Extension of the Basin Rayleigh-Wave Amplification Theory to Include Basin-Edge Effects

2020 ◽  
Vol 110 (3) ◽  
pp. 1305-1322
Author(s):  
Quentin Brissaud ◽  
Daniel C. Bowden ◽  
Victor C. Tsai
Keyword(s):  
Rayleigh Wave ◽  
Edge Effects ◽  
Resonance Effect ◽  
Slope Angle ◽  
Computational Cost ◽  
Site Amplification ◽  
Coupling Coefficients ◽  
Wave Amplification ◽  
Wave Basin ◽  
Basin Edge

ABSTRACT The presence of sediments near the Earth’s surface can significantly amplify the strength of shaking during earthquakes. Such basin or site amplification effects have been well documented in numerous regions, yet the complex and often situational dependence of competing reasons for this amplification makes it hard to quantify in a general sense or to determine the most significant contributions. Simple 1D seismic profiles can be used to estimate the amplitude differences between a basin site and a hard-rock reference site, but this ignores any reflections or conversions at the basin edge or a resonance effect depending on the basin’s geometry. In this article, we explore an analytic model based on coupling coefficients for surface Rayleigh waves to account for the lateral discontinuities at a basin’s edge (Datta 2018). We use this simple tool to explore the relationship between the basin’s Rayleigh-wave amplification spectrum and various parameters such as basin depth, edge slope angle, and impedance contrast. The step-by-step construction of the model allows us to quantify the contributions from various wave propagation effects with the goal of identifying situations under which various basin-edge effects must be considered in addition to purely 1D estimates. For the most velocity contrasts (less than a factor of 5), the error made by the 1D theory in predicting maximum Rayleigh-wave basin amplification is under 35% for both the horizontal and the vertical components. For simple basins, the vertical amplification dominates at larger high frequencies and the horizontal at lower frequencies. Finally, we demonstrate from comparisons with spectral-element wavefield simulations that realistic velocity structures can be reduced to a simpler “box” shape for the semi-analytic formulation used here with reasonable results. For the purposes of estimating site-amplification or microzonation, an improved model that accounts for basin-edge effects can be implemented without high-computational cost.

Spatial variations in seismic motions

1976 ◽  
Vol 3 (1) ◽  
pp. 32-46
Author(s):  
G. P. Nair ◽  
J. J. Emery
Keyword(s):  
Rayleigh Wave ◽  
Epicentral Distance ◽  
Soil Layer ◽  
Focal Depth ◽  
Spatial Variations ◽  
Angle Of Incidence ◽  
Layer System ◽  
Wave Amplification ◽  
Wave Phase Velocity ◽  
Rayleigh Wave Phase Velocity

A method for evaluating the spatial variations in strong seismic motions for a linear, homogeneous, and horizontally stratified soil layer system is presented. The procedure accounts for the focal depth and the epicentral distance, the corresponding angle of incidence, and the relative contributions of both shear and Rayleigh waves. The inclined propagation of shear waves is studied using the multiple reflection refraction theory. The range of possible values of Rayleigh wave phase velocity in the soil layer system is determined, and using an averaging procedure the Rayleigh wave amplification factors are computed. The influences of various factors on the spatial variations in seismic response are discussed. The method is general so that it can be used for various problems involving spatial motion computations. The application of the method in computing the responses of a soil–pile system is described and some typical results given.

scholarly journals Joint Angles and Mutual Coupling Estimation Algorithm for Bistatic MIMO Radar

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Jianfeng Li ◽  
Xiaofei Zhang
Keyword(s):  
Mutual Coupling ◽  
Multiple Input Multiple Output ◽  
Computational Cost ◽  
Estimation Algorithm ◽  
Mimo Radar ◽  
Coupling Coefficients ◽  
Angle Estimation ◽  
One Dimensional ◽  
Input Multiple Output ◽  
The One

We study the problem of angle estimation for a bistatic multiple-input multiple-output (MIMO) radar with unknown mutual coupling and proposed a joint algorithm for angles and mutual coupling estimation with the characteristics of uniform linear arrays and subspaces exploitation. We primarily obtain an initial estimate of DOA and DOD, then employ the local one-dimensional searching to estimate exactly DOA and DOD, and finally evaluate the parameters of mutual coupling coefficients via the estimated angles. Exploiting twice of the one-dimensional local searching, our method has much lower computational cost than the algorithm in (Liu and Liao (2012)), and automatically obtains the paired two-dimensional angle estimation. Slightly better performance for angle estimation has been achieved via our scheme in contrast to (Liu and Liao (2012)), while the two methods indicate very close performance of mutual coupling estimation. The simulation results verify the algorithmic effectiveness of our scheme.

Observations of Rayleigh waves in Mexico City Valley during the 19 September 2017 Puebla–Morelos, Mexico earthquake

2020 ◽  
Vol 36 (2_suppl) ◽  
pp. 62-82
Author(s):  
Pablo Heresi ◽  
Jorge Ruiz-García ◽  
Omar Payán-Serrano ◽  
Eduardo Miranda
Keyword(s):  
Surface Waves ◽  
Mexico City ◽  
Edge Effects ◽  
Rayleigh Waves ◽  
Soft Soil ◽  
Inner Product ◽  
Basin Edge ◽  
Literature Evidence ◽  
Mexico Earthquake ◽  
Stockwell Transform

This article discusses the principal features of Rayleigh surface waves generated by basin-edge effects in Mexico City during the Mw7.1 19 September 2017 Puebla–Morelos, Mexico earthquake. Rayleigh waves were extracted from ground motions recorded at 12 stations in Mexico City. We used a recently proposed method for extracting surface waves, where the earthquake record is filtered based on the normalized inner product of the Stockwell transform of the three-component earthquake recordings. Results of this study reveal that basin-edge effects produced strong Rayleigh waves, particularly at certain stations, with frequencies that are mainly between 0.2 and 0.9 Hz, which is consistent with previous frequency ranges reported in the literature. Evidence of higher-mode Rayleigh waves was found at all stations located on soft soil sites, even at stations that are more than 1 km away from the basin edges. It was also observed that peak acceleration spectral ordinates of the retrograde component of the extracted Rayleigh waves at two stations exceeded the design spectral ordinates of the 1976 and 2004 editions of the Mexico City Seismic Provisions.

scholarly journals BIFURCATIONS OF STEADY STATES OF THE BIAXIAL CREW MODEL

2019 ◽  
pp. 59-71
Author(s):  
V. G. Verbytsky ◽  
A. I. Bezverkhy ◽  
I. V. Tsidylo ◽  
V. M. Senchishak
Keyword(s):  
Symmetric Solution ◽  
Computational Cost ◽  
Transport Systems ◽  
Steering Wheel ◽  
Neutral Position ◽  
Coupling Coefficients ◽  
Linear System Of Equations ◽  
Straight Line ◽  
Left And Right ◽  
The Stability

Many transport systems (car, airplane, ship) have symmetry property. For such systems symmetrical deviations of some control parameter (steering wheel) from the neutral position lead to symmetry of the dynamic behaviour of the object (equivalence of left and right turns). In this case the straight-line motion of an object with constant velocity corresponds to a trivial solution of the corresponding dynamic system (symmetric solution). Conditions for dangerous-safe loss of symmetric junction stability (the case of one zero proper linear approximation system) can be obtained from the analysis of the true birth-fusion of stationary states with a stationary state corresponding to a symmetric solution. This approach makes it possible to obtain conditions of dangerous and safe loss of symmetric junction stability equivalent to the conditions of MM. Bautin [3] with the lowest possible computational cost. The proposed approach is illustrated by the example of the stability analysis of a nonlinear model of a double-axle crew with excessive rotation. It is shown that the condition of hazardous and safe loss of stability of straight-line motion (symmetric junction) is determined by the ratio between dimensionless coefficients of axle deflection and coupling coefficients on transaxle axes. However, clutch coefficients are not included in the linear system of equations of perturbed motion but refer to a substantially nonlinear characteristic of the forces of withdrawal.

scholarly journals Prediction and Validation of Landing Stability of a Lunar Lander by a Classification Map Based on Touchdown Landing Dynamics’ Simulation Considering Soft Ground

Aerospace ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 380
Author(s):  
Yeong-Bae Kim ◽  
Hyun-Jae Jeong ◽  
Shin-Mu Park ◽  
Jae Hyuk Lim ◽  
Hoon-Hee Lee
Keyword(s):  
Friction Coefficient ◽  
Soft Soil ◽  
Slope Angle ◽  
Computational Cost ◽  
Dynamics Simulation ◽  
Soft Ground ◽  
Fe Model ◽  
Machine Learning Classification ◽  
Lunar Lander ◽  
Stable Sliding

In this paper, a method for predicting the landing stability of a lunar lander by a classification map of the landing stability is proposed, considering the soft soil characteristics and the slope angle of the lunar surface. First, the landing stability condition in terms of the safe (=stable), sliding (=unstable), and tip-over (=statically unstable) possibilities was checked by dropping a lunar lander onto flat lunar surfaces through finite-element (FE) simulation according to the slope angle, friction coefficient, and soft/rigid ground, while the vertical touchdown velocity was maintained at 3 m/s. All of the simulation results were classified by a classification map with the aid of logistic regression, a machine-learning classification algorithm. Finally, the landing stability status was efficiently predicted by Monte Carlo (MC) simulation by just referring to the classification map for 10,000 input datasets, consisting of the friction coefficient, slope angles, and rigid/soft ground. To demonstrate the performance, two virtual lunar surfaces were employed based on a 3D terrain map of the LRO mission. Then, the landing stability was validated through landing simulation of an FE model of a lunar lander requiring high computation cost. The prediction results showed excellent agreement with those of landing simulations with a negligible computational cost of around a few seconds.

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