Topographic effect on ground motion for incident P-waves

Rogers, A.M.; Katz, Lewis J.; Bennett, Theron J.

doi:10.1016/0148-9062(74)91617-9

Cited by 5 publications

(8 citation statements)

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“…Second, from a quantitative viewpoint, however, clear discrepancies exist between theory and observations. Cases have been reported in which field measurements exhibit only very weak amplifications at ridge crests and fit very well the numerical results (Rogers et al, 1974). However, numerous cases also exist in which the observed amplifications are significantly larger than the theoretical predictions obtained from sophisticated, two-or three-dimensional models (Bouchon et al, 1995).…”

Section: Theoretical and Numerical Studiesmentioning

confidence: 80%

“…The strengthening of the forward-scattered Rayleigh wave in the P case has also been experimentally verified by Rogers et al (1974). Published site-specific analyses show, however, that even if topographic amplification phenomena are more pronounced for obliquely incident waves, the absolute magnitude of acceleration at the crest (both horizontal and vertical) is, in general, larger for vertically propagating waves.…”

Section: Theoretical and Numerical Studiesmentioning

confidence: 95%

“…Nonetheless, observed amplification levels both in the time and frequency domain were much larger than the values predicted by theoretical models; even greater discrepancies were reported for spectral amplification values. Rogers et al (1974) recorded an underground nuclear explosion at several sites across the NASA Mountain in Nevada. They performed only time-domain comparisons of crest and base motions, and the observed amplifications are about 25%, which is in good agreement with theoretical predictions.…”

Section: Theoretical and Numerical Studiesmentioning

confidence: 99%

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Effects of Local Soil Conditions on the Topographic Aggravation of Seismic Motion: Parametric Investigation and Recorded Field Evidence from the 1999 Athens Earthquake

Assimaki¹

2005

Bulletin of the Seismological Society of America

156

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During the 1999 Athens earthquake, the town of Adàmes, located on the eastern side of the Kifissos river canyon, experienced unexpectedly heavy damage. Despite the particular geometry of the slope that caused significant motion amplification, topography effects alone cannot explain the uneven damage distribution within a 300-m zone parallel to the canyon's crest, which is characterized by a rather uniform structural quality. In this article, we illustrate the important role of soil stratigraphy and material heterogeneity on the topographic aggravation of surface ground motion. For this purpose, we first conduct an extensive time-domain parametric study using idealized stratified profiles and Gaussian stochastic fields to characterize the spatial distribution of soil properties, and using Ricker wavelets to describe the seismic input motion; the results show that both topography and local soil conditions significantly affect the spatial variability of seismic motion. We next perform elastic two-dimensional wave propagation analyses based on available local geotechnical and seismological data and validate our results by comparison with aftershock recordings.

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Section: Theoretical and Numerical Studiesmentioning

confidence: 80%

Section: Theoretical and Numerical Studiesmentioning

confidence: 95%

Section: Theoretical and Numerical Studiesmentioning

confidence: 99%

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Effects of Local Soil Conditions on the Topographic Aggravation of Seismic Motion: Parametric Investigation and Recorded Field Evidence from the 1999 Athens Earthquake

Assimaki¹

2005

Bulletin of the Seismological Society of America

156

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“…(iv) However, from a quantitative viewpoint, the situation is somewhat confusing, as already stated in Geli et al [1988]. There exist cases where field measurements exhibit only very weak amplifications at ridge crests, and fit very well the numerical results [Rogers et al, 1974]. However, there also exist numerous cases where the observed amplifications are significantly larger than the theoretical predictions obtained from sophisticated, two-or three-dimensional models [Bouchon et al, 1995].…”

Section: Conclusion Of the Reviewmentioning

confidence: 81%

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Assimaki¹

2004

J. Earth. Eng.

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A time-domain parametric study for the seismic response of a region located on the eastern bank of the Kifisos river canyon is performed to evaluate the significance of topography and soil effects on the seismic response of slopes. This region experienced unexpectedly heavy damage during the 7 September 1999 Ms 5.9 earthquake. Twodimensional finite-element and spectral-element analyses are conducted using Ricker wavelets of various central frequencies as horizontal and vertical base excitation. The significance of a layered soil profile and the frequency content of the input motion, the emergence of "parasitic" acceleration components, and the effect of the angle of incidence on the amplification of the incoming waves are all discussed in detail. It is shown that the presence of a surface soil layer significantly affects the amplification pattern. The so-called Topographic Aggravation Factor (defined as the 2D/1D Fourier spectral ratio) achieves its maximum value very near the crest, in function of the frequency content of the excitation. For the particular soil conditions and geometry analysed, vertically propagating SV waves incite at about the critical angle, resulting in the highest topographic amplification.

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“…Boundary conditions imposed on the bounded surface layer are uz=o=0au=0 (7) az z=i uxo=uxL=0 (8) Expressing the displacement in geometric coordinates as u(xzt)=U(x)W(z)exp(icit) (9) and substituting this into Eq. (6) lead to (10) where denotes vibration circular frequency.…”

Section: Discussionmentioning

confidence: 99%