The influence of gas saturation and pore pressure on the characteristics of the Frenkel-Biot <Emphasis Type="Italic">P</Emphasis> waves in partially saturated porous media     

D. N. Mikhailov 《Izvestiya Physics of the Solid Earth》2010,46(10):897-909

For the case of a partially saturated porous medium, analysis of the conditions is carried out under which the properties of the Frenkel-Biot P waves are similar. The condition of dynamic compatibility (with fulfillment of which a wave of the first kind is propagated without attenuation) is generalized to the case of partially saturated porous media. It is found that the wave connected with the matrix deformation possesses a high attenuation coefficient in a porous medium saturated with a weakly-compressible liquid, but it is a weakly decaying wave in a gas-saturated porous medium. Asymptotic formulas for phase wave velocities are obtained within a low-frequency and high-frequency limit for the general case of a partially saturated porous medium. It is shown that in the domain of low gas saturation, the attenuation coefficient of a wave of the first kind (i.e., a wave connected with the compressibility of phases) depends on the state of the gas in porous space. The following three cases are considered: (1) the microbubbles occluded in the saturating liquid; (2) the microbubbles adsorbed on the walls of pores; and (3) the macrobubbles that completely occupy one or several pores. This characteristic can be used as the diagnostic parameter.  相似文献   

Joint inversion of the differential satellite interferometry and GPS data: A case study of Altai (Chuia) Earthquake of September 27, 2003     

V. O. Mikhailov  A. N. Nazaryan  V. B. Smirnov  M. Diament  N. Shapiro  E. A. Kiseleva  S. A. Tikhotskii  S. A. Polyakov  E. I. Smol’yaninova  E. P. Timoshkina 《Izvestiya Physics of the Solid Earth》2010,46(2):91-103

Based on the data of differential satellite interferometry, the field of displacements of the Earth’s surface in the line-of-sight direction is determined for the region of the Altai Earthquake that struck on September 27, 2003. The displacements are estimated for unforested areas of Chuia and the Kurai depressions, and for a part of their mountainous surroundings. In that part of the region where unwrapping of the data was possible, the amplitude of displacements amounts up to 150 cm for Chuia and 100 cm for the Kurai depressions. In order to locate the surface of the seismic rupture and to find the field of displacements on this surface, the method for the combined inversion of the displacements data, provided by satellite interferometry (the present work) and geodesy [Gol’din et al., 2005], is suggested and applied. The admissible range of the parameters of the rupture was specified from the seismology and seismotectonics data. The combined use of geodetic and satellite interferometry data makes the solution of the inverse problem more stable and yields a seismic momentum estimate, which is consistent with the seismological determinations. We discuss the possible contributions of various postseismic processes; in particular, based on analyzing the energy of the aftershocks, we assess the contribution of the postseismic creep to the displacements, determined from the interferometry and geodesy data, for different coseismic and postseismic time intervals.  相似文献   

VLF electromagnetic background in the seismoactive area of Northern Vietnam     

K. Kh. Truong  T. S. Vo  Yu. M. Mikhailov  A. L. Kharitonov  O. V. Kapustina 《Geomagnetism and Aeronomy》2010,50(5):690-694

The preliminary results of observations of VLF electromagnetic signals (atmospherics) in the mountains of North Vietnam (Dien Bien Phu, 21°23′50″ N, 103°0′28″ E) are presented. Primarily, signals of typical atmospherics with a maximum in the frequency range of 4–9 kHz were observed; sometimes they were accompanied by so-called “tails” at frequencies less than 1 kHz, and also tweeks of usually short duration (about 10 ms) were observed. Several parameters of the ionosphere, as well as the distance to sources of atmospherics (in accordance to the data of the World Wide Lightning Location Network (TOGA)), were estimated by spectral-temporal characteristics of tweeks.  相似文献   

Experimental evidence of the correlation between possible precursors of earthquakes in near-surface quasistatic electric fields and in the ionosphere     

L. P. Korsunova  Yu. M. Mikhailov  V. V. Khegai  L. N. Leshchenko  S. E. Smirnov  V. V. Bogdanov 《Geomagnetism and Aeronomy》2010,50(7):920-926

We consider data obtained when the parameters of the ionospheric E_s and F2 layers and the vertical gradient of the electric potential in the surface atmosphere were simultaneously measured during the preparatory period of crustal earthquakes with M = 5.0–6.2 in the Kamchatka region. The appearance of anomalously high E_s, accompanied by an increase in frequency parameters of the sporadic layer and the regular F2 layer, was detected on days when possible earthquake precursors, as determined earlier, occurred in atmospheric electric fields. The presumed earthquake precursors in the ionosphere are divided into two groups with different earthquake lead times ranging from several hours to two weeks. Empirical dependences are presented that connect the lead time of an earthquake (from the moment of the appropriate anomaly’s occurrence in the ionosphere or in the atmospheric electric field to the moment of the shock) and the epicentral distance to the observation point with the earthquake magnitude. These dependences are different for the two groups of presumed earthquake precursors, but they are close inside each group of possible precursors selected on the basis of quasistatic electric field measurements and revealed in ionospheric parameter variations.  相似文献   

Effects of thunderstorm activity in power spectra of the electric field in the near-surface atmosphere at Kamchatka     

G. A. Mikhailova  Yu. M. Mikhailov  O. V. Kapustina  S. E. Smirnov 《Geomagnetism and Aeronomy》2010,50(6):814-823

We have performed a spectral analysis of variations in the E _z component of a quasistatic electric field in the atmospheric surface layer in a wide band of internal gravity waves (from 5 min to 3 h) for quiet and seismically active conditions as well as high thunderstorm activity. Observational data of the field for September, 1999 and August–September, 2002, were used. It has been shown that, if there are no thunderstorms or earthquakes, the background spectrum includes oscillations with maxima at periods of T ∼ 1.8 and 1 h, 40, 30, 15, and 10–13 min. Their intensity in the range of periods of 0.5–3.0 h is two or more orders of magnitude higher than the intensity of maxima in the range of 5–30 min. Before earthquakes, with anomalies in diurnal variations of field intensity, there is a tendency of increased background spectrum at maxima noted there. In both ranges of oscillation periods, the spectral intensity increases by one to one and a half orders of magnitude. Under high thunderstorm activity, the variability is higher as compared to the spectra of earthquake precursors by both locations of maxima and their intensity. The intensity of maxima exceeds the maxima on the eve of earthquakes one to one and a half orders of magnitude in the range of periods 0.5–3.0 h and two and more orders of magnitude in the range of periods 5–30 min.  相似文献   

Torus Dynamo Model for Study of Magnetic Fields in the Outer Rings of Galaxies     

E. A. Mikhailov 《Astrophysics》2018,61(2):147-159

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Spatial and time variations in critical frequencies of the ionospheric <Emphasis Type="Italic">F</Emphasis> region above the zone of equatorial earthquake preparation     

A. Kh. Depueva  A. V. Mikhailov  M. Devi  A. K. Barbara 《Geomagnetism and Aeronomy》2007,47(1):129-133

Spatial and time variations in the critical frequencies foF2 before the strong earthquake of August 15, 1963, with the magnitude M = 7.75 are analyzed. The epicenter of the earthquake was located in the vicinity of the magnetic equator in the American longitudinal sector. The data of the topside ionosonde on board Alouette-1 and of the series of ground-based ionosondes has been used for this purpose. The ground-based ionosondes made it possible to detect an insignificant anomalous decrease in foF2 within the zone of earthquake preparation a few days prior to the earthquake. This result confirms the conclusion drawn earlier on the basis of the satellite data. The modification of the ionosphere at the F-region level is more evident in the satellite than in the ground-based data. It is also noted that the character of the time variations in foF2 a day before the earthquake is similar to the so called “quiet time” Q-disturbances in the ionosphere, when the electron concentration at the F region maximum differs from the median values by more than 20% under undisturbed geophysical conditions.  相似文献   

Parametric Structural Approach to Constructing Digital Models of the Relief and Gravitational Field of the Earth Using Analytical S-Approximations     

Stepanova  I. E.  Shchepetilov  A. V.  Pogorelov  V. V.  Mikhailov  P. S. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(8):859-868

Izvestiya, Atmospheric and Oceanic Physics - This paper discusses the peculiarities of applying the parametric structural approach to constructing analytical approximations of the relief of the...  相似文献   

Determination of the Magnitude of the Spins of Supermassive Black Holes and the Magnetic Fields in Active Galactic Nuclei     

A. G. Mikhailov  Y. N. Gnedin  A. V. Belonovsky 《Astrophysics》2015,58(2):157-167

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Orbital monitoring of the ionosphere and abnormal phenomena by the small Vulkan-Compass-2 satellite     

V. D. Kuznetsov  L. Bodnar  G. K. Garipov  V. A. Danilkin  V. G. Degtyar  V. S. Dokukin  T. A. Ivanova  O. V. Kapustina  V. E. Korepanov  Yu. M. Mikhailov  N. N. Pavlov  M. I. Panasuyk  I. S. Prutenskii  I. A. Rubinshtein  Yu. Ya. Ruzhin  V. M. Sinelnikov  V. I. Tulupov  Ch. Ferents  A. V. Shirokov  I. V. Yashin 《Geomagnetism and Aeronomy》2011,51(3):329-341

Natural disasters, the processes of their origin and large-scale technogenic catastrophes are accompanied by anomalous physical phenomena in near-Earth space (NES). In order to reveal such phenomena, record and investigate them, complex NES monitoring is required with the use of specially designed research equipment onboard a low-orbiting spacecraft. This work presents the results of flight tests of the small Vulkan-Compass-2 satellite with research equipment specially designed for orbital monitoring of the ionosphere and search for abnormal phenomena caused by large-scale catastrophes of different nature.  相似文献