Geophysical Research最新文献

{"title":"RELATIONSHIP BETWEEN PRECEDING SEISMICITY AND THE PROBABILITY OF STRONG AFTERSHOCK OCCURRENCE","authors":"S. Baranov, P. Shebalin","doi":"10.21455/gr2019.3-1","DOIUrl":"https://doi.org/10.21455/gr2019.3-1","url":null,"abstract":"The paper considers the relationship of seismicity, preceding the main shock, with the emergence probability of strong aftershocks in the future series. (Strong aftershock in the sense of Bath's law means that its magnitude not lower than the average difference of magnitudes of the strongest aftershocks and their mainshocks.) A hypothesis of the research – strong aftershocks are more likely to occur due to mainshocks occurred in places of high background seismicity. Testing the hypothesis at the global level was carried out using ANSS ComCat earthquake catalog US Geological Survey, at the regional level – using earthquake catalogs provided by Geophysical Service of the Russian Academy of Sciences for seismic regions of Russia (Kamchatka and the Kuril Islands, Baikal and Transbaikalia, the North Caucasus). We tested several functions that characterize previous background seismic activity relative to the mainshock. The values of the functions were considered as a possible precursor or anti-precursor of a strong aftershock. The effectiveness of the precursor (anti-precursor) was evaluated by a specially developed criterion, representing the ratio of the sum of all successful forecasts to the number of all unsuccessful forecasts. The value at which the maximum efficiency is achieved was taken as a threshold. The value of the previous activity greater or less than the threshold was considered as a precursor or anti-precursor of a strong aftershock, respectively. As a result, the hypothesis of the study was confirmed at the global and regional levels, regardless of the method of measuring previous seismic activity. The most informative characteristic of activity is the ratio of the accumulated seismic moment of background earthquakes preceding the main shock to the time of the main shock, normalized to the area of the circle bounding the background seismicity region. The probability of expected repeated shocks was estimated using the Reasenberg–Jones model depending on time and magnitude. We estimated the model parameters for the Earth and seismically active regions of Russia both with and without preceding seismicity. Comparison of theoretical and model values of the probability of occurrence of at least one strong aftershock at different time intervals showed that the model corresponds well with the initial data. Using the probabil ity gain, we shown that Reasenberg–Jones model, which takes into account preceding background seismicity, is more preferable than the model without it.","PeriodicalId":36772,"journal":{"name":"Geophysical Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68270686","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":"THREE-DIMENSIONAL MODEL OF GENERATION OF ATMOSPHERIC INTERNAL GRAVITY WAVES INDUCED BY INHOMOGENEITIES IN GRAVITATIONAL FIELD","authors":"L. Ingel, A. A. Makosko","doi":"10.21455/gr2019.1-1","DOIUrl":"https://doi.org/10.21455/gr2019.1-1","url":null,"abstract":"In modern models of geophysical fluid dynamics, the gravitational field is usually taken uniform and defined by the single parameter. It is known, however, that the average gravitational force at the earth’s surface is superimposed upon by a broad spectrum of gravitational force anomalies (GFAs). This is due mainly to inhomogeneities of the distribution of mass in the Earth’s crust. Variations in the gravitational force are certainly very small in magnitude compared to the average value. It is important, however, that such inhomogeneities generate a gravitational-force component tangential to earth's ellipsoid. In plane mesoscale models using Cartesian coordinates (an f-plane or a β-plane), this means that additional volume inhomogeneous forces with a horizontal component have to be taken into account. The dynamics of the atmosphere is quite sensitive to such components. Recently we showed that in the highly anomalous regions GFAs, in principle, can lead to appreciable dynamic effects, in particular, the generation of regular currents and internal gravity waves (IGW). But this analysis has so far been limited to two-dimensional problems (that is, the effects of two-dimensional GFAs were considered). In this paper, the next step is taken: in the linear approximation, IGW generation in the atmosphere is analytically studied under the action of three-dimensional GFAs on the atmospheric flow above a flat horizontal underlying surface. The terms in the expressions obtained for velocity components and pressure perturbations can be divided into two categories. One of them directly describes flow around equipotential surfaces. These terms do not contain waves propagating with vertical component and slowly decay with altitude on the same scales as the gravity anomaly. Other terms describe internal gravity waves, whose phase velocity is directed downward and the group velocity, upward. The amplitude of these waves in the velocity field exponentially increases with altitude. Taking into account the three-dimensional geometry of GFAs in the three-dimensional formulation can lead to a noticeable change in results in comparison with the two-dimensional model considered earlier. In addition to the appearance of horizontal motions perpendicular to the background flow, the wavelength and the vertical flux of wave energy can markedly vary: GFAs elongated along the stream can lead to smaller perturbations in amplitude than the “ridge” oriented perpendicular to the background flow. The analytical expression is derived; it shows that the mentioned energy flow is proportional to the background buoyancy frequency, to the squares of the GFAs amplitudes, and to the background flow velocity. According to numerical estimates, this flow can be noticeable, although it is usually much inferior to IGW sources associated with the relief.","PeriodicalId":36772,"journal":{"name":"Geophysical Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68270396","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":"IMPROVEMENT OF METHODICAL RECEPTIONS FOR LOG DATA INTERPRETATION AT EXPLORATION AND DEVELOPMENT OF INFILTRATION URANIUM MINE FIELDS","authors":"D. A. Legavko","doi":"10.21455/gr2019.2-3","DOIUrl":"https://doi.org/10.21455/gr2019.2-3","url":null,"abstract":"The description of the software realization for automated interpretation method of primary logging complex data in open hole of technological wells, constructed during the development of infiltration uranium mine fields by in situ leaching method is presented. The description of the software module that implements the previously developed methodical approach for interpretation of resistance logging data in the sandy-clay section is provided. Short characteristics of the program for gamma-ray logging data interpretation and calculation of linear stocks of uranium with using the method of morphological join of balance ore intervals are given.","PeriodicalId":36772,"journal":{"name":"Geophysical Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68270580","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":"ESTIMATION OF SEISMIC AZIMUTHAL ANISOTROPY PARAMETERS OF THE UPPER MANTLE OF THE CENTRAL PART OF THE EAST-EUROPEAN CRATON ACCORDING TO THE DATA OF THE “OBNINSK” AND “MIKHNEVO” SEISMIC STATIONS","authors":"V. Adushkin, A. Goev, I. Sanina","doi":"10.21455/gr2019.3-2","DOIUrl":"https://doi.org/10.21455/gr2019.3-2","url":null,"abstract":"The results of determining the parameters of seismic anisotropy of the upper mantle of the central part of the East-European craton are given. According to the tectonic concepts actively developing in recent decades, the East-European craton consists of megablocks (microplates) of different age: there are three main megablocks – Fennoscandia, Volga-Uralia and Sarmatia. The area of their triple junction is the subject of this article. The SKS/SKKS anisotropy method was applied. Its essence is to use SKS phases in order to obtain delay times for the arrival of two quasi-shear waves that are formed during the trace of a shear wave through an anisotropic medium and gets through it with different velocities. The result is to simulate the azimuth of the maximum velocity axis along which “fast” quasi-shear wave trace and to get the delay time between “fast” and “slow” waves. The technique does not allow to obtain accurate estimates of the depth of the anisotropic layer, however, taking into account the long periods of the SKS wave and the pronounced anisotropic properties of olivine, as the main material composing the upper mantle, it is assumed that these effects are related to the mantle processes. Authors used the data from “Obninsk” (OBN) and “Mikhnevo” (MHV) stations that are located in the zone of the triple junction of blocks. For Obninsk station – 1266 events were used, for Mikhnevo station – 472. For each station, we obtained estimates of the azimuth of the maximum speed axis and the delay time of arrival of quasi-shear waves. As a result of the study, the mantle anisotropy of the region is assessed as weak, which is an expected result for tectonically stable platform regions (delay time 0.4 s for the OBN station and 0.2 s for the MHV station). The direction of the maximum speed axis is strictly sub-latitude (90 for the OBN and 100 for MHV station), which is in accordance with the known the East-European lithospheric plate motion. For the OBN station, two groups of events were identified, with significantly different results, structured by azimuth. For events mainly with western azimuths of arrival of seismic waves, the solution is 90 and 0.4 s, while processing events from the eastern direction of arrival, along with a coordinated solution, a second pronounced local extremum is detected, corresponding to angles and delay time about 0.5–1.0 s. According to the results of MHV data processing, a second local extremum was also found, corresponding to similar angles of about 160, however, with a shorter delay time (about 0.1–0.2 s). It can be assumed that the presence of two extrema is associated with the anisotropic parameters of two different megablocks, near the junction boundary of which are located the OBN and MHV stations.","PeriodicalId":36772,"journal":{"name":"Geophysical Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68270249","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":"MAPPING OF VOLCANIC STRUCTURES OF WESTERN-TRANSBAIKALIA PROMISING FOR THE SEARCH OF MINERAL DEPOSITS BASED ON THE ANALYSIS OF AEROMAGNETIC DATA","authors":"P. Goryachev","doi":"10.21455/gr2019.2-6","DOIUrl":"https://doi.org/10.21455/gr2019.2-6","url":null,"abstract":"The method for analyzing the distribution of points with extreme values of the effective magnetization obtained as a result of solving the inverse problem using materials of high-precision aeromagnetic survey is presented. To study the structure of volcanic structures and make recommendations for their mapping, the processing of magnetic data was performed using the Baltika interpretation system. A feature of the algorithm for formalized calculation of the physical properties of the medium implemented in this system is the use of the gradient model. It is accepted that the physical properties of the model in the horizontal direction change according to a polynomial law, and in the vertical direction – in a piecewise linear manner. On the basis of the obtained distribution, points with extreme values of the effective magnetization and the corresponding equivalent regions were distinguished. The results of solving the inverse problem of magnetic potential, obtained for the Naran region, are presented. These data allow us to predict the features of the geological section formed by rocks with various magnetic properties and to map volcanic-dome structures.","PeriodicalId":36772,"journal":{"name":"Geophysical Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68270594","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":"ON THE NONSTATIONARY PROCESSES IN GEOPHYSICAL MEDIA","authors":"A. Guglielmi, A. Potapov","doi":"10.21455/gr2018.4-1","DOIUrl":"https://doi.org/10.21455/gr2018.4-1","url":null,"abstract":"In this methodological article we consider the effects that arise from the nonstationarity of the geospheres, namely, the magnetosphere, the atmosphere, and the lithosphere. The intensification of convection in the magnetosphere during the geomagnetic storm leads to the self-excitation of the electromagnetic ULF oscillations of the increasing frequency in the dusk sector. The paper gives a vivid example of observing oscillations of the increasing frequency at the mid-latitude Mondy station. It illustrates the exceptional complexity of nonstationary processes actually occurring in the magnetosphere. In the upper atmosphere (in the ionosphere), after the sunset, the source of ionization is turned off and the electron concentration begins to decrease. The nonstationarity of the medium consists in a monotonous decrease in the temperature of the atmosphere after the sunset, and it is manifested in the fact that the evolution of the electron density deviates noticeably from the prediction on the basis of a simple theory of recombination. This example is interesting in that it gives the key to understanding the known deviation of the aftershocks stream in the lithosphere from the simple Omori hyperbolic law. The marked analogy gives us an idea, firstly, to present the law in the form of a differential equation for the evolution of aftershocks and, secondly, gives us a non-trivial generalization of the Omori law, which takes into account the nonstationarity of the earthquake focus “cooling off” after the main shock. Methodologically, the above examples are supplemented by the hose MHD instability in the expanding solar corona, and the Jeans gravitational instability in the expanding Universe. The general conclusion is that it is necessary to carefully analyze the possible manifestations of the nonstationarity of the environment, even if the nonstationarity is smooth and, at first glance, is irrelevant.","PeriodicalId":36772,"journal":{"name":"Geophysical Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48281370","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":"MORPHOLOGY OF REGIONAL MAGNETIC ANOMALIES IN THE BAIKAL RIFT ZONE AND SURROUNDING TERRITORY","authors":"","doi":"10.21455/gr2018.4-3","DOIUrl":"https://doi.org/10.21455/gr2018.4-3","url":null,"abstract":"","PeriodicalId":36772,"journal":{"name":"Geophysical Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42183619","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":"MODERN GEODYNAMICS OF THE SOUTHERN OF THE YENISEI RIDGE DERIVED FROM THE RESULTS OF SATELLITE OBSERVATIONS","authors":"","doi":"10.21455/gr2018.4-5","DOIUrl":"https://doi.org/10.21455/gr2018.4-5","url":null,"abstract":"","PeriodicalId":36772,"journal":{"name":"Geophysical Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46989369","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":"UPDATE OF PARAMETERS OF SOME SEISMIC EVENTS IN THE VORKUTA AREA WITHIN 1971–2016","authors":"","doi":"10.21455/gr2018.4-4","DOIUrl":"https://doi.org/10.21455/gr2018.4-4","url":null,"abstract":"","PeriodicalId":36772,"journal":{"name":"Geophysical Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46097187","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":"SOURCEWISE APPROXIMATION OF GEOPOTENTIAL FIELDS. FROM THEORY TO PRACTICE","authors":"","doi":"10.21455/gr2018.4-2","DOIUrl":"https://doi.org/10.21455/gr2018.4-2","url":null,"abstract":"","PeriodicalId":36772,"journal":{"name":"Geophysical Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68270340","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}