Modeling Geometrical Spreading and the Relative Amplitudes of Vertical and Horizontal High-Frequency Ground Motions in Eastern North America

2012 ◽  
Vol 102 (5) ◽  
pp. 1957-1975 ◽  
Author(s):  
M. C. Chapman ◽  
R. W. Godbee
Keyword(s):  
North America ◽  
High Frequency ◽  
Ground Motions ◽  
Eastern North America ◽  
Geometrical Spreading

Evaluation of models for earthquake source spectra in eastern North America

1998 ◽  
Vol 88 (4) ◽  
pp. 917-934
Author(s):  
Gail M. Atkinson ◽  
David M. Boore
Keyword(s):  
North America ◽  
Ground Motion ◽  
High Frequency ◽  
Ground Motions ◽  
Source Model ◽  
Eastern North America ◽  
Long Period ◽  
Source Models ◽  
Felt Area ◽  
Large Earthquakes

Abstract There have been several relations proposed in the last few years to describe the amplitudes of ground motion in eastern North America (ENA). These relations differ significantly in their assumptions concerning the amplitude and shape of the spectrum of energy radiated from the earthquake source. In this article, we compare ground motions predicted for these source models against the sparse ENA ground-motion database. The source models evaluated include the two-corner models of Boatwright and Choy (1992), Atkinson (1993a), Haddon (1996), and Joyner (1997a,b), and the one-corner model of Brune [as independently implemented by Frankel et al. (1996) and by Toro et al. (1997)]. The database includes data from ENA mainshocks of M > 4 and historical ENA earthquakes of M > 5.5, for a total of 110 records from 11 events of 4 ≦ M ≦ 7.3, all recorded on rock. We also include 24 available rock records from 4 large earthquakes in other intraplate regions; conclusions are checked to determine whether they are sensitive to the addition of these non-ENA data. The Atkinson source model, as implemented in the ground-motion relations of Atkinson and Boore (1995), is the only model that provides unbiased ground-motion predictions over the entire period band of interest, from 0.1 to 10 sec. The source models of Frankel et al. (1996), Toro et al. (1997), and Joyner (1997a,b) all provide unbiased ground-motion estimates in the period range from 0.1 to 0.5 sec but overestimate motions at periods of 1 to 10 sec. The Haddon (1996) source model overpredicts motions at all periods, by factors of 2 to 10. These conclusions do not change significantly if data from non-ENA intraplate regions are excluded, although the tendency of all models toward overprediction of long-period amplitudes becomes more pronounced. The tendency of most proposed ENA source models to overestimate long-period motions is further confirmed by an evaluation of the relationship between Ms, a measure of the spectrum at 20-sec period, and moment magnitude. A worldwide catalog of shallow continental earthquakes (Triep and Sykes, 1996) is compared to the Ms-M relations implied by each of the source models. The Atkinson source model is consistent with these data, while other proposed ENA models overpredict the average Ms for a given M. The implications of MMI data from historical earthquakes are also addressed, by exploiting the correlation between felt area and high-frequency source spectral level. High-frequency spectral amplitudes, as specified by the Atkinson and Boore (1995), Frankel et al. (1996), Toro et al. (1997), and Joyner (1997a,b) source models, equal or exceed the levels inferred from the felt areas of most of the large ENA events, with the noteable exception of the Saguenay earthquake. By contrast, high-frequency spectral amplitudes specified by the Haddon (1996) source model agree with the felt area of the Saguenay earthquake but overpredict the felt areas of nearly all other large events. In general, models that fit the Saugenay data—be it intensity data, strong-ground-motion data, regional seismographic data, or telescismic data—will not fit the data from the remaining earthquakes. A source model derived from the California database, suitably modified for regional differences in crustal properties, is also evaluated. This model is not significantly different from the Atkinson model for ENA. There is an important practical application of this similarity, which we develop as an engineering tool: Empirical ground-motion relations for California may be modified to predict ENA ground motions from future large earthquakes.

A high-frequency magnitude scale

1995 ◽  
Vol 85 (3) ◽  
pp. 825-833
Author(s):  
Gail M. Atkinson ◽  
Thomas C. Hanks
Keyword(s):  
North America ◽  
Ground Motion ◽  
Stress Drop ◽  
High Frequency ◽  
Ground Motions ◽  
Amplitude Spectrum ◽  
Average Stress ◽  
Magnitude Scale ◽  
Eastern North America ◽  
Frequency Magnitude

Abstract A high-frequency magnitude scale (m) is proposed: m=2log⁡a˜hf+3, where ãhf is the high-frequency level of the Fourier amplitude spectrum of acceleration in cm/sec (average or random horizontal component), at a hypocentral or closest fault distance of 10 km. m can be determined from either instrumental data or the felt area of an earthquake. The definition of m has been arranged such that m = M (moment magnitude) for events of “average” stress drop, in both eastern North America (ENA) and California. m provides a measure of the stress drop if M is also known. The observed relationship between m and M indicates that the average stress drop is about 150 bars for ENA earthquakes, and about 70 bars for California earthquakes. The variability of stress drop is much larger in ENA than in California. The chief justification for the m scale is its utility in the interpretation of the large preinstrumental earthquakes that are so important to seismic hazard estimation in eastern North America. For such events, m can be determined more reliably than can M or mN (Nuttli magnitude), and forms a much better basis for estimating high-frequency ground motions. When used as a pair, m and M provide a good index of ground motion over the entire engineering frequency band. If both of these magnitudes can be defined for an earthquake then a ground-motion model, such as the stochastic model, can be used to obtain reliable estimates of response spectra and peak ground motions.

Site effects of the Denis-Perron dam (SM-3): A case study in Eastern North America

2021 ◽  
pp. 875529302110194
Author(s):  
Daniel Verret ◽  
Denis LeBœuf ◽  
Éric Péloquin
Keyword(s):  
North America ◽  
Ground Motion ◽  
Site Effects ◽  
Transfer Functions ◽  
Ground Motions ◽  
Published Data ◽  
Eastern North America ◽  
Ground Acceleration ◽  
Large Dams ◽  
Moderate Seismicity

Eastern North America (ENA) is part of a region with low-to-moderate seismicity; nonetheless, some significant seismic events have occurred in the last few decades. Recent events have reemphasized the need to review ENA seismicity and ground motion models, along with continually reevaluating and updating procedures related to the seismic safety assessment of hydroelectric infrastructures, particularly large dams in Québec. Furthermore, recent researchers have shown that site-specific characteristics, topography, and valley shapes may significantly aggravate the severity of ground motions. To the best of our knowledge, very few instrumental data from actual earthquakes have been published for examining the site effects of hydroelectric dam structures located in eastern Canada. This article presents an analysis of three small earthquakes that occurred in 1999 and 2002 at the Denis-Perron (SM-3) dam. This dam, the highest in Québec, is a rockfill embankment structure with a height of 171 m and a length of 378 m; it is located in a narrow valley. The ground motion datasets of these earthquakes include the bedrock and dam crest three-component accelerometer recordings. Ground motions are analyzed both in the time and frequency domains. The spectral ratios and transfer functions obtained from these small earthquakes provide new insights into the directionality of resonant frequencies, vibration modes, and site effects for the Denis-Perron dam. The crest amplifications observed for this dam are also compared with previously published data for large dams. New statistical relationships are proposed to establish dam crest amplification on the basis of the peak ground acceleration (PGA) at the foundation.

High-Frequency Seismic Wave Propagation in Northeastern North America

1990 ◽  
Vol 61 (3-4) ◽  
pp. 193-208 ◽  
Author(s):  
S. E. Hough ◽  
K. H. Jacob ◽  
L. Seeber
Keyword(s):  
North America ◽  
High Frequency ◽  
Characteristic Length ◽  
Body Waves ◽  
Eastern North America ◽  
Western North America ◽  
Energy Propagation ◽  
Length Scales ◽  
Near Surface ◽  
High Frequencies

Abstract A key element in the assessment of seismic hazard is the estimation of how energy propagation from a given earthquake is affected by crustal structure near the receiver and along the more distant propagation path. In this paper, we present data from a variety of sources in eastern North America recorded at epicentral distances of a few to 800 km, and characterize and interpret systematic features. Site effects have been classically considered in terms of amplification either within a sediment-filled valley or from a single topographic feature (Geli et al., 1988). We present evidence of high frequency (5–30 Hz) resonances observed in hard-rock recordings of both body waves and Lg waves, and suggest that site effect should be expanded regionally to include structural and topographic information over sufficiently large areas to include several wavelengths of any features that may interact with seismic waves in the frequency range of interest. A growing body of evidence suggests that ground motions at high frequencies recorded at large epicentral distances in eastern North America are controlled by resonance effects. We hypothesize that a fundamental difference between eastern and western North America spectra stems from a combination of differences in the character of topography and near-surface structure. Active tectonics of western North America gives rise to a complex crust that scatters seismic energy in a random manner and results in very effective attenuation of high frequencies. The older eastern North American crust contains scatterers that are more ordered, with characteristic length scales that give rise to resonance phenomena in the frequency band critical for earthquake hazard. We present preliminary analysis of topographic data from the Adirondack Mountains in New York that demonstrates the existence of characteristic length scales on the order of up to 1–3 kilometers. Features with these length scales will effectively scatter energy at frequencies in the 1 to 10 Hz range.

Ground Motion Model for Small-to-Moderate Earthquakes in Texas, Oklahoma, and Kansas

2019 ◽  
Vol 35 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Georgios Zalachoris ◽  
Ellen M. Rathje
Keyword(s):  
North America ◽  
Ground Motion ◽  
Induced Seismicity ◽  
Ground Motions ◽  
Site Amplification ◽  
Eastern North America ◽  
Motion Model ◽  
Ground Motion Model ◽  
Magnitude Scaling ◽  
Proposed Model

A ground motion model (GMM) tuned to the characteristics of the observed, and potentially induced, seismicity in Texas, Oklahoma, and Kansas is developed using a database of 4,528 ground motions recorded during 376 events of Mw > 3.0 in the region. The GMM is derived using the referenced empirical approach with an existing Central and Eastern North America model as the reference GMM and is applicable for Mw = 3.0–5.8 and hypocentral distances less than 500 km. The proposed model incorporates weaker magnitude scaling than the reference GMM for periods less than about 1.0 s, resulting in smaller predicted ground motions at larger magnitudes. The proposed model predicts larger response spectral accelerations at short hypocentral distances (≤20 km), which is likely because of the shallow hypocenters of events in Texas, Oklahoma, and Kansas. Finally, the VS30 scaling for the newly developed model predicts less amplification at VS30 < 600 m/s than the reference GMM, which is likely because of the generally thinner sediments in the study area. This finding is consistent with recent studies regarding site amplification in Central and Eastern North America.

Updated GMICE for Central and Eastern North America Extending to Higher Intensities

2020 ◽  
Vol 91 (6) ◽  
pp. 3518-3527
Author(s):  
Chris H. Cramer
Keyword(s):  
North America ◽  
Linear Regression ◽  
Ground Motion ◽  
Ground Motions ◽  
Correlation Equation ◽  
Residual Analysis ◽  
Eastern North America ◽  
Intensity Correlation ◽  
Motion Range

Abstract Recent M 3–5 earthquakes near Cushing, Oklahoma, provide observations of intensity up to eight with accompanying ground motions due to close-in acceleration records at distances less than 30 km from the epicenters. Adding these observations to the existing Central and Eastern North America (CENA) ground-motion intensity correlation equation (GMICE) database allows the updating of a CENA GMICE from a linear (below intensity six) relationship to a more accurate bilinear relationship (up to intensity eight). The updating of the CENA GMICE is accomplished using linear regression and residual analysis. The analysis shows that the bilinear transition is fairly broad in the CENA covering one to two intensity units and one or more orders of magnitude in ground motion, depending on regression direction. The new CENA GMICE reduces the overprediction of ground motions from high intensities and the underprediction of intensities at both ends of the observed ground-motion range.

Shake Table Testing of Slender RC Shear Walls Subjected to Eastern North America Seismic Ground Motions

2012 ◽  
Vol 138 (12) ◽  
pp. 1515-1529 ◽  
Author(s):  
Iman Ghorbanirenani ◽  
Robert Tremblay ◽  
Pierre Léger ◽  
Martin Leclerc
Keyword(s):  
North America ◽  
Ground Motions ◽  
Shear Walls ◽  
Eastern North America ◽  
Shake Table ◽  
Shake Table Testing

Ground motions selection and scaling for nonlinear dynamic analysis of structures located in Eastern North America

2014 ◽  
Vol 41 (3) ◽  
pp. 232-244 ◽  
Author(s):  
Dominic Michaud ◽  
Pierre Léger
Keyword(s):  
North America ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Nonlinear Dynamic Analysis ◽  
Eastern North America ◽  
Seismic Demand ◽  
Nonlinear Behaviour ◽  
Spectral Matching ◽  
Uniform Hazard Spectrum ◽  
Scaling Methods

This paper presents the effectiveness of seven ground motion scaling methods and two spectral matching methods to achieve compatibility with the Canadian National Building Code (CNBC) 2005 uniform hazard spectrum for Montreal to perform nonlinear seismic analysis. Databases of 30 historical records and 30 Eastern North America simulated records have been selected to compute the reference mean seismic demand and its dispersion. The characteristics and destructive capacity of ground motions have been studied using a large number of indices computed from (i) the records themselves, (ii) a series of single degree of freedom structures, as well as (iii) a four-story steel frame. Record scaling methods to the target spectrum using (i) spectral intensity, (ii) reducing the mean square error, (iii) and minimizing dispersion as well as time domain spectral matching generated coherent seismic demand and dispersion in agreement with the reference values. Spectral matching to a specified elastic design spectrum does not reduce the dispersion of the nonlinear response. Therefore close spectral matching cannot be used to reduce the number of records to minimize the resources allocated in seismic safety assessment. At least seven records, as recommended in current CNBC and FEMA (2012) guidelines to compute an average response, should be used to characterize the nonlinear behaviour of structural systems.

scholarly journals Amplification of Earthquake Ground Motions in Washington, DC, and Implications for Hazard Assessments in Central and Eastern North America

2017 ◽  
Vol 44 (24) ◽  
Author(s):  
Thomas L. Pratt ◽  
J. Wright Horton ◽  
Jessica Muñoz ◽  
Susan E. Hough ◽  
Martin C. Chapman ◽  
...  
Keyword(s):  
North America ◽  
Ground Motions ◽  
Eastern North America ◽  
Washington Dc ◽  
Earthquake Ground Motions ◽  
Hazard Assessments
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