Sediment-induced amplification and the collapse of the Nimitz Freeway

Nature
By: , and 

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Abstract

The amplification of ground motion by low-seismic-velocity surface sediments is an important factor in determining the seismic hazard specific to a given site. The Ms = 7.1 Loma Prieta earthquake of 17 October 1989 was the largest event in the contiguous United States in 37 years, and yielded an unparalleled volume of seismic data from the main shock and aftershock sequence1. These data can be used to image the seismic source, to study detailed Earth structure, and to study the propagation of seismic waves both through bedrock at depth and through sediment layers near the surface. Near the edge of San Francisco Bay, site conditions vary considerably on scales of hundreds of metres. The collapsed section of the two-tiered Nimitz Freeway in Oakland was built on San Francisco Bay mud, whereas stiffen alluvial sediments underlie a southern section that was damaged but did not collapse. Here we analyse high-quality, digital aftershock recordings from several sites near the Nimitz Freeway, and conclude that soil conditions and resulting ground-motion amplification may have contributed significantly to the failure of the structure.

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Publication type Article
Publication Subtype Journal Article
Title Sediment-induced amplification and the collapse of the Nimitz Freeway
Series title Nature
DOI 10.1038/344853a0
Volume 344
Issue 6269
Year Published 1990
Language English
Publisher Springer
Description 3 p.
First page 853
Last page 855
Country United States
State California
City Oakland
Other Geospatial Nimitz Freeway
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