Seismic Instruments最新文献

{"title":"Results of 2D Inversion of Data from Deep Electromagnetic Probing with Industrial Power Lines (FENICS Experiment)","authors":"A. N. Shevtsov,&nbsp;A. E. Hannibal,&nbsp;T. G. Korotkova,&nbsp;A. A. Skorokhodov","doi":"10.3103/S0747923922080114","DOIUrl":"10.3103/S0747923922080114","url":null,"abstract":"<p>At the stages of the FENICS experiment conducted in 2014 and 2019, unique data on deep electromagnetic sounding with grounded sections of industrial power lines were obtained at distances from 180 to 940 km from the center of the supply line to the measuring installation. The electromagnetic field components were recorded by VMTU-10 measuring equipment (VEGA, St. Petersburg). The fluctuations of the current in the supply line were recorded as a time series with a sampling rate of 1 kHz. Based on synchronous time series of the field components at the observation points and the current strength in the supply vibrator, estimates of the power spectra of the autocorrelation and cross-correlation functions of the recorded values were calculated using fast Fourier transform (FFT). The resulting spectral characteristics were used to determine the amplitudes of the field components of the source and phase shifts between them, as well as to estimate the impedance tensor components. To do this, correction factors were calculated for the ratio of the apparent resistivity values for the horizontal magnetic field component to those for the impedance and electric field. A 2D interpretation is made and estimates of the resistivity allocation at depth are obtained for two sublongitudinal and sublatitudinal profiles of the Karelia–Kola region.</p>","PeriodicalId":45174,"journal":{"name":"Seismic Instruments","volume":"58 2","pages":"S302 - S310"},"PeriodicalIF":0.9,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4831921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Efficiency of the Seismological Network of the Republic of Karelia","authors":"V. Yu. Burmin,&nbsp;I. A. Zueva","doi":"10.3103/S0747923922080060","DOIUrl":"10.3103/S0747923922080060","url":null,"abstract":"<p>To solve many geological and geophysical problems, in particular, prediction of strong earthquakes, seismic zoning, and earthquake-resistant construction, it is necessary to have reliable data on the distribution of earthquake hypocenters in the study area. In turn, the completeness of data on the distribution of earthquake hypocenters and accuracy of their determination largely depend on the efficiency of the observation system. We evaluate the efficiency of the actual network of seismological observations in Karelia, which consists of seven seismic stations. The efficiency of the seismological observation network is estimated by the minimum magnitudes of seismic events recorded in the considered region and the minimum errors in determining the main parameters (origin time and hypocentral coordinates) of the recorded events. Calculation of the minimum earthquake magnitudes for the Karelian seismological network shows that a station amplification of 30 000, the network is able to record earthquakes with a magnitude slightly less than 2, with a tendency towards a decrease in this minimum magnitude, provided that the event is recorded by at least three stations. The errors in determining earthquake epicentral coordinates in latitude δφ (km) and longitude δλ (km) do not exceed 1–2 km in the center of the network, and 6 and 11 km on the periphery, respectively. The system’s errors in determining the depths of earthquake sources <i>H</i> (km) do not exceed 5 km in the vicinity of the stations and 25 km throughout the territory of Karelia.</p>","PeriodicalId":45174,"journal":{"name":"Seismic Instruments","volume":"58 2","pages":"S247 - S257"},"PeriodicalIF":0.9,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4829861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Macroseismic Data on Earthquakes of Minusinsk Okrug, Yenisei Province, in 1841–1914","authors":"R. E. Tatevossian,&nbsp;N. G. Mokrushina","doi":"10.3103/S0747923922070118","DOIUrl":"10.3103/S0747923922070118","url":null,"abstract":"<p>Historical earthquakes of Minusinsk okrug of Yenisei Province are studied. Information in mass media and professional literature of the second half of the 1800s–early 1900s make it possible significantly to enrich the very limited knowledge on regional seismicity. Materials on six earthquakes missing in former basic macroseismic catalogs are presented, as well as original information from unknown sources on four earthquakes. As a result of the study, one can classify the territory as an area of moderate seismicity. The maximum observed intensity does not exceed 7 on the MSK-64 scale.</p>","PeriodicalId":45174,"journal":{"name":"Seismic Instruments","volume":"58 1","pages":"S25 - S41"},"PeriodicalIF":0.9,"publicationDate":"2023-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5096280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a Method for Studying the Resonance Characteristics of Soils from Spectral H/V Ratios","authors":"M. V. Rodkin,&nbsp;A. G. Bugaevskiy","doi":"10.3103/S0747923922070179","DOIUrl":"10.3103/S0747923922070179","url":null,"abstract":"<p>An improved statistical method for determining the resonance frequencies of soils from spectral <i>H/V</i> ratios is presented. The combination of developed methodological and computational techniques makes it possible to identify with high reliability the resonance frequencies of the soil sequence and fundamental frequencies of the natural vibrations of structures and their elements based on engineering seismological observations. The authors demonstrate the possibility of refining the seismic soil model of a site and compiling spatial models of the change in depths of seismic boundaries of layers of the soil sequence from the results of frequency analysis of records of microseisms and seismic events. The use of the described engineering and seismological observations and methodological techniques makes it possible to instrumentally estimate the increase in amplitudes of vibrations of structures and their individual elements at resonance frequencies and obtain a sufficiently detailed seismometric floor-by-floor description of the vibrational characteristics of buildings and structures.</p>","PeriodicalId":45174,"journal":{"name":"Seismic Instruments","volume":"58 1","pages":"S148 - S160"},"PeriodicalIF":0.9,"publicationDate":"2023-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4797936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of Seismic Hazard Assessments Obtained with the Probabilistic and Probabilistic-Deterministic Approaches for the Territory of Uzbekistan","authors":"R. S. Ibragimov,&nbsp;T. L. Ibragimova,&nbsp;M. A. Mirzaev,&nbsp;S. H. Ashurov","doi":"10.3103/S0747923922070040","DOIUrl":"10.3103/S0747923922070040","url":null,"abstract":"<p>The study compares seismic hazard assessments of the territory of Uzbekistan, obtained with the same input parameters, but using different methodological approaches: the Riznichenko approach based on the theory of macroseismic and spectral-time shaking and the classical Cornell probabilistic approach based on the full probability theorem. As seismic source models, linearly extended sources (seismogenic zones) and area sources (quasi-uniform seismological provinces) were considered. The authors used a number of their own damping dependences, established from analysis of isoseismic earthquake patterns in Central Asia, when assessing the seismic hazard of the study area in terms of macroseismic intensity, along with the Shebalin dependence, obtained from global data (<i>I</i> = 1.5<i>M</i> – 3.5 log <i>R</i> + 3). To estimate seismic hazard in engineering seismic indicators, the dependences built into the R-CRISIS software package, developed over the past 10–12 years for shallow active crust and stable regions, were used as the ground motion equation. For a 50-year seismic impact nonexceedance probability <i>P</i> = 0.90, the maximum differences in seismic hazard assessments using the two considered approaches for the entire seismically active part of the study area are ∆<i>I</i> = 0.39; for <i>P</i> = 0.95, ∆<i>I</i> = 0.54; for <i>P</i> = 0.98, ∆<i>I</i> = 0.61; and for <i>P</i> = 0.99, ∆<i>I</i> = 0.76. A similar comparison of seismic hazard assessments in the values of maximum ground motion accelerations leads to the following figures: for <i>P</i> = 0.90, ∆<i>a</i>_max = 75 cm/s²; for <i>P</i> = 0.95, ∆<i>a</i>_max = 111 cm/s²; for <i>P</i> = 0.98, ∆<i>a</i>_max = 167 cm/s²; for <i>P</i> = 0.99, ∆<i>a</i>_max = 273 cm/s².</p>","PeriodicalId":45174,"journal":{"name":"Seismic Instruments","volume":"58 1","pages":"S14 - S24"},"PeriodicalIF":0.9,"publicationDate":"2023-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4802349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regional Magnitude Mwa in the Russian Far East","authors":"D. A. Safonov,&nbsp;E. P. Semenova","doi":"10.3103/S074792392207009X","DOIUrl":"10.3103/S074792392207009X","url":null,"abstract":"<p>The Yuzhno-Sakhalinsk Seismological Regional Information Processing Center (RIPC) recently used the Richter magnitude <i>M</i>_<i>wa</i> to estimate the energy level of Far Eastern earthquakes. To date, this is the most common energy characteristic in the operational catalog of the RIPC. The basis is digital waveforms of regional seismic stations emulated to the characteristics of the Wood–Anderson seismograph. In the present paper, the results of determining the magnitude <i>M</i>_<i>wa</i> in Russian Far Eastern conditions are analyzed. The magnitude determination accuracy is estimated, and station corrections are obtained. The regression relation <i>M</i>_<i>wa</i> and Japanese Meteorological Agency magnitude <i>M</i>_<i>j</i> showed a high similarity between these scales. This made it possible to use <i>M</i>_<i>j</i> as the reference when studying the features of <i>M</i>_<i>wa</i>. The regional seismic network makes it possible to correctly estimate the magnitude <i>M</i>_<i>wa</i> at a regional distance (up to about 1000 km), including for deep-focus earthquakes (up to 600 km). Transfer relations between <i>M</i>_<i>wa</i> and other mass-determined regional energy characteristics of earthquakes are obtained. The <i>M</i>_<i>wa</i> scale can be used to estimate the energy level of any earthquakes in the Kuril–Okhotsk and Sakhalin regions in the magnitude range of weak and moderately strong events and is recommended for inclusion in regional earthquake catalogs for the Russian Far East.</p>","PeriodicalId":45174,"journal":{"name":"Seismic Instruments","volume":"58 1","pages":"S42 - S57"},"PeriodicalIF":0.9,"publicationDate":"2023-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4801929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Applicability of the H/V Method in the Seismic Microzoning Problem","authors":"A. V. Kalinina,&nbsp;S. M. Ammosov,&nbsp;R. E. Tatevossian,&nbsp;V. V. Bykova","doi":"10.3103/S0747923922070052","DOIUrl":"10.3103/S0747923922070052","url":null,"abstract":"<p>The paper discusses the applicability of the horizontal-to-vertical spectral ratio for ground motion (H/V method) to estimate the seismic intensity increment and trace the bedrock surface covered by soil layers. The first issue is the classic seismic microzoning problem; the second is related to structural mapping of the upper part of the geological profile. The authors assess the possibility of using a single station to estimate the intensity increment without synchronization of data at a given point at a site with records based on reference rocks. It is shown that such an approach is invalid, because the maximum variations in the H/V ratio during a day may reach 2.7 times; a degree of intensity of 0.8 will correspond to such variation. At the same time, it is shown that the resonance frequencies of soil layers are stable. If the mean velocities of seismic waves are known at some points of profile surface, the position of the underlying bedrock top can be traced with confidence.</p>","PeriodicalId":45174,"journal":{"name":"Seismic Instruments","volume":"58 1","pages":"S79 - S88"},"PeriodicalIF":0.9,"publicationDate":"2023-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4797450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The 1970 Dagestan Earthquake a Half-Century Later","authors":"A. A. Lukk,&nbsp;A. Ya. Sidorin","doi":"10.3103/S0747923922070155","DOIUrl":"10.3103/S0747923922070155","url":null,"abstract":"<p>In connection with the 50th anniversary of the destructive Dagestan earthquake on May 14, 1970, information on the parameters, manifestation features, and consequences of this seismic event was collected and summarized. The Dagestan earthquake became a very important event in the seismic history of the entire Caucasus. The reasons for this were determined by several of its features, the most important being that it was the strongest instrumentally recorded earthquake in the Caucasus at that time, and the nearest seismic station, Makhachkala, was at an epicentral distance of less than 30 km and recorded not only the main shock, but also a strong foreshock with its aftershock sequence. After the earthquake, a temporary seismic network was quickly deployed, which made it possible to trace in detail the development of the aftershock process of the main shock. Based on the literature data, the main parameters of the Dagestan earthquake and its most important consequences are discussed. The most realistic model of the source was constructed by S.S. Arefiev et al. (2004) based on data on the inversion of body waves from this earthquake. According to this model, Dagestan earthquake had a multiple source consisting of three subsources. The initial rupture (subsource), with a horizontal extent of 14 km, was located in the center of the focal zone at a depth of 9 km. The second rupture began about 2 s later, 10 km east of the first, at a depth of about 10 km and with a horizontal extent of 20 km. The third subsource was 10 km west of the first, at a depth of 12 km. The Dagestan earthquake made it possible to significantly refine the regional seismic hazard assessment. This was extremely important in regards to construction of the Chirkey hydroelectric power plant (HPP) with a high-altitude dam (232 m) in the 8-point shaking intensity zone for this seismic event. The creation of the reservoir itself during the construction of the high-pressure concrete dam of the HPP led to the impact of its filling and further seasonal fluctuations in the volume of the reservoir (about 3 billion m³) on the seismic activity in the upper part of the crust, with an area of at least 1000 km². This was the reason for the occurrence of induced technogenic earthquakes in this area. The effect of induced seismicity can be dangerous if completion of the dam and creation of the reservoir coincide in time with the natural rhythm of ordinary seismogenesis. It also turned out that powerful shaking of the upper part of the crust during the Dagestan earthquake disrupted the oil production regime in Dagestan.</p>","PeriodicalId":45174,"journal":{"name":"Seismic Instruments","volume":"58 1","pages":"S123 - S134"},"PeriodicalIF":0.9,"publicationDate":"2023-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4797865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Earthquake of April 5, 2017, MW = 6.0, in Northeast Iran: Focal Parameters, Aftershock Series, and Macroseismic Manifestations","authors":"N. V. Petrova,&nbsp;L. V. Bezmenova,&nbsp;A. D. Kurova","doi":"10.3103/S0747923922070088","DOIUrl":"10.3103/S0747923922070088","url":null,"abstract":"<p>The article considers the earthquake of April 5, 2017 with <i>M</i>_<i>W</i> _GCMT = 6.0 near the Turkmen–Iranian border, northeast of the Iranian village of Sefid Sang. During the entire seismic history of the region, this was the strongest seismic event within a 45 km radius of the epicenter. The earthquake caused widespread destruction in four villages; two people died and 100 were injured. The shaking was felt in population centers in Iran, Turkmenistan, and other countries. According to the compiled isoseist map, the northwestern orientation of isolines of equal intensity, coinciding with the strike of the nearest faults, and strong damping of the shaking intensity across tectonic structures were established. The macroseismic field equation has been established, which is close to the Blake–Shebalin equation with average world coefficients. According to both equations, the shaking intensity at the epicenter is estimated as <i>I</i>₀ = 8. The northwestern (southeastern) orientation of the aftershock cluster and their southeast migration were revealed, which made it possible to choose the nodal plane of the focal mechanism with a similar strike as the active one. The fault plane parameters, length <i>L</i> = 30 km and width <i>W</i> = 12 km, have been estimated for the area of the highest aftershock density. The law of the decrease in the number of aftershocks with time has been established, which indicates rapid decay of the aftershock process.</p>","PeriodicalId":45174,"journal":{"name":"Seismic Instruments","volume":"58 1","pages":"S1 - S13"},"PeriodicalIF":0.9,"publicationDate":"2023-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4799620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Source of the 1902 Shamakhi Earthquake on the Background of Attenuation Field Inhomogeneities and Seismicity of the Western Caspian Region","authors":"O. I. Aptikaeva","doi":"10.3103/S0747923922070027","DOIUrl":"10.3103/S0747923922070027","url":null,"abstract":"<p>The article studies the characteristics of seismic coda wave attenuation in the vicinity of the source of the 1902 Shamakhi earthquake and in adjacent zones of the Western Caspian region. The relationship between the features of seismic processes and spatial inhomogeneities of the attenuation field is considered. The attenuation field is represented by zones (blocks) with a high <i>Q</i>-factor and close to isometric in plan view, and by the linear zones of strong attenuation (weakened zones, which coincide with faults). Sources of the strongest earthquakes are confined to the zones of maximum attenuation contrast. It was revealed that the structure of the attenuation field agrees with the structure of the <i>S</i>-wave velocity field: low-velocity anomalies correspond to low-<i>Q</i> zones. Unidimensionally extended volumes of intense localized seismicity, located in weakened zones, are considered. In one of these volumes, in the focal zone of the 1902 Shamakhi earthquake, manifestations of active deep degassing processes were observed: mud volcano eruptions and earthquake swarms with upward-moving sources during a series have been recorded. It is noted that the most remarkable seismic events, and, above all, the major 1902 Shamakhi earthquake, correlate with the minima of the Earth’s rotation speed.</p>","PeriodicalId":45174,"journal":{"name":"Seismic Instruments","volume":"58 1","pages":"S67 - S78"},"PeriodicalIF":0.9,"publicationDate":"2023-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4802363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}