共查询到20条相似文献，搜索用时 31 毫秒
1.
G. I. Dolgikh S. G. Dolgikh V. A. Chupin Yu-Hung Hsiao 《Doklady Earth Sciences》2016,471(2):1257-1260
This paper is focused on analysis of comprehensive experimental research data on the infragravitational range of periods (from 20 s to 10–12 min) obtained by synchronous measurements of fluctuations in deformations of the Earth’s crust and atmospheric and hydrospheric pressure variations. It is established that the identified variations in the period range of 1–4 min are rarely observed in records of a laser nanobarograph and laser instrument for measuring hydrospheric pressure variations (laser hydrophone), while they are frequently observed in records of laser strainmeters at a variation period of 3–4 min. Oscillation excitation in the period ranges of 7–13 min, especially in the period ranges of 8–12 min, is largely related to atmospheric processes in the corresponding periods. 相似文献
2.
Strong vibrations of the Earth’s crust in the frequency range of 7–9 Hz, referred to as the “voice of the sea,” have been recorded in the course of processing synchronous experimental data obtained during recording of variations in the deformation of the Earth’s crust using a shore laser strainmeter, atmosphere pressure variations using a laser nanobarograph, and hydrosphere pressure variations using a laser meter for hydrospheric pressure and wind velocity variations. The nature of these vibrations and their transformation to adjacent geospheres have been discussed. 相似文献
3.
G. I. Dolgikh S. S. Budrin V. V. Ovcharenko A. A. Plotnikov 《Doklady Earth Sciences》2016,470(1):950-952
We analyze experimental data collected in Vityaz Bay of the Sea of Japan during study of the peculiarities of spreading of hydroacoustic waves over a shelf with decreasing depth. We found that the waves propagate over a shelf with depths greater than half of the hydroacoustic wave according to the law of cylindrical divergence with least losses of the wave energy. If the depths are shallower than half of the hydroacoustic wave, they spread along the water-bottom boundary as Rayleigh waves of decaying and undamped types with significant absorption of the wave energy by the bottom. 相似文献
4.
The results of synchronous measurements of temperature variations in a near-bottom thermocline, as well as microdeformations
of the Earth’s crust and atmospheric pressure pulsing, recorded on-shore with the help of a laser strainmeter and laser nanobarograph,
are presented. A string containing 20 thermosensors spaced at 0.5 m was used; it was placed by an anchored buoy in a place
with 21-m depth and 500 m away from the shore. A good correlation between microdeformations and atmospheric pressure variations
was observed for periods longer than 6 h. Quantitative estimates and spectral analysis via the Gilbert-Huang method for investigation
of nonstationary and nonlinear processes lead to the conclusion that, on temporal scales from tidal to several minutes, the
predominant way of formation of microdeformations in the Earth’s crust can be breaking of internal waves in a thermocline
that leads to shallow water (i.e., in the zone of “internal breakers”). 相似文献
5.
The results of regular instrumental observations over geomagnetic field variations in the zones of influence of tectonic faults
during movement of seismic waves of varied intensity are presented. It has been shown that seismic waves with an amplitude
more than 5–10 μm/s, traveling across the fault zone, always produced geomagnetic field variations. At weaker seismic disturbances,
geomagnetic field variations are of the “glimmer” character, and the relative frequency of appearance of the effect drops
as the seismic wave amplitude decreases. The quantitative dependence between the maximal value of the full vector of variations
in geomagnetic field induction in a fault zone and the amplitude of the seismic disturbance has been found for the first time. 相似文献
6.
The analysis of available theoretical evaluations and experimental data reveals discrepancies and makes it possible to formulate the goals for the comprehensive study of the behavior of enstatite MgSiO3 in shock isentropic waves of various scale and intensity. The paper presents the layout and results of an explosion experiment on the compression of an enstatite sphere with spherical shock waves and the subsequent recovery of the experimental material and its examination in discrete zones (along the sphere radius) that were produced by shock waves in the material. The latter were examined with the application of scanning electron microscopy, Raman spectroscopy, and X-ray diffraction analysis. The comparison of the systematic variations in the texture, chemistry, and phase composition of enstatite along the sphere radius with calculated pressure P(R, t) and temperature T(R, t) values led us to the following conclusions: enstatite starts melting on an isentrope upon pressure relief after shock wave compression at ?? xx ?? 80 GPa and melts on the front of the spherically converging shock wave at ?? xx ?? 160 GPa and T ?? 6300 K. Our laboratory experiments with shock waves were the world??s first in which enstatite was loaded with spherical converging shock isentropic waves and which provided evidence that shock wave-loaded MgSiO3 shows certain morphological and mineralogical features never before detected in this mineral loaded with plane shock wave of smaller amplitude and duration. Goals are formulated for the further studying of shock wave-loaded materials, and the necessity is discussed for conducting an explosion experiment with a five to seven times greater spherical system in order to increase the duration of the shock wave loading impulse. 相似文献
7.
The dynamics of magmatic melts in the near-surface part of several kilometers depth is determined by gas release processes.
Formation of free gas share is an energy source, while decreasing of the density of the melt creates conditions for magma
motion to the Earth’s surface. As the water content in the total volume of gas is about 80% for magmatic basaltic melts, gas
release of water in the near-surface part of the magmatic column realizes the main share of energy, which leads to volcanic
bursts and continuous gas-ash flows throughout the eruption process. Gas release processes create pressure variations in magmatic
melts, and these variations are transferred into the solid medium as elastic oscillations forming seismic waves. The principal
frequency of seismic signals for active volcanoes is several hertz, and the presence of spectral peaks has been explained
by the presence of resonant sources. 相似文献
8.
Measurements of intensities at two fixed wavelengths in the OH (7-2) band were carried out at Mt Abu (24.6° N, 76.7° E) from
1973–76 to estimate neutral temperature in the region of 80–90 km altitude. It was observed that on some nights the temperature
in this region shows periodic oscillations throughout the night. It was found from statistical analysis that the periods of
these fluctuations are comparable to the theoretically predicted periods of internal gravity waves.
If the periodic temperature variations observed in this region are attributed to the influence of gravity waves, according
to the Hines theory only the magnitude of the horizontal component of wave-induced wind velocity can be computed. Using the
measured relative temperature fluctuations it is found that the magnitude is 15–30 m/sec. 相似文献
9.
Yu. I. Troitskaya D. A. Sergeev O. S. Ermakova G. N. Balandina 《Doklady Earth Sciences》2010,433(1):922-926
A new method of digital optical anemometry (Particle Image Velocimetry, PIV) of turbulent flows is suggested and implemented
in the laboratory; it is based on the use of continuous laser radiation and high-speed video photography, providing continuous
statistical ensembles of flow velocity fields. Application of the method to the study of wind field over waves has allowed
us to perform, for the first time, direct measurements of velocity fields, averaged over turbulent pulsations induced by waves
in the air flow. The experiments demonstrated that the velocity fields, averaged over the turbulent pulsations, are nonseparated
even in the case of steep and breaking waves, when separation of the flow from the wave crests in the instantaneous fields
is observed. Based on comparison with the experimental data, it is shown that the average wind fields over waves are described
well quantitatively in the framework of semiempirical closure models of turbulence. 相似文献
10.
Space spectral analysis of zonal (u) and meridional (v) components of wind and time spectral analysis of kinetic energy of zonal waves at 850 hPa during monsoon 1991 (1st June
1991 to 31st August 1991) for the global belt between equator and 40°N are investigated. Space spectral analysis shows that
long waves (wavenumbers 1 and 2) dominate the energetics of Region 1 (equator to 20°N) while over Region 2 (20°N to 40°N)
the kinetic energy of short waves (wavenumbers 3 to 10) is more than kinetic energy of long waves. It has been found that
kinetic energy of long waves is dominated by zonal component while both (zonal and meridional) the components of wind have
almost equal contribution in the kinetic energy of short waves.
Temporal variations of kinetic energy of wavenumber 2 over Region 1 and Region 2 are almost identical. The correlation matrix
of different time series shows that (i) wavenumber 2 over Regions 1 and 2 might have the same energy source and (ii) there
is a possibility of an exchange of kinetic energy between wavenumber 1 over Region 1 and short waves over Region 2. Wave to
wave interactions indicate that short waves over Region 2 are the common source of kinetic energy to wavenumber 2 over Regions
1 and 2 and wavenumber 1 over Region 1. Time spectral analysis of kinetic energy of zonal waves indicates that wavenumber
1 is dominated by 30–45 day and bi-weekly oscillations while short waves are dominated by weekly and bi-weekly oscillations.
The correlation matrix, wave to wave interaction and time spectral analysis together suggest that short period oscillations
of kinetic energy of wavenumber 1 might be one of the factors causing dominant weekly (5–9 day) and bi-weekly (10–18 day)
oscillations in the kinetic energy of short waves. 相似文献
11.
Tsunami runup and drawdown can cause liquefaction failure of coastal fine sand slopes due to the generation of high excess
pore pressure and the reduction of the effective over burden pressure during the drawdown. The region immediately seaward
of the initial shoreline is the most susceptible to tsunami-induced liquefaction failure because the water level drops significantly
below the still water level during the set down phase of the drawdown. The objective of this work is to develop and validate
a numerical model to assess the potential for tsunami-induced liquefaction failure of coastal sandy slopes. The transient
pressure distribution acting on the slope due to wave runup and drawdown is computed by solving for the hybrid Boussinesq—nonlinear
shallow water equations using a finite volume method. The subsurface pore water pressure and deformation fields are solved
simultaneously using a finite element method. Two different soil constitutive models have been examined: a linear elastic
model and a non-associative Mohr–Coulomb model. The numerical methods are validated by comparing the results with analytical
models, and with experimental measurements from a large-scale laboratory study of breaking solitary waves over a planar fine
sand beach. Good comparisons were observed from both the analytical and experimental validation studies. Numerical case studies
are shown for a full-scale simulation of a 10-m solitary wave over a 1:15 and 1:5 sloped fine sand beach. The results show
that the soil near the bed surface, particularly along the seepage face, is at risk to liquefaction failure. The depth of
the seepage face increases and the width of the seepage face decreases with increasing bed slope. The rate of bed surface
loading and unloading due to wave runup and drawdown, respectively, also increases with increasing bed slope. Consequently,
the case with the steeper slope is more susceptible to liquefaction failure due to the higher hydraulic gradient. The analysis
also suggests that the results are strongly influenced by the soil permeability and relative compressibility between the pore
fluid and solid skeleton, and that a coupled solid/fluid formulation is needed for the soil solver. Finally, the results show
the drawdown pore pressure response is strongly influenced by nonlinear material behavior for the full-scale simulation. 相似文献
12.
We simulate the propagation of ultrasonic waves in heterogeneous poroviscoelastic media saturated by immiscible fluids. Our model takes into account capillary forces and viscous and mass coupling effects between the fluid phases under variable saturation and pore fluid pressure. The numerical problem is solved in the space–frequency domain using a finite element procedure and the time–domain solution is obtained by a numerical Fourier transform. Heterogeneities due to fluid distribution and rock porosity–permeability are modeled as stochastic fractals, whose spectral densities reproduce saturation an petrophysical variations similar to those observed in reservoir rocks. The numerical experiments are performed at a central frequency of 500 kHz, and show clearly the effects of the different heterogeneities on the amplitudes of shear and compressional waves and the importance of wave mode conversions at the different interfaces. 相似文献
13.
14.
饱和半无限体表面透水性会影响表面波（瑞利波和斯通利波）存在及其传播特性。在表面透水情况下,只有瑞利波存在,而在不透水情况,不仅有瑞利波而且还有斯通利波。表面波在工程勘探及声波测试中扮演很重要角色,因此,有必要研究表面透水性对表面波传播特性的影响。采用薄层法,将表面波频率方程根的搜索问题转换成求特征值问题。根据表面波沿深度衰减特性,从一组计算的特征值及特征向量中筛选出与表面波对应特征值、特征向量,由特征值得到表面波频率特性（频散和衰减特性）,由特征向量得到孔隙压力、骨架位移随深度变化,进而分析在表面不透水情况下瑞利波和斯通利波影响深度及程度。 相似文献
15.
Trapped waves of the 27 November 1945 Makran tsunami: observations and numerical modeling 总被引：1，自引：1，他引：0
S. Neetu I. Suresh R. Shankar B. Nagarajan R. Sharma S. S. C. Shenoi A. S. Unnikrishnan D. Sundar 《Natural Hazards》2011,59(3):1609-1618
The 27 November 1945 earthquake in the Makran Subduction Zone triggered a destructive tsunami that has left important problems
unresolved. According to the available reports, high waves persisted along the Makran coast and at Karachi for several hours
after the arrival of the first wave. Long-duration sea-level oscillations were also reported from Port Victoria, Seychelles.
On the other hand, only one high wave was reported from Mumbai. Tide-gauge records of the tsunami from Karachi and Mumbai
confirm these reports. While the data from Mumbai shows a single high wave, Karachi data shows that high waves persisted for
more than 7 h, with maximum wave height occurring 2.8 h after the arrival of the first wave. In this paper, we analyze the
cause of these persistent high waves using a numerical model. The simulation reproduces the observed features reasonably well,
particularly the persistent high waves at Karachi and the single high wave at Mumbai. It further reveals that the persistent
high waves along the Makran coast and at Karachi were the result of trapping of the tsunami-wave energy on the continental
shelf off the Makran coast and that these coastally-trapped edge waves were trapped in the along-shore direction within a
∼300-km stretch of the continental shelf. Sensitivity experiments establish that this along-shore trapping of the tsunami
energy is due to variations in the shelf width. In addition, the model simulation indicates that the reported long duration
of sea-level oscillations at Port Victoria were mainly due to trapping of the tsunami energy over the large shallow region
surrounding the Seychelles archipelago. 相似文献
16.
Dolgikh G. I. Budrin S. S. Dolgikh S. G. Ovcharenko V. V. Pivovarov A. A. Samchenko A. N. Shvyrev A. N. Chupin V. A. Yaroshchuk I. O. 《Doklady Earth Sciences》2017,475(1):811-815
On the basis of experimental data obtained during a comprehensive experiment in Vityaz Bay of the Sea of Japan using onshore laser strainmeters and a low-frequency hydroacoustic emitter generating complex phase-manipulated signals with a central frequency of 33 Hz, we developed the basic principles of contactless tomography of the Earth’s crust in the shelf regions of various seas, including those covered by ice, making it possible to determine efficiently the structure and composition of the upper Earth’s crust under seas.
相似文献17.
Cyclone-generated surface waves are simulated using state-of-art SWAN (Simulating WAves Nearshore) model coupled with hydrodynamic
model inputs. A severe cyclonic storm passed over the Arabian Sea during 4–9th November 1982 is selected from UNISYS track
records. The cyclone lasted for nearly 6 days and subsided with a land fall at Gujarat coast, west coast of India. In this
study, cyclonic wind fields are generated using a well-established relationship suggested by Jelesnianski and Taylor (1973). The associated water level variations due to storm surge and surge generated currents are simulated using POM (Princeton
Ocean Model). The outputs are one-way coupled with the wave model SWAN for simulating wave parameters off Gujarat, north-east
basin of Arabian Sea. An extensive literature review is carried out on the progress and methodology adopted for storm wave
modelling and analysis. The results presented in this paper reveal the severity of the storm event and would be highly useful
for assessing the extreme wave event/climate especially for the south coast of Gujarat. 相似文献
18.
Short and high frequency internal waves, propagating through horizontal gradients of temperature formed by long and low-frequency
waves, induce vertical transferof heat with effective coefficients 10−4 – 10−3 m2/s and lead to a fine structure formation. Horizontal turbulence with seals of order 100 m produce the same effect in the
presence of internal waves. The same is true for other substances, such as salt, oxygen, organic matter. It is suggested that
this augmenting of vertical transports due to internal waves is an essential factor for high biological productivity in shelf
zones. 相似文献
19.
Chiara Biscarini 《Landslides》2010,7(2):117-124
This paper describes the application of detailed computational fluid dynamics (CFD) to simulate the formation and propagation
of waves generated by the impact of landslide material with water. The problem is schematised as a multiphase–multicomponent
fluid flow: compressible air, water and transported alluvial material. The landslide simulation is performed by means of a
hybrid approach: as a rigid solid body slipping down along an inclined slope until it starts penetrating the water body. The
CFD model solves the Navier–Stokes equations with the RNG k-ɛ turbulence closure scheme and the volume of fluid multiphase
method, which maintains the interface as a sharp front. The governing equations are solved using the commercial CFD code,
FLUENT. The computed results are compared with experimental data reported in the literature. The model is then applied to
simulate the 1958 Lituya bay Tsunami event with a 2D a simplified geometry and the results are compared to others found in
literature. 相似文献
20.
Diffusion profiles in minerals are increasingly used to determine the duration of geological events. For this purpose, the
distinction between growth and diffusion zoning is critical; it requires the understanding of complex features associated
with multicomponent diffusion. Seed-overgrowth interdiffusion experiments carried out in the range 1,050–1,250°C at 1.3 GPa
have been designed to quantify and better understand Fe–Mg–Ca interdiffusion in garnet. Some of the diffusion profiles measured
by analytical transmission electron microscope show characteristic features of multicomponent diffusion such as uphill diffusion,
chemical solitary waves, zero-flux planes and complex diffusion paths. We implemented three different methods to calculate
the interdiffusion coefficients of the D matrix from the experimental penetration curves and determined that with Ca as the dependent component, the crossed coefficients
of the D matrix are negative. Experiments and numerical simulations indicate that: (1) uphill diffusion in garnet can be observed
indifferently on the three components Fe, Mg and Ca, (2) it takes the form of complementary depletion/repletion waves and
(3) chemical waves occur preferentially on initially flat concentration profiles. Derived D matrices are used to simulate the fate of chemical waves in time, in finite crystals. These examples show that the flow of
atoms in multicomponent systems is not necessarily unidirectional for all components; it can change both in space along the
diffusion profile and in time. Moving zero-flux planes in finite crystals are transitory features that allow flux reversals
of atoms in the diffusion zone. Interdiffusion coefficients of the D matrices are also analyzed in terms of eigenvalues and eigenvectors. This analysis and the experimental results show that
depending on the composition of the diffusion couple, (1) the shape of chemical waves and diffusion paths changes; (2) the
width of the diffusion zone for each component may or may not be identical; and (3) the width of diffusion calculated at a
given D and duration may greatly vary. D matrices were retrieved from thirteen sets of diffusion profiles. Data were cast in Arrhenius relations. Linear regressions
of the data yield activation energies equal to 368, 148, 394, 152 kJ mol−1 at 1 bar and frequency factors Do equal to 2.37 × 10−6, −4.46 × 10−16, −1.31 × 10−5, 9.85 × 10−15 m2 s−1 for [(D)\tilde]FeFeCa \tilde{D}_{FeFe}^{Ca} , [(D)\tilde]FeMgCa \tilde{D}_{FeMg}^{Ca} , [(D)\tilde]MgFeCa \tilde{D}_{MgFe}^{Ca} , [(D)\tilde]MgMgCa \tilde{D}_{MgMg}^{Ca} , respectively. These values can be used to calculate interdiffusion coefficients in Fe–Mg–Ca garnets and determine the duration
of geological events in high temperature metamorphic or magmatic garnets. 相似文献