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Wave Propagation in Two-Dimensional Isotropic Waveguides
Published in Srinivasan Gopalakrishnan, Elastic Wave Propagation in Structures and Materials, 2023
The propagation of P-waves and S-waves has great relevance to those engaged in earthquake engineering research. The P-wave motion is same as that of sound wave in air, that is, it alternately pushes (compresses) and pulls (dilates) the structure. The motion of the particles is always in the direction of propagation. This wave, like sound, travels both in solids and fluids. It may be mentioned that, because of sound like nature, when P-wave emerges from deep in the Earth to the surface, a fraction of it is transmitted into atmosphere as sound waves. Such sounds, if frequency is greater than 15 cycles per second, are audible to animals or human beings. These are known as Earthquake Sound. The pictorially, the propagation of P-waves and S-waves is shown in Fig. 7.2.
Application of P and SH waves high resolution seismic reflection prospecting to investigation of unstable areas
Published in Jan Rybář, Josef Stemberk, Peter Wagner, Landslides, 2018
M.L. Rainone, P. Signanini, V. D’Intinosante
In the discussed examples it has been possible to verify the good results obtained by high resolution seismic reflection prospecting applied to the investigation of landslides areas. It is important to emphasize as the P waves use can be applied in the presence of a strong difference of seismic impedance between the surface deposits and bedrock (like in Lodrone landslides) or, more generally, when the investigated area is characterised by the presence of lithoid materials while SH waves give better results in porous media as clay, silty and sands and, generally when the difference of seismic (rigidity) is not high. High covereges are not necessary. In this kind of seismic techniques application, in our opinion and on the bases of the obtained results, we think that is more important to use short intergeophonic distance and short offset.
In-Line Metrology
Published in Robert Doering, Yoshio Nishi, Handbook of Semiconductor Manufacturing Technology, 2017
A brief description of elliptically polarized light and the phenomena of reflection and refraction facilitates the discussion of ellipsometry given below [43,44]. In Figure 24.24, a wave of light that is linearly polarized parallel to the plane of incidence to the sample surface is shown reflecting at an angle φ. This wave is designated a “p” wave. Light that is polarized perpendicular to the plane of incidence is designated as “s” waves. When “p” and “s” waves are combined slightly out of phase, the light beam is elliptically polarized. If the phase difference is 90°, the light is circularly polarized. In Figure 24.25, light is shown reflecting from an infinitely thick sample with complex index of refraction N2= n – ik where k is the extinction coefficient. The extinction coefficient is related to the adsorption coefficient of light, α, through the following relationship: k=λ4παandI(z)=I0e−αzI(z) is the intensity of light at a depth z below the sample surface, and 10 is the initial intensity of light that enters the sample.
Semi-automated template matching and machine-learning based analysis of the August 2020 Castelsaraceno microearthquake sequence (southern Italy)
Published in Geomatics, Natural Hazards and Risk, 2023
S. Panebianco, V. Serlenga, C. Satriano, F. Cavalcante, T. A. Stabile
The term x is the mean epicentral distance calculated as the average epicentral distance of all the stations from the mainshock; VS and QS are the average S-wave velocity and quality factor of the area, set equal to 3.4 km/s (Improta et al. 2017) and 200 (Amoroso et al. 2017), respectively. With a similar approach the t* bounds of the inversion grid (t*min, t*max) were estimated equal to 0.01 and 0.085, respectively, given by: where xmin and xmax are the minimum (12 km, SARCL) and maximum (44 km, PGN3) station epicentral distance from the earthquake, respectively; QS,min and QS,max are the minimum and maximum S-wave quality factor estimated for the area equal to 150 and 300, respectively (Amoroso et al. 2017). Finally, we assumed a crustal density of 2700 kg/m3 and a P-wave velocity (VP) of 6.5 km/s (Improta et al. 2017). We defined the seismic moment inversion bounds in terms of the respective moment magnitude (MW) bounds allowing a variability of 0.35 around the initial value. The fc bounds were automatically set by the inversion code.
Effect of Soil Properties and Input Motion on Site Amplification Using Validated Nonlinear Soil Model
Published in Nuclear Technology, 2021
Samyog Shrestha, Efe G. Kurt, Kyungtae Kim, Arun Prakash, Ayhan Irfanoglu
When an earthquake occurs, compressional waves and shear waves, i.e., P-waves and S-waves, respectively, are generated that travel through the interior of the earth. P-waves cause particles to move parallel to the direction of wave propagation whereas S-waves cause shearing deformation as they travel through a material. The velocities at which these waves travel in different soil layers are required to model soil behavior under compression and shear loading. S-wave and P-wave velocity profiles and acceleration time series recorded during different earthquakes are available in the KiK-net database. Acceleration data are recorded by the strong motion accelerometers installed at the base of the borehole and at the ground surface of each station. Table I shows the sites and details of the input motions including date of earthquake, moment magnitude, epicentral distance, and peak surface acceleration considered for validation of the benchmark numerical soil column model in MASTODON. Figure 2 shows locations of the selected sites and epicenters of the earthquakes considered. Three-component ground motion recorded during the event dated 11/22/2016 for the Iwaki-E (FKSH14) downhole array site is shown in Fig. 3.
Coupled Horizontal and Vertical Component Analysis of Strong Ground Motions for Soil–Pile–Superstructure Systems: Application to a Bridge Pier with Soil–Structure Interaction
Published in Journal of Earthquake Engineering, 2021
Ahmad Dehghanpoor, David Thambiratnam, Tommy Chan, Ertugrul Taciroglu, George Kouretzis, Zheng Li
Towards achieving the second objective, the soil plasticity model is validated for horizontal ground motion in Section 3.2, and the results are presented in Figure 4b. In this section, the vertical site response analysis as presented in Tsai and Liu [2017] is applied for achieving Objective (ii), which investigates the shear modulus reduction and damping ratio curves for compressional wave propagation. It should be noted that the above-mentioned analytical solution (Eq. (8)) is only capable of considering a uniform damped soil deposit with a constant hysteretic damping ratio. Therefore, to validate soil nonlinearity effects in the numerical model, a site response analysis is required for vertical ground motion to explore stiffness degradation and hysteretic damping curves. A common engineering practice is to substitute the P-wave velocity with the shear wave velocity in site response analyses. However, recent studies [Bozorgnia and Campbell, 2016; Bradley et al., 2014; Stewart et al., 2016] have indicated that free-field motions are different for VCs and HCs of strong ground motions because of different nonlinear behaviour in the horizontal and vertical directions. Thus, in this study, a general procedure is presented to conduct equivalent linear site response analysis in the nonlinear framework for the vertical direction to validate an FE numerical model that is capable of exploring stiffness degradation and hysteretic damping curves.