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We develop a generic ground-motion prediction equation (GMPE) that can be adjusted for use in any region by modifying a few key model parameters. The basis of the GMPE is an equivalent point-source simulation model whose parameters have been calibrated to empirical data in California, in such a way as to determine the decoupled effects of basic source and attenuation parameters on ground-motion amplitudes. We formulate the generic GMPE as a function of magnitude, distance, stress parameter, geometrical spreading rate, and anelastic attenuation. This provides a fully adjustable predictive model, allowing users to calibrate its parameters using observed motions in the target region. We also include an empirical calibration factor to account for residual effects that are different from and/or missing in simulations compared to observed motions in the target region. As an example, we show how the generic GMPE can be adjusted for use in central and eastern North America (CENA), and calibrated with the Next Generation Attenuation-East database. We provide median predictions of ground motions in CENA for average horizontal-component peak ground motions and 5% damped pseudospectral acceleration (periods up to T 10 s), for magnitudes M 3-8 and distances up to 600 km.

Response spectra for California earthquakes of 3:0 ≤ M < 7:5 are well described by a simple stochastic ground-motion model using an equivalent point-source concept. We determine the best-fit stress parameter of each California earthquake in the Next Generation Attenuation-West 2 database based on matching simulated to observed response spectral shapes over a wide frequency range, and we derive an expression for the mean stress as a function of magnitude and focal depth. A calibration factor is calculated for each event; this constant is the required amplitude adjustment in order that the simulations match the observed response spectral amplitudes with zero bias. The best-fit simulation model suggests that the attenuation in California can be modeled as R −1:3 at distances < 50 km and R −0:5 at further distances; this does a better job at matching attenuation trends than the traditional model 1=R model at distances < 50 km, particularly for M < 5:5 events. The model requires an overall multiplicative calibration factor of C sim 3:16 in order for the simulations to match the observed response spectral amplitudes, for all magnitudes and distances. The calibration constant could be attributed to simplifications inherent in the modeling of source, attenuation, and site processes, and the lack of consideration of multiple phases in stochastic simulations. We conclude that the equivalent point-source simulation method with the proposed modeling parameters can predict average ground motions in California, generally within a 25% error band, for magnitudes up to M 7.5, distances < 400 km, and frequencies > 0:2 Hz. We finish the paper by providing a recipe for developing a simulation-based generic ground-motion prediction equation that can be adjusted for source and attenuation attributes in different regions by simple modifications to its key source and attenuation modeling parameters.

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We develop a simple model to estimate moment magnitude for events of M < 4 at distances out to ∼300 km, based on readily available ShakeMap parameters and seismological scaling principles. Estimates of moment magnitude for such small events are not available from standard methods but are needed for local-network applications and for traffic light systems for induced-seismicity applications. This issue is currently of particular interest in central and eastern North America. The method takes advantage of the fact that for small events the response spectrum is well-correlated with seismic moment for periods greater than 0.3 s and can be predicted from a simple stochastic point-source model. We develop an equation by which we calculate M from the 1 s pseudoacceleration amplitudes (PSA) (M ≥ 3) or the 0.3 s PSA (M < 3) at each station, using a simple linear equation that corrects for the effects of attenuation. We show that this method produces unbiased estimates of moment magnitudes in both eastern and western North America, for M ≤ 4 events recorded at distances < 300 km.

The range of response frequencies for which spectral ordinates obtained from accelerograms may be considered reliable is limited by several factors, primary among them being the effects of filters that are routinely applied to remove noise from the records. Considerable attention has been focused on the low-frequency limit of the usable spectral ordinates because of various engineering applications requiring long-period spectral accelerations or displacements but only recently have rational approaches to selecting the high-frequency limit been proposed. Since there are applications for which the high-frequency spectral ordinates are important, the approaches to this issue presented in the recent studies are reviewed and their application to the ground-motion database from Europe and the Middle East is explored. On the basis of the results of these analyses, it is concluded that a large proportion of this dataset can be used to provide reliable estimates of response spectral ordinates at much shorter periods than may have previously been considered feasible. S. AKKAR ET AL.ordinates are of particular importance. The importance of high-frequency response is also increased when the vertical component of motion is of consideration, especially if the vertical spectrum is to be obtained through the use of vertical-to-horizontal spectral ratios to scale the horizontal response spectrum.Another application for which high-frequency ordinates can be important, albeit indirectly, is the inversion of empirical ground-motion predictions to find equivalent stochastic parameters [3], which can then be used to apply host-to-target conversions to transport models from one region to another [4]. The stability of such inversions is improved if the response spectrum is defined in detail across a wide range of response frequencies, and in particular at high frequencies.Ground-motion prediction equations (GMPEs) for response spectral accelerations have generally provided coefficients for the prediction of peak ground acceleration (PGA) and the spectral acceleration at a large number of response periods. The shortest period for which coefficients are presented has varied significantly among published models [5], but the reasons behind the selection of the minimum period (other than 0.0 s, corresponding to PGA) is often not explicitly stated. In some cases the shortest period may have been chosen purely on the basis of the smallest value deemed to be of relevance to structural engineering. In other cases, the minimum period may have been inferred from the nature of the instruments that produced the record, since analogue accelerographs are generally incapable of capturing motions at frequencies equal to or greater than that of the transducer. For the SMA-1 accelerograph, for example, the instrument response distorts ground motion with frequencies of greater than about 20 Hz [6]. Although procedures have been developed to apply corrections for the effect of the transducer frequency, it has been noted that their application will amplify b...

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The accurate modeling of ground motion for induced-seismicity hazard estimation is critically dependent on how amplitudes scale with distance near the hypocenter. A rich database of ground motions from small events recorded at close distances in the Geysers region of California has been used to constrain the near-distance saturation effects that control the maximum observed ground motions and intensities for shallow-induced events. The results of this study support the modeling of these effects using an equivalent point-source concept, in which the effective source depth increases from a value near 1 km at moment magnitude (M) of 2 to a value near 3 km at M 4. This near-distance saturation behavior can be applied to the development of ground-motion models for induced seismicity in any region. BSSA Early Edition / 1