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Title: An experimental topographic amplification study at Los Alamos National Laboratory using ambient vibrations

Abstract

An experimental study aimed at investigating potential topographic amplification of seismic waves was conducted on a 50-m-tall and 185-m-wide soft-rock ridge located at Los Alamos National Laboratory near Los Alamos, New Mexico. Ten portable broadband seismograph stations were placed in arrays across the ridge and left to record ambient vibration data for ~9 hours. Clear evidence of topographic amplification was observed by comparing spectral ratios calculated from ambient noise recordings at the toe, slope, and crest of the instrumented ridge. The inferred resonance frequency of the ridge obtained from the experimental recordings was found to agree well with several simple estimates of the theoretical resonance frequency based on its geometry and stiffness. Results support the feasibility of quantifying the frequency range of topographic amplification solely using ambient vibrations, rather than strong or weak ground motions. Additionally, comparisons have been made between a number of widely used experimental methods for quantifying topographic effects, such as the standard spectral ratio, median reference method, and horizontal-to-vertical spectral ratio. As a result, differences in the amplification and frequency range of topographic effects indicated by these methods highlight the importance of choosing a reference condition that is appropriate for the site-specific conditions and goals associatedmore » with an experimental topographic amplification study.« less

Authors:
 [1];  [1];  [2]
  1. Univ. of Texas, Austin, TX (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Programs (DP) (NA-10)
OSTI Identifier:
1358161
Report Number(s):
LA-UR-16-26142
Journal ID: ISSN 0037-1106
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Bulletin of the Seismological Society of America
Additional Journal Information:
Journal Volume: 107; Journal Issue: 3; Journal ID: ISSN 0037-1106
Publisher:
Seismological Society of America
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Earth Sciences; site response, topographic site correction

Citation Formats

Stolte, Andrew C., Cox, Brady R., and Lee, Richard C. An experimental topographic amplification study at Los Alamos National Laboratory using ambient vibrations. United States: N. p., 2017. Web. doi:10.1785/0120160269.
Stolte, Andrew C., Cox, Brady R., & Lee, Richard C. An experimental topographic amplification study at Los Alamos National Laboratory using ambient vibrations. United States. doi:10.1785/0120160269.
Stolte, Andrew C., Cox, Brady R., and Lee, Richard C. Tue . "An experimental topographic amplification study at Los Alamos National Laboratory using ambient vibrations". United States. doi:10.1785/0120160269. https://www.osti.gov/servlets/purl/1358161.
@article{osti_1358161,
title = {An experimental topographic amplification study at Los Alamos National Laboratory using ambient vibrations},
author = {Stolte, Andrew C. and Cox, Brady R. and Lee, Richard C.},
abstractNote = {An experimental study aimed at investigating potential topographic amplification of seismic waves was conducted on a 50-m-tall and 185-m-wide soft-rock ridge located at Los Alamos National Laboratory near Los Alamos, New Mexico. Ten portable broadband seismograph stations were placed in arrays across the ridge and left to record ambient vibration data for ~9 hours. Clear evidence of topographic amplification was observed by comparing spectral ratios calculated from ambient noise recordings at the toe, slope, and crest of the instrumented ridge. The inferred resonance frequency of the ridge obtained from the experimental recordings was found to agree well with several simple estimates of the theoretical resonance frequency based on its geometry and stiffness. Results support the feasibility of quantifying the frequency range of topographic amplification solely using ambient vibrations, rather than strong or weak ground motions. Additionally, comparisons have been made between a number of widely used experimental methods for quantifying topographic effects, such as the standard spectral ratio, median reference method, and horizontal-to-vertical spectral ratio. As a result, differences in the amplification and frequency range of topographic effects indicated by these methods highlight the importance of choosing a reference condition that is appropriate for the site-specific conditions and goals associated with an experimental topographic amplification study.},
doi = {10.1785/0120160269},
journal = {Bulletin of the Seismological Society of America},
number = 3,
volume = 107,
place = {United States},
year = {Tue Mar 14 00:00:00 EDT 2017},
month = {Tue Mar 14 00:00:00 EDT 2017}
}

Journal Article:
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