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Title: Spectral characteristics of small magnitude earthquakes with application to western and eastern North American tectonic environments : surface motions and depth effects
Authors: Woodward-Clyde Consultants.
Darragh, Robert B. (Robert Bernard)
Green, Robert K.
Turcotte, F. Thomas.
Keywords: Earthquakes
Ground motions
Response spectra
North America
Earthquake engineering
Publisher: Geotechnical Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; GL-89-16.
Description: Miscellaneous Paper
Abstract: The band-limited-white-noise model employed in the WES-RASCAL computer program has been used to predict response spectral shapes for small magnitude earthquakes (moment magnitude (M𝚠) ≈ 5.3 to 2.5) in both eastern and western North America. Model predictions are compared to spectral shapes computed from data recorded in both eastern North America (ENA) and western North America (WNA) tectonic provinces. The ground motion model produces reliable and accurate predictions of spectral composition as well as peak accelerations for these small magnitude earthquakes. Results of magnitude and distance scaling of response spectral shapes show little distance dependence in the range of 5 to 25 km, but a strong magnitude dependence in the range M𝚠 2.5 to 5.3. Representative synthetic acceleration time histories have also been generated at close ranges for rock outcrops with properties typical of WNA and ENA. The synthetic motions compare favorably in peak acceleration, duration, and spectral content with recorded data at comparable magnitudes and ranges. Ground motions are also examined at depths of 50, 100, and 150 m within a halfspace. The effects of depth upon response spectra, Fourier spectra, peak acceleration, and peak particle velocity are shown. Depth-dependent spectral nodes are present in the Fourier and response spectra. Both peak acceleration and peak particle velocity decrease with depth. Peak acceleration decreases more rapidly with depth than does peak particle velocity.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Miscellaneous Paper

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