Scaling relations for strong ground motion in large earthquakes

1982 ◽  
Vol 72 (6A) ◽  
pp. 1903-1909
Author(s):  
C. H. Scholz
Keyword(s):  
Stress Drop ◽  
Strong Ground Motion ◽  
Ground Motions ◽  
Scaling Relations ◽  
Square Root ◽  
Peak Acceleration ◽  
Particle Velocities ◽  
Large Earthquakes ◽  
Fault Length ◽  
Strong Ground

abstract The problem we address is how to predict strong ground motions for very large earthquakes from observations made of such motions produced by events of moderate size. The discussion is in terms of two basic rupture models, a W model in which slip is controlled by fault width and an L model in which slip is controlled by fault length. Because mean slip is observed to increase linearly with fault length, a long earthquake cannot be modeled as a series of shorter events placed end to end. Rather, to explain the correlation of slip with length, a W model will predict that stress drop increases with length, whereas an L model will predict that stress drop is constant but rise time (slipping duration) increases with length. Thus, a W model predicts that peak and rms accelerations and peak and asymptotic particle velocities increase linearly with fault length. An L model predicts that rms acceleration and asymptotic velocities are independent of length but that the peak velocities increase with the square root of length and peak acceleration with InL.

Use of empirical Green's functions, spectral ratios, and kinematic source models for simulating strong ground motion

1996 ◽  
Vol 86 (3) ◽  
pp. 597-615 ◽  
Author(s):  
R. A. W. Haddon
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Ground Motions ◽  
Spectral Characteristics ◽  
Spectral Ratios ◽  
Spectral Models ◽  
Lg Wave ◽  
Wave Trains ◽  
Large Earthquakes ◽  
Strong Ground

Abstract Ground motions for large and moderately large earthquakes at short and moderate distances are particularly important for seismic hazard estimation in eastern North America (ENA). Very few direct observations of such ground motions have been obtained, however, because of the sparsity of recording sites and the relatively low rates of occurrence of large earthquakes inside the region. Estimation of strong ground motion must therefore rely heavily on theoretical models to extend empirical results obtained from small earthquakes and from the few larger ones for which reliable data are available. Because of the generally large distances between recording stations, the main source of useful data comes from Lg wave trains observed at relatively large distances. For the two largest earthquakes to have occurred near populated regions of southeastern Canada during the past decade, spectral ratios of the Lg wave trains of the mainshocks, with respect to those of their aftershocks, are found to depend almost entirely upon the source radiation characteristics of the sources alone. This result is utilized to derive elastodynamically-based kinematic rupture models that are consistent with the empirical spectral ratio data. Such models provide a firm physical basis from which to infer the most probable spectral characteristics for future large earthquakes in the region. In converse application, it is shown that spectral ratios obtained from such models, along with empirical seismograms from small earthquakes, can be used to accurately simulate strong ground motions at short and moderate (as well as large) distances. As such small-event seismograms are relatively plentiful, the problem of reliable strong ground motion estimation is therefore reduced to that of obtaining reliable representative source spectral models. The solution of this latter problem must continue to depend upon whatever empirical data are available and upon appropriately detailed theoretical modeling.

scholarly journals Simulation of strong ground motions

1980 ◽  
Vol 70 (2) ◽  
pp. 617-630
Author(s):  
David M. Hadley ◽  
Donald V. Helmberger
Keyword(s):  
Ground Motions ◽  
Strike Slip ◽  
Peak Acceleration ◽  
Limited Data ◽  
Distance Curve ◽  
Data Set ◽  
Strong Ground Motions ◽  
Parkfield Earthquake ◽  
Large Earthquakes ◽  
Strong Ground

abstract The estimation of potential strong ground motions at short epicentral distances (Δ = 10 to 25 km) resulting from large earthquakes, M ≧ 6.5, generally requires extrapolation of a limited data set. The goal of this project has been to quantify the extrapolation through a simulation technique that relies heavily upon the more extensive data set from smaller magnitude earthquakes. The simulation utilizes the smaller events as Green's functions for the elements of a larger fault. Comparison of the simulated peak acceleration and duration with the data from the Parkfield earthquake is very good. Simulation of three earthquakes, M = 5.5, 6.5, and 7.0 indicate that the slope of the peak acceleration versus distance curve (Δ = 5 to 25 km) flattens, for strike-slip earthquakes, as the magnitude increases.

scholarly journals Inelastic displacement ratios for non-structural components in steel framed structures under forward-directivity near-fault strong-ground motion

2021 ◽  
Author(s):  
M. A. Bravo-Haro ◽  
J. R. Virreira ◽  
A. Y. Elghazouli
Keyword(s):  
Strong Ground Motion ◽  
Ground Motions ◽  
Structural Elements ◽  
Structural Components ◽  
Framed Structures ◽  
Inelastic Displacement ◽  
Near Fault ◽  
Forward Directivity ◽  
The Mean ◽  
Strong Ground

AbstractThis paper describes a detailed numerical investigation into the inelastic displacement ratios of non-structural components mounted within multi-storey steel framed buildings and subjected to ground motions with forward-directivity features which are typical of near-fault events. The study is carried out using detailed multi-degree-of-freedom models of 54 primary steel buildings with different structural characteristics. In conjunction with this, 80 secondary non-structural elements are modelled as single-degree-of-freedom systems and placed at every floor within the primary framed structures, then subsequently analysed through extensive dynamic analysis. The influence of ground motions with forward-directivity effects on the mean response of the inelastic displacement ratios of non-structural components are compared to the results obtained from a reference set of strong-ground motion records representing far-field events. It is shown that the mean demand under near-fault records can be over twice as large as that due to far-fault counterparts, particularly for non-structural components with periods of vibration lower than the fundamental period of the primary building. Based on the results, a prediction model for estimating the inelastic displacement ratios of non-structural components is calibrated for far-field records and near-fault records with directivity features. The model is valid for a wide range of secondary non-structural periods and primary building fundamental periods, as well as for various levels of inelasticity induced within the secondary non-structural elements.

High-Frequency Spectral Decay Characteristics of Seismic Records of Inland Crustal Earthquakes in Japan: Evaluation of the fmax and κ Models

2020 ◽  
Vol 110 (2) ◽  
pp. 452-470
Author(s):  
Masato Tsurugi ◽  
Reiji Tanaka ◽  
Takao Kagawa ◽  
Kojiro Irikura
Keyword(s):  
Ground Motion ◽  
High Frequency ◽  
Strong Ground Motion ◽  
Cutoff Frequency ◽  
Source Model ◽  
Power Coefficient ◽  
Crustal Earthquakes ◽  
Log Linear ◽  
Large Earthquakes ◽  
Strong Ground

ABSTRACT We examined high-frequency spectral decay characteristics of ground motions for inland crustal earthquakes in Japan, which are important in strong ground motion predictions. We examined 105 earthquakes (Mw 3.3–7.1), including seven large earthquakes (Mw 5.9–7.1). Spectral decay characteristics were accurately evaluated assuming the ω-squared source model and using two approaches: the fmax model (commonly used in Japan), described by the cutoff frequency fmax and the power coefficient of spectral decay s, and the κ model (commonly used in worldwide), the exponential spectral decay model, described by the parameter κ and the specific frequency fE at which a spectrum starts to decrease linearly with increasing frequency in log–linear space. For large earthquakes, we estimated fmax to range from 6.5 to 9.9 Hz and s from 0.78 to 1.60 in the fmax model, and κ to range from 0.014 to 0.051 s and fE from 2 to 4.5 Hz in the κ model. In both approaches, we found that the spectral decay characteristics are regionally dependent. fmax in the fmax model and fE in the κ model tended to be smaller for large earthquakes than for moderate and small earthquakes, clearly demonstrating a seismic moment dependency. We confirmed positive correlations between equivalent parameters of the two approaches, that is, between s and κ and between fmax and fE. Moreover, we found that both approaches are appropriate for evaluating spectral decay characteristics, as long as the spectral decay parameters are appropriately evaluated by comparison with observed spectra. We examined the effects of the spectral decay characteristics on strong ground motion predictions, and demonstrated that simulated motions corrected using the fmax model and those corrected using the κ model are almost the same. The results presented in this article contribute to improving predictions of high-frequency strong ground motion.

scholarly journals Properties of strong ground motion earthquakes*

1955 ◽  
Vol 45 (3) ◽  
pp. 197-218
Author(s):  
George W. Housner
Keyword(s):  
Strong Ground Motion ◽  
Wave Train ◽  
Square Root ◽  
Earthquake Fault ◽  
Relative Slip ◽  
Logarithmic Measure ◽  
Upper Limits ◽  
Slip Area ◽  
Sudden Release ◽  
Strong Ground

Summary The analysis given here considers that an earthquake fault is formed by the superposition of a large number of incremental shear dislocations the sudden release of which produces the earthquake. It is postulated that during an earthquake the incremental dislocations are released in such a way that the average slip is proportional to the square root of the area of slip, and that the probability of release of individual incremental dislocations is such that the probability of a total slip area A is inversely proportional to A. With these two postulates a frequency distribution of earthquakes is derived that agrees with observed data; the Richter magnitude is shown to be essentially a logarithmic measure of the average slip on a fault; and an expression is derived for the energy released by an earthquake that agrees with that derived from consideration of the energy carried in a wave train. Expressions are derived also for the areas of slip during earthquakes, the maximum relative slip, and the average annual, over-all shearing distortion of the state of California and these are in satisfactory agreement with observed behavior. It is assumed that an accelerogram is formed by the superposition of a large number of elemental acceleration pulses random in time. It is shown that this agrees with recorded accelerograms, and an accelerogram composed in this fashion is shown to have the characteristics of actual recorded accelerograms. It is also shown that the maximum ground accelerations in the vicinity of the center of the fault, so far as they are dependent upon the size of the slip area, have essentially reached their upper limits for shocks with areas of slip approximately equal to that associated with the El Centro earthquake of 1940.

The Simulation of Strong Ground Motion Using Empirical Green Function and Stochastic Method for Southern Taiwan Area

2018 ◽  
Author(s):  
Tsung-Jen Teng ◽  
Pei-Ting Chen ◽  
Ting-Wei Chang ◽  
Yuan-Sen Yang ◽  
Chien-Kuo Chiu ◽  
...  
Keyword(s):  
Green Function ◽  
Ground Motion ◽  
Strong Ground Motion ◽  
Ground Motions ◽  
Large Earthquake ◽  
Green Function Method ◽  
Strong Ground Motions ◽  
Empirical Green Function ◽  
Southern Taiwan ◽  
Strong Ground

This study presents strong ground motion simulation methods for the future fragility study of a power plant in Southern Taiwan. The modified stochastic method and empirical Green function method are utilized to synthesize the strong ground motions of specific events. A modified physical random function model of strong ground motions for specific sites and events is presented in this study with verification of sample level. Based on the special models of the source, path, and local site, the random variables of the physical random function of strong ground motions is obtained. The inverse Fourier transform is used to simulate strong ground motions. For the empirical Green function method, the observed site records from small earthquake events occurring around the source area of a large earthquake are collected to simulate the broadband strong ground motion from a large earthquake event. Finally, an application of proposed two simulated methods of this study for simulating the ground motion records of Nishi-Akashi Station at 1995 Kobe earthquake and 2006 Southern Taiwan PingDong earthquake are presented.

New attenuation relations for peak and expected accelerations of strong ground motion

1982 ◽  
Vol 72 (6A) ◽  
pp. 2307-2322
Author(s):  
Bruce A. Bolt ◽  
N. A. Abrahamson
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Regression Line ◽  
General Distribution ◽  
Least Squares Regression ◽  
Peak Acceleration ◽  
Attenuation Relations ◽  
Additional Increase ◽  
Data Set ◽  
Strong Ground

abstract Two proposals are presented on the estimation of maximum accelerations of strong ground motion near the causative fault. First, the crucial selection of the form fitted to observed accelerations as a function of distance from the source is discussed. In particular, evidence is given that the attenuation form adopted by Joyner et al. (1981) constrains the attenuation parameters so that inferences on near-fault motion and magnitude dependence are questionable. An alternative attenuation form is proposed which decouples far-field variations from near-field variations. Nonlinear least-squares regression to the same data set confirms the flattening of attenuation curves near to the source (<10 km) in the magnitude range 5.0 < M < 7.0 and shows no indication (from the small amount of data available) of any additional increase in acceleration for M > 7 earthquakes. For 6.0 ≦ M ≦ 7.7, the regression yields y = 1.6 { ( x + 8.5 ) 2 + 1 } − 0.19 exp { − 0.026 ( x + 8.5 ) } where y is the peak horizontal acceleration in g, and x (km) is the closest distance to the surface projection of the rupture. Second, a robust and easily computed parameter is defined for significant peak acceleration that meets many engineering requirements. This “effective” peak acceleration is obtained by developing histograms for the number of peaks and troughs on the observed record and by choosing the acceleration value at about the 90 percentile level. This truncation excludes scattered outliers of high-amplitude peaks not representative of the general distribution of the ground motion amplitudes. Corresponding values for “effective peak acceleration” are tabulated for part of the basic data set, and it is demonstrated that the scatter about the attenuation regression line is reduced using the proposed parameter.

Turkey-Adjusted NGA-W1 Horizontal Ground Motion Prediction Models

2016 ◽  
Vol 32 (1) ◽  
pp. 75-100 ◽  
Author(s):  
Zeynep Gülerce ◽  
Bahadır Kargoığlu ◽  
Norman A. Abrahamson
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Prediction Models ◽  
Ground Motions ◽  
Site Amplification ◽  
Motion Prediction ◽  
Ground Motion Prediction ◽  
Data Set ◽  
Horizontal Ground Motion ◽  
Strong Ground

The objective of this paper is to evaluate the differences between the Next Generation Attenuation: West-1 (NGA-W1) ground motion prediction models (GMPEs) and the Turkish strong ground motion data set and to modify the required pieces of the NGA-W1 models for applicability in Turkey. A comparison data set is compiled by including strong motions from earthquakes that occurred in Turkey and earthquake metadata of ground motions consistent with the NGA-W1 database. Random-effects regression is employed and plots of the residuals are used to evaluate the differences in magnitude, distance, and site amplification scaling. Incompatibilities between the NGA-W1 GMPEs and Turkish data set in small-to-moderate magnitude, large distance, and site effects scaling are encountered. The NGA-W1 GMPEs are modified for the misfit between the actual ground motions and the model predictions using adjustments functions. Turkey-adjusted NGA-W1 models are compatible with the regional strong ground motion characteristics and preserve the well-constrained features of the global models.

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