A Stochastic Approach in Estimating the Pseudo-Relative Spectral Velocity

1998 ◽  
Vol 14 (2) ◽  
pp. 301-317 ◽  
Author(s):  
Li Jun Liu ◽  
Shahram Pezeshk
Keyword(s):  
Ground Motion ◽  
Gaussian White Noise ◽  
Stochastic Approach ◽  
Gaussian Stationary Process ◽  
Spectral Velocity ◽  
Seismological Model ◽  
Pseudo Spectral ◽  
Amplitude Level ◽  
Motion Amplitude ◽  
Good Agreement

In the prediction of ground motion from seismological model by random vibration theory, the basic assumption as that the ground motion process is a bandlimited Gaussian white noise (BGWN). For pseudo-response spectral values, the estimation is based on the response of a single-degree-of-freedom (SDOF) system due to the input of BGWN. The function of an SDOF is a narrowband filter. Therefore, the response of an SDOF is a narrowband process that no longer satisfies the assumption of bandlimited random process. The property of a narrowband process is significantly different from that of a bandlimited process and should be incorporated into the estimation of pseudo-spectral values. A stochastic methodology is proposed to estimate the spectral values on the basis of narrowband Gaussian stationary process. A key feature of the method is the use of envelope crossings in lieu of press crossings of the ground motion amplitude level. This substitution makes the estimation of spectral values more accurate. Comparing our results with those of previous research studies, we will illustrate that our proposed approach is in a good agreement with that of the simulation of time domain.

Strong Ground Motion Prediction Model for PGV and Spectral Velocity for the Chilean Subduction Zone

2021 ◽  
Author(s):  
Gonzalo A. Montalva ◽  
Nicolás Bastías ◽  
Felipe Leyton
Keyword(s):  
Subduction Zone ◽  
Ground Motion ◽  
Fundamental Frequency ◽  
Spectral Response ◽  
Motion Prediction ◽  
Slight Reduction ◽  
Ground Motion Prediction ◽  
Proposed Model ◽  
Strong Ground Motion Prediction ◽  
Spectral Velocity

ABSTRACT Ground-motion prediction models (GMPMs) are a critical tool in performing seismic hazard analyses; in turn, these studies condition structural designs. Consequently, new research has appeared not only with a regionalization focus but has also explored the prediction of intensities other than acceleration. We present a GMPM for peak ground velocity (PGV) and spectral velocity (Sv) for the Chilean subduction zone. Because of the limitations of VS30 as site proxy, the proposed model adds the site’s fundamental frequency (f0) as an explanatory variable for the site term in the GMPM. We developed the model for PGV and spectral response periods between 0.06 and 10 s. The total error (σ) of the model shows a slight reduction with the inclusion of the fundamental frequency (f0) compared with a similar model for the pseudoacceleration response spectrum in the same zone. We used the proposed model to predict structural damage during the 2010 Mw 8.8 Maule earthquake, showing a good fit with the geographical distribution of damage, and this creates an opportunity to characterize the seismic behavior of soil deposits, including basins, for urban planning.

Relational database used for ground-motion model development in the NGA-sub project

2021 ◽  
pp. 875529302110552
Author(s):  
Silvia Mazzoni ◽  
Tadahiro Kishida ◽  
Jonathan P Stewart ◽  
Victor Contreras ◽  
Robert B Darragh ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Ground Motion ◽  
Data Storage ◽  
Relational Database ◽  
Model Development ◽  
Intensity Measures ◽  
Motion Models ◽  
Ground Motion Model ◽  
Ground Motion Models ◽  
Pseudo Spectral

The Next-Generation Attenuation for subduction zone regions project (NGA-Sub) has developed data resources and ground motion models for global subduction zone regions. Here we describe the NGA-Sub database. To optimize the efficiency of data storage, access, and updating, data resources for the NGA-Sub project are organized into a relational database consisting of 20 tables containing data, metadata, and computed quantities (e.g. intensity measures, distances). A database schema relates fields in tables to each other through a series of primary and foreign keys. Model developers and other users mostly interact with the data through a flatfile generated as a time-stamped output of the database. We describe the structure of the relational database, the ground motions compiled for the project, and the means by which the data can be accessed. The database contains 71,340 three-component records from 1880 earthquakes from seven global subduction zone regions: Alaska, Central America and Mexico, Cascadia, Japan, New Zealand, South America, and Taiwan. These data were processed on a component-specific basis to minimize noise effects in the data and remove baseline drifts. Provided ground motion intensity measures include peak acceleration, peak velocity, and 5%-damped pseudo-spectral accelerations for a range of oscillator periods.

Numerical Modeling of Near Fault Seismic Ground Motion for Denali Fault

2021 ◽  
Vol 12 (2) ◽  
pp. 0-0
Keyword(s):  
Ground Motion ◽  
Peak Ground Acceleration ◽  
Numerical Study ◽  
Ground Motions ◽  
Numerical Results ◽  
Fault Rupture ◽  
Ground Acceleration ◽  
Denali Fault ◽  
Near Fault ◽  
Good Agreement

An effective earthquake (Mw 7.9) struck Alaska on 3 November, 2002. This earthquake ruptured 340 km along Susitna Glacier, Denali and Totschunda faults in central Alaska. The peak ground acceleration (PGA) was recorded about 0.32 g at station PS10, which was located 3 km from the fault rupture. The PGA would have recorded a high value, if more instruments had been installed in the region. A numerical study has been conducted to find out the possible ground motion record that could occur at maximum horizontal slip during the Denali earthquake. The current study overcomes the limitation of number of elements to model the Denali fault. These numerical results are compared with observed ground motions. It is observed that the ground motions obtained through numerical analysis are in good agreement with observed ground motions. From numerical results, it is observed that the possible expected PGA is 0.62 g at maximum horizontal slip of Denali fault.

Evaluation of Earthquake Response Spectra Directionality Using Stochastic Simulations

2021 ◽  
Author(s):  
Alan Poulos ◽  
Eduardo Miranda ◽  
Jack W. Baker
Keyword(s):  
Stochastic Process ◽  
Ground Motion ◽  
Ground Motions ◽  
Gaussian White Noise ◽  
Response Spectra ◽  
Orientation Dependence ◽  
Stochastic Simulations ◽  
Earthquake Ground Motion ◽  
Significant Duration ◽  
Simulated Ground Motions

ABSTRACT For earthquake-resistant design purposes, ground-motion intensity is usually characterized using response spectra. The amplitude of response spectral ordinates of horizontal components varies significantly with changes in orientation. This change in intensity with orientation is commonly known as ground-motion directionality. Although this directionality has been attributed to several factors, such as topographic irregularities, near-fault effects, and local geologic heterogeneities, the mechanism behind this phenomenon is still not well understood. This work studies the directionality characteristics of earthquake ground-motion intensity using synthetic ground motions and compares their directionality to that of recorded ground motions. The two principal components of horizontal acceleration are sampled independently using a stochastic model based on finite-duration time-modulated filtered Gaussian white-noise processes. By using the same stochastic process to sample both horizontal components of motion, the variance of horizontal ground acceleration has negligible orientation dependence. However, these simulations’ response spectral ordinates present directionality levels comparable to those found in real ground motions. It is shown that the directionality of the simulated ground motions changes for each realization of the stochastic process and is a consequence of the duration being finite. Simulated ground motions also present similar directionality trends to recorded earthquake ground motions, such as the increase of average directionality with increasing period of vibration and decrease with increasing significant duration. These results suggest that most of the orientation dependence of horizontal response spectra is primarily explained by the finite significant duration of earthquake ground motion causing inherent randomness in response spectra, rather than by some physical mechanism causing polarization of shaking.

scholarly journals Laguerre–Hermite pseudo-spectral velocity formulation of gyrokinetics

2018 ◽  
Vol 84 (1) ◽  
Author(s):  
N. R. Mandell ◽  
W. Dorland ◽  
M. Landreman
Keyword(s):  
Three Dimensional ◽  
Collision Operator ◽  
Zonal Flow ◽  
Phase Mixing ◽  
Final Model ◽  
Nonlinear Phase ◽  
Wide Range ◽  
H Theorem ◽  
Spectral Velocity ◽  
Pseudo Spectral

First-principles simulations of tokamak turbulence have proven to be of great value in recent decades. We develop a pseudo-spectral velocity formulation of the turbulence equations that smoothly interpolates between the highly efficient but lower resolution three-dimensional (3-D) gyrofluid representation and the conventional but more expensive 5-D gyrokinetic representation. Our formulation is a projection of the nonlinear gyrokinetic equation onto a Laguerre–Hermite velocity-space basis. We discuss issues related to collisions, closures and entropy. While any collision operator can be used in the formulation, we highlight a model operator that has a particularly sparse Laguerre–Hermite representation, while satisfying conservation laws and the H theorem. Free streaming, magnetic drifts and nonlinear phase mixing each give rise to closure problems, which we discuss in relation to the instabilities of interest and to free energy conservation. We show that the model is capable of reproducing gyrokinetic results for linear instabilities and zonal flow dynamics. Thus the final model is appropriate for the study of instabilities, turbulence and transport in a wide range of geometries, including tokamaks and stellarators.

Ground Motion Synthesis and Seismic Scenario in Guwahati City--A Stochastic Approach

2009 ◽  
Vol 80 (2) ◽  
pp. 233-242 ◽  
Author(s):  
S. K. Nath ◽  
A. Raj ◽  
K. K. S. Thingbaijam ◽  
A. Kumar
Keyword(s):  
Ground Motion ◽  
Stochastic Approach ◽  
Motion Synthesis ◽  
Guwahati City

INFLUENCE OF NUCLEAR DISSIPATION ON PRESCISSION NEUTRON MULTIPLICITY, FISSION PROBABILITY AND FISSION TIME FOR COMPOUND NUCLEUS 210Po

2012 ◽  
Vol 21 (01) ◽  
pp. 1250008 ◽  
Author(s):  
H. ESLAMIZADEH
Keyword(s):  
Compound Nucleus ◽  
Stochastic Approach ◽  
Neutron Multiplicity ◽  
Langevin Equations ◽  
Excitation Energies ◽  
One Dimensional ◽  
Reduction Coefficient ◽  
Fission Probability ◽  
Nuclear Dissipation ◽  
Good Agreement

A stochastic approach for fission dynamics based on one-dimensional Langevin equations was applied to investigate the effect of the nuclear dissipation on the prescission neutron multiplicity, fission probability and the fission time for the compound nucleus 210 Po in an intermediate range of excitation energies 30–120 MeV. A modified wall and window dissipation with a reduction coefficient, k s , has been used in the Langevin equations. It was shown that the results of the calculations are in good agreement with the experimental data by using values of k s in the range 0.28 ≤ k s ≤ 0.50.

The Case for Using Mean Seismic Hazard

2005 ◽  
Vol 21 (3) ◽  
pp. 879-886 ◽  
Author(s):  
Robin K. McGuire ◽  
C. Allin Cornell ◽  
Gabriel R. Toro
Keyword(s):  
Decision Making ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Cost Benefit Analysis ◽  
Cost Benefit ◽  
Probabilistic Seismic Hazard ◽  
Benefit Analysis ◽  
Annual Frequency ◽  
The Mean ◽  
Motion Amplitude

Complete probabilistic seismic hazard analyses incorporate epistemic uncertainties in assumptions, models, and parameters, and lead to a distribution of annual frequency of exceedance versus ground motion amplitude (the “seismic hazard”). For decision making, if a single representation of the seismic hazard is required, it is always preferable to use the mean of this distribution, rather than some other representation, such as a particular fractile. Use of the mean is consistent with modern interpretations of probability and with precedents of safety goals and cost-benefit analysis.

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