Location

St. Louis, Missouri

Session Start Date

3-11-1991

Session End Date

3-15-1991

Abstract

Local soil conditions can yield to significant variations in ground motion generated by earthquakes. During the last two decades, these amplification effects have been observed by numerous authors for well-documented earthquakes. On the other hand, theoretical models and numerical techniques have been proposed to physically understand site effects. However, few comparisons have been made between observations and theoretical results for well-known 2D structures (sediment-filled valleys). The aim of this paper is to present a study of the response of a valley in the French Alps. The structure (Ubaye valley) was chosen for its moderate dimensions (500 meters wide and 65 meters thick) which allow an accurate determination of the deposit characteristics, and for the relatively high seismicity of the region. The study has included the set-up of a temporary array of five seismological stations, a geophysical survey of the valley to determine the dynamic properties and the geometry of the soft deposits, and numerical modeling (1D and 2D cases) of the response. Comparisons between observed and computed amplifications show a good agreement for particular input motions (corresponding to the SH case). In the other cases, the spectral ratios exhibit a great variability between different groups of similar earthquakes and more developed simulations should be used (2D P-SV, 3D).

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Second Conference

Publisher

University of Missouri--Rolla

Publication Date

3-11-1991

Document Version

Final Version

Rights

© 1991 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Mar 11th, 12:00 AM Mar 15th, 12:00 AM

Site Amplification Effects in the Ubaye Valley (France): Measurements and Modeling

St. Louis, Missouri

Local soil conditions can yield to significant variations in ground motion generated by earthquakes. During the last two decades, these amplification effects have been observed by numerous authors for well-documented earthquakes. On the other hand, theoretical models and numerical techniques have been proposed to physically understand site effects. However, few comparisons have been made between observations and theoretical results for well-known 2D structures (sediment-filled valleys). The aim of this paper is to present a study of the response of a valley in the French Alps. The structure (Ubaye valley) was chosen for its moderate dimensions (500 meters wide and 65 meters thick) which allow an accurate determination of the deposit characteristics, and for the relatively high seismicity of the region. The study has included the set-up of a temporary array of five seismological stations, a geophysical survey of the valley to determine the dynamic properties and the geometry of the soft deposits, and numerical modeling (1D and 2D cases) of the response. Comparisons between observed and computed amplifications show a good agreement for particular input motions (corresponding to the SH case). In the other cases, the spectral ratios exhibit a great variability between different groups of similar earthquakes and more developed simulations should be used (2D P-SV, 3D).