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1.
Andriy Gnyp 《Acta Geophysica》2009,57(2):330-345
Based on the results of application of correlation analysis to records of the 2005 Mukacheve group of recurrent events and
their subsequent relocation relative to the reference event of 7 July 2005, a conclusion has been drawn that all the events
had most likely occurred on the same rup-ture plane. Station terms have been estimated for seismic stations of the Transcarpathians,
accounting for variation of seismic velocities beneath their locations as compared to the travel time tables used in the study.
In methodical aspect, potentials and usefulness of correlation analysis of seismic records for a more detailed study of seismic
processes, tectonics and geodynamics of the Carpathian region have been demonstrated. 相似文献
2.
Vo?V.?Anh Philip?Broadbridge Andriy?Olenko Yu?Guang?WangEmail authorView author&#;s OrcID profile 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(9):2585-2603
This paper gives the exact solution in terms of the Karhunen–Loève expansion to a fractional stochastic partial differential equation on the unit sphere \({\mathbb {S}}^{2} \subset {\mathbb {R}}^{3}\) with fractional Brownian motion as driving noise and with random initial condition given by a fractional stochastic Cauchy problem. A numerical approximation to the solution is given by truncating the Karhunen–Loève expansion. We show the convergence rates of the truncation errors in degree and the mean square approximation errors in time. Numerical examples using an isotropic Gaussian random field as initial condition and simulations of evolution of cosmic microwave background are given to illustrate the theoretical results. 相似文献
3.
Filipa Tavares Wahren Maria Tarasiuk Andriy Mykhnovych Myron Kit Karl-Heinz Feger Kai Schwärzel 《Environmental Earth Sciences》2012,65(5):1501-1510
Integrated watershed models require spatially differentiated soil information. However, in many regions of the world the limited
availability of soil data hinders an appropriate simulation of hydro-ecological processes. Such circumstances lead to unsupported
statements, poor statistics, misrepresentations, and, ultimately, to bad resource management. The Western Bug catchment in
west Ukraine is an example of such a region. In the former Soviet Union, soil classification primarily focused on soils of
agricultural importance, whereas, forested, urban, industrial, and shallow soil territories were left underrepresented in
the classification and soil maps. Spatially differentiated soil texture data are required to predict soil hydraulic properties
using pedotransfer functions (PTFs), along with soil maps. Furthermore, the Ukrainian soil texture scheme does not match the
particle size classes commonly used with PTFs. To overcome these shortcomings, a fuzzy logic methodology was applied, based
on terrain and vegetation/land use analysis and soil sampling, to close the information gaps. For the application of PTFs,
a procedure was tested to estimate missing values of soil texture distribution. Applied methods were evaluated using recent
soil surveys, measured soil texture, and water retention properties, while having in consideration the limitations brought
by scarce soil data for integrated watershed modelling purposes. 相似文献
4.
The most widespread instrument used today for the measurement of quasi-stationary and slowly fluctuating vector magnetic fields is a flux-gate magnetometer (FGM). The most important parameter characterizing the magnetometer quality is its magnetic noise—its threshold sensitivity or its own noise level (NL). Based on the results of experimental research, we may state that the FGM NL mainly depends on the quality of the magnetic material used for FGM sensor core. The “solid liquid” model explaining the nature of magnetic noise is proposed and substantiated. It is demonstrated that special attention has to be paid to the annealing of the core. A new effect—termed gamma-magnetic normalization—is discovered and discussed. It is shown that the magnetometer NL depends not only on the core length and volume but also on the excitation mode of the core. Besides, the ways to improve other factors, such as power consumption and thermal drift which must be taken into account in order to create a FGM with the highest possible performance, are discussed. Some examples are given of the parameters of present advanced FGMs for geophysical uses. 相似文献
5.
Andriy Gnyp 《Acta Geophysica》2010,58(4):587-603
Three groups of recurrent events have been identified within the 2005–2006 Mukacheve series of about forty M
SH
0.3–1.8 near-surface earthquakes. After a cross-correlation analysis of their waveforms and subsequent relocation with application
of the adjusted arrivals and station terms it turned out that they most likely belong to at least two distinct crustal layers
separated by an interface at about 4 km; the seismic activation started deeper and progressed upwards. As concerns polarities
of first arrivals, the same source mechanism was inferred within individual groups, indicating a normal faulting along the
Az ≈ 120° with a slight component of right lateral slip; this finding is consistent with data available on some other local
sources, as well as with an ambient field of extensional stresses in the local crust and a significant horizontal gradient
of vertical movements across the epicenter area of the Mukacheve series. 相似文献
6.
Shigeaki Ono Artem R. Oganov John P. Brodholt Lidunka Vo
adlo Ian G. Wood Andriy Lyakhov Colin W. Glass Alexander S. Ct G. David Price 《Earth and Planetary Science Letters》2008,272(1-2):481-487
Iron sulfide (FeS) was investigated using first-principles calculations up to a pressure of 400 GPa. A number of new phase transitions were found. An antiferromagnetic MnP-type structure, FeS II, was confirmed to be stable at low pressures, whereas at high pressures (40–135 GPa) we find a new stable phase, with a non-magnetic MnP-type structure, FeS VI. The observed first-order change in the cell shape between the two phases can be explained by the difference in magnetic configurations. The calculated cell parameters, atomic coordinates, and bulk modulus of non-magnetic MnP-type phase are consistent with those determined from experiment. The upper pressure limit of the stability of the non-magnetic MnP-type phase was calculated to be 135 GPa. A hitherto unsuspected phase transition from the non-magnetic MnP-type to a phase with Pmmn symmetry, FeS VII, was identified using the evolutionary crystal structure prediction (USPEX) method. The structure of the Pmmn phase has no known analogues, but can be described as a distortion of the NaCl-type structure. The Pmmn phase with the distorted NaCl-type structure is stable from 135 GPa at least up to 400 GPa. According to previous experiments and the present study, the transition sequence of FeS at low temperatures is as follows: troilite ➔ antiferromagnetic MnP-type phase ➔ monoclinic phase ➔ non-magnetic MnP-type phase ➔ Pmmn phase. The calculated volume reduction from the monoclinic to the non-magnetic MnP-type phase is 1.0% at 40 GPa, which is in good agreement with experimental observations. The calculated volume reduction from the non-magnetic MnP-type to the Pmmn phase is 3.7% at 135 GPa. 相似文献
7.
Andriy Gnyp 《Acta Geophysica》2014,62(6):1246-1261
Relative locations of recurrent earthquakes can be recovered from values of cross-correlation coefficients between their waveforms at a single station, provided that an idea of Menke (1999) that the values depend inversely exponentially from separation between the sources is true. An algorithm developed in Gnyp (2013) based on this idea was applied here for recovering relative locations of the two groups of the 2005–2006 recurrent earthquakes in Mukacheve, Ukraine, from the sets of cross-correlation coefficients between their records at the four local network stations to find out whether the locations were in principle reproducible independently at each of the stations, at epicentral distances from about 6 to 64 km. The resulting sets of locations occurred in good agreement with each other, which may be considered as an experimental evidence for validity of the Menke’s dependence over the corresponding range of distances. The reproducibility of relative locations has been analyzed in terms of existence and uniqueness of the inverse problem’s solution, and in connection with data completeness and the influence of noise on it. 相似文献
8.
9.
Andriy Gnyp 《Acta Geophysica》2013,61(5):1074-1087
An algorithm was designed for inverting the set of cross-correlation coefficients between the records of recurrent earthquakes by a single station for their relative locations based on an assumption of Menke (1999) that the cross-correlation is only a function of separation between the sources and decays exponentially with it. Tested on synthetic data sets, the algorithm easily recovered the true relative locations, the initial ones seeded randomly. Inversion of the cross-correlation coefficients between the records of the two groups of the Mukacheve 2005–2006 recurrent earthquakes by the station Mukacheve steadily produced an almost flat shape of hypocenter cloud for each of the groups, final relative locations of hypocenters being almost the same for different initial seedlings. The combined set of cross-correlation coefficients for both groups was also inverted, and the shape of the combined hypocenter cloud was almost flat again. These results compare well with ones obtained earlier (Gnyp 2010) by relocating the Mukacheve earthquakes with the use of differential arrivals and source specific station terms. 相似文献
10.
Svetlana Kováčiková Igor Logvinov Andriy Nazarevych Lesya Nazarevych Josef Pek Victor Tarasov Pavel Kalenda 《Studia Geophysica et Geodaetica》2016,60(2):280-296
We present results of a study of the seismicity and the geoelectric structure of the Eastern Carpathians. After the evaluation of the seismicity, new methods of processing and analyzing seismic data are developed, which allow constructing an averaged horizontal-layered velocity model of the crust in the Carpathian region of Ukraine, tracing the seismic active faults and localizing the seismic events both in horizontal and in vertical direction with a better precision. For the study of the conductivity structure beneath the Eastern Carpathians, the collected magnetovariation and magnetotelluric data are used. The depth of electrical conductivity anomalies are estimated and the resulting quasi-3D model of the conductivity structure beneath the Carpathians is compared with the seismicity in the depth range of 10 ± 2.5 km. The comparison suggests possible geological mechanisms: the seismic events occur mainly in resistive solid rock domains which surround aseismic high-conductivity zones, consisting of at least partially melted material. Aqueous fluids, or a joint effect of several mechanisms, may also play an active role in this distribution. 相似文献