Seismic wave propagation in a porous medium

Geophysics ◽  
1985 ◽  
Vol 50 (10) ◽  
pp. 1556-1565 ◽  
Author(s):  
V. de la Cruz ◽  
T. J. T. Spanos
Keyword(s):  
Porous Medium ◽  
Seismic Wave ◽  
Low Frequency ◽  
Seismic Wave Propagation ◽  
Volume Averaging ◽  
Physical Parameters ◽  
Order Of Magnitude ◽  
Complete Set ◽  
Rotational Waves ◽  
Wave Phenomena

A complete set of equations to describe low‐frequency seismic wave phenomena in fluid‐filled porous media is presented. The approach is based on the mathematics of volume‐averaging, aided by order‐of‐magnitude and physical arguments. The results are immediately utilizable by practicing seismologists. Our equations and those of Biot (1956a) are found to be largely consistent in form, and we suggest how Biot’s parameters may be defined in terms of basic physical parameters. The theory predicts two dilatational waves and two rotational waves. Under certain conditions these behave differently than would be expected on the basis of Biot’s theory.

Numerical simulation of seismic waves in porous media components

2021 ◽  
Vol 9 (1) ◽  
pp. 4-30
Author(s):  
M. Azeredo ◽  
◽  
V. Priimenko ◽  
Keyword(s):  
Numerical Simulation ◽  
Porous Medium ◽  
High Frequency ◽  
Seismic Waves ◽  
Computational Algorithm ◽  
Low Frequency ◽  
Physical Parameters ◽  
Mathematical Algorithm ◽  
Biot Equations ◽  
Attenuation And Dispersion

This work presents a mathematical algorithm for modeling the propagation of poroelastic waves. We have shown how the classical Biot equations can be put into Ursin’s form in a plane-layered 3D porous medium. Using this form, we have derived explicit for- mulas that can be used as the basis of an efficient computational algorithm. To validate the algorithm, numerical simulations were performed using both the poroelastic and equivalent elastic models. The results obtained confirmed the proposed algorithm’s reliability, identify- ing the main wave events in both low-frequency and high-frequency regimes in the reservoir and laboratory scales, respectively. We have also illustrated the influence of some physical parameters on the attenuation and dispersion of the slow wave.

The effect of Yucca Fault on seismic wave propagation

1971 ◽  
Vol 61 (3) ◽  
pp. 697-706 ◽  
Author(s):  
Walter W. Hays ◽  
John R. Murphy
Keyword(s):  
Wave Propagation ◽  
Seismic Wave ◽  
Seismic Waves ◽  
Low Frequency ◽  
Test Site ◽  
Seismic Wave Propagation ◽  
Nevada Test Site ◽  
Basement Rocks ◽  
Geological Discontinuity ◽  
Frequency Components

abstract Yucca Fault is a major structural feature of Yucca Flat, a well-known geological province of the Nevada Test Site (NTS). The trace of the Fault extends north-south over a distance of about 32 km. The fault plane is nearly vertical and offsets Quaternary alluvium, Tertiary volcanic tuffs and pre-Cenozoic basement rocks (quartzites, shales and dolomites) with relative down displacement of several hundred feet on the east side of the fault. Data recorded from the CUP underground nuclear detonation in Yucca Flat typify the effect of the fault on near-zone (i.e., inside 10 km) seismic wave propagation. The effect of the fault is frequency dependent. It affects the frequency components (3.0, 5.0, 10.0 Hz) of the seismic waves which have characteristic wavelengths in the order of the geological discontinuity. Little or no effect is observed for low-frequency components (0.5, 1.0 Hz) which have wave-lengths exceeding the dimensions of the geological discontinuity. The effect of the fault does not represent a safety problem.

Wave Field of Porous Medium Saturated by Two Immiscible Fluids Under Excitation of Multiple Wave Sources

2006 ◽  
Author(s):  
Liming Dai ◽  
Guoqing Wang
Keyword(s):  
Porous Medium ◽  
Wave Propagation ◽  
Wave Field ◽  
Low Frequency ◽  
Seismic Wave Propagation ◽  
Immiscible Fluids ◽  
Polar Coordinates ◽  
Energy Sources ◽  
Hankel Function ◽  
Multiple Wave

Wave propagation in porous medium saturated by immiscible fluids has received significant interests from the researchers in searching for comprehensively understanding the behavior of underground motion such as seismic wave propagation and artificial vibration in oil or gas reservoirs. In this research, the wave field of a porous medium saturated by two immiscible fluids is investigated. The elastic domain considered is excited by multiple cylindrical energy sources. The wave field of the whole domain with the excitation of several fast compressible waves in low frequency range is considered. Polar coordinates are utilized for the need of describing the multi-energy sources, so that the propagating waves can be expressed with the utilization of Hankel function. A moving-coordinate method is employed to study the coupling of multiple waves. The combined effects from several sources on the wave propagation are investigated and comparison with that of a single phase fluid is also addressed. With the employment of the methodology established, the wave field at any desired domain considered can be quantitatively determined in terms of wave propagation, frequencies and amplitudes of the source waves. To demonstrate the implementation of the model developed in this research, a numerical simulation is provided. The results of this research contribute to the comprehension of liquids and solid interaction under the excitation of waves, such as seismic, electromagnetic and other artificial vibrations.

scholarly journals Modelling high-frequency seismograms at ocean bottom seismometers: effects of heterogeneous structures on source parameter estimation for small offshore earthquakes and shallow low-frequency tremors

2020 ◽  
Vol 223 (3) ◽  
pp. 1708-1723
Author(s):  
Shunsuke Takemura ◽  
Suguru Yabe ◽  
Kentaro Emoto
Keyword(s):  
Wave Propagation ◽  
Parameter Estimation ◽  
Seismic Wave ◽  
High Frequency ◽  
Source Parameters ◽  
Low Frequency ◽  
Accretionary Prism ◽  
Seismic Wave Propagation ◽  
Source Parameter ◽  
Seismic Events

SUMMARY The source characteristics of offshore seismic events, especially regular (or fast) and slow earthquakes, can provide key information on their source physics and frictional conditions at the plate boundary. Due to strong 3-D heterogeneities in offshore regions, such as those relating to sea water, accretionary prism and small-scale velocity heterogeneity, conventional methods using a 1-D earth model may mis-estimate source parameters such as the duration and radiation energy. Estimations could become severe inaccuracies for small offshore seismic events because high-frequency (>1 Hz) seismograms, which are strongly affected by 3-D heterogeneities, are only available for analysis because of their signal-to-noise ratio. To investigate the effects of offshore heterogeneities on source parameter estimation for small seismic events, we analysed both observed and simulated high-frequency seismograms southeast off the Kii Peninsula, Japan, in the Nankai subduction zone. Numerical simulations of seismic wave propagation using a 3-D velocity structure model clarified the effects of each heterogeneity. Comparisons between observations and model simulations demonstrated that the thick low-velocity accretionary prism has significant effects on high-frequency seismic wave propagation. Especially for shallow low-frequency tremors occurring at depths just below the accretionary prism toe, seismogram durations are significantly broader than an assumed source duration, even for stations with epicentral distances of approximately 10 km. Spindle-shape seismogram envelopes were observed even at such close stations. Our results suggest that incorporating 3-D heterogeneities is necessary for practical estimation of source parameters for small offshore events.

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