accuracy – “high”. In 2016–2017 within the Kamchatka branch area of responsibility, an atypical pattern of the location of earthquake epicenters was observed due to the occurrence of two strong events – the Near Aleutian (Mw=7.8, July 17, 2017) and South Ozernovsky (Mw=6.6, March 29, 2017) earthquakes and their aftershock processes.

Neotectonics and seismicity of the Urals

Introduction. The Ural submeridional mountain belt is an epipaleozoic orogen rejuvenated in the contemporary period (in the Neogene-Quaternary period in the last 20–30 million years). In the pre-Paleozoic era, the Urals developed as a submeridional upland, presumably as a result of the interaction (clash) between the East European and West Siberian plates. In the Mesozoic and Cenozoic eras, the Urals developed as a submeridional upland. As a result, the Ural Paleozoic orogen was largely (almost completely) destroyed by weathering, but in the second half of the Cenozoic time it was rejuvenated and experienced some growth again. The reason for the rejuvenation of the Urals could be the subhorizontal compression of the Urals crust between the East European (EEP) and West Siberian (WSP) plates, which occurred in the contemporary period (in the last 20–30 million years). The epicenters of contemporary Ural sensible earthquakes are localized in the East European Craton bordering the Urals along the boundaries of the Ufa obduction of the EEP. The intensity of Ural earthquakes ranges from 3–4 to 5–6 according to MSK-64 scale, and their magnitude is estimated in the range from 2.0 to 6.0–6.5. Research objective is to assess the seismicity and seismic activity of the Urals in the contemporary period and the relationship between Ural sensible earthquake epicenters and its rejuvenated tectonic structures. Methods of research. The spacing of sensible earthquake epicenters in the Urals relative to tectonic structures of different age was estimated by comparing the corresponding geological and tectonic schemes of the Urals. Results. The analysis showed that the epicenters of sensible earthquakes are located mainly along the periphery of the Ufa obduction of the EEP, which interacts with the Ural orogen. Most of the epicenters are located in the northeastern boundary of the Ufa obduction of the EEP. Earthquake epicenters are located both within the Ural orogen (in the zone of geodynamic influence of the Serov-Mauk regional submeridional fault), and within the eastern edge of the East European Craton, in the trough of the western piedmont of the Ural Mountains and adjacent areas.

Study of seismic risk perception in Craiova municipality

This study aims to evaluate the perception of the population regarding the potential danger generated by earthquakes in Craiova. Although it is located at a significant distance from the main seismic region of Romania (i.e. about 400 km from Vrancea), Craiova Municipality is still in an area with seismic risk according to the National Institute of Research and Development for Earth Physics (NIEP/INFP in Romanian). Regarding the seismic area in Romania, Craiova is classified at an 8 level on the MSK scale (according to Law no. 575/2001); moreover, the strong earthquakes produced in the last half-century had some notable effects on the territory of the municipality. In Craiova, the deficiencies concerning the anti-seismic education, the condition of the old constructions that are still used, the non-conforming structural changes brought to the buildings, etc. may increase the risk of an earthquake of medium and high magnitude. The present paper is based on the random sampling of 120 people from Craiova Municipality regarding their perception of earthquakes. It was found that half of them experienced at least one major earthquake (particularly that of 1977, which caused significant property damage and fatalities). The personal experience of such an earthquake or the participation in the simulative exercises of an earthquake in the city determines some of the respondents consider that they have learned how to behave during an earthquake. On the other hand, some of the respondents (especially the single or retired ones) expressed their lack of trust in the help they could receive during an earthquake.

Research into landslide processes in the coastal zone of the Takhtakorpureservoir using vertical electrical sounding method (the southeastern slope of the Great Caucasus)

Landslide-prone areas on the coastal zone of the downstream of the Takhtakorpu reservoir located on the arid-hilly part of the southeastern slope of the Great Caucasus mountain system (Azerbaijan) were investigated using vertical electrical sounding (VES) method. The entire research area is geologically active. It is complicated by seismicity (with an intensity of 8—9 points on the MSK-64 scale), vertical (uplift of the Earth’s crust about +6 mm/year) and horizontal (4 ± 1 mm/year, generally north-north-east) movements, landslides (in more than 5 centers) as well as the Gaynarja mud volcano, in the form of hill ≥100 m in diameter with griffins. Tectonically, the mud volcano is timed to the consolidated part of the anticline of the same name, which currently is located in the right-bank zone, closer to the water of the Takhtakorpu reservoir. Therefore, the erupted products of the mud volcano come into contact with the aquatic environment. The geological structure of the territory is dominated by rocks of the Pliocene Productive Stratum (N2). With respect to lithology, they consist of clays and argillaceous rocks. Groundwater occurs sporadically, with a total salinity of 7 g/l and a filtration coefficient of 4 m/day. Geological sections of the area were studied to a depth of 40 m, the thickness and composition of individual layers of rocks were described. 3D models of the study area were developed completely in an arbitrary cut and also along the X, Y and Z axes. It was revealed that the layers composing the geological section of the region are subject to the impact of plicative dislocations due to the geodynamic processes. It is assumed that landslides in the study area are mainly formed at the contact of eluvial-deluvial deposits with bedrocks. One of the main reasons for the formation of landslide phenomena, apparently, is also associated with the steepness of the slopes and their constituent rocks, which absorbing atmospheric precipitation become waterlogged. The depths of the assumed slip planes in individual landslide blocks were revealed and the thickness and direction of the landslide body were determined.

ОЦЕНКА СЕЙСМИЧЕСКОЙ РАЗЖИЖАЕМОСТИ ГРУНТОВ ЮЖНОЙ ЧАСТИ БАРЕНЦЕВА МОРЯ

The article presents analysis of results of seismic liquefaction assessment of soils distributed in the southern part of the Barents Sea. Studies of the tendency of seabed soils to liquefaction were carried out as part of the engineering-geological surveys for the construction of production facilities of the Shtokman gas-condensate field (ShGKF). A review of similar studies carried out in seismically hazardous areas of the Black Sea, the Sea of Azov and the Sea of Okhotsk is given. It is noted that formation of seismic deformations caused by liquefaction of soils is very dangerous for oil and gas production facilities both onshore and offshore. The dynamic stability of soils in the southern area of the Barents Sea was performed based on the results of cone penetration testing and calculation of seismic liquefaction potential. It is shown that the studied clay and sandy soils of the foundations of the ShGKF project facilities, on the basis of cone penetration testing, are not prone to liquefaction under the seismic loads typical for the southern part of the Barents Sea. At the same time values of seismic liquefaction potential indicate the possibility of coastal sandy soils transition to fluid state for earthquakes of 7,7 intensity according to the MSK-64 scale. It is recommended to predict the danger of liquefaction of these soils by dynamic properties laboratory determination.